About swallow nest, swiftlet, edible bird’s nest

Who gives a spit about bird’s nests?

Toronto Star,  Canada - 16 hours ago
Slinger

It’s called the edible-nest swiftlet because its nests are edible. This is the only reason anybody cares about it.

They are used to make soup.

The swiftlets are an Asian relative of our chimney swifts. Swiftlets, and swifts, are stunningly drab, grey and darker grey. None is as long as the thumb of an average National Basketball Association player. They’re usually seen a long ways up, flittering on narrow, sickle-shaped wings as they hoover in high-flying insects.

Bugs. That’s all they eat.

If they aren’t roosting or nesting, they’re airborne. They feed their fledglings on the wing. More than that, they mate on the wing. Apart from man, they are the only creatures capable of doing it. Unlike man, they do it on their own wings.

The edible-nest swiftlets that swarm from mountain caves 2,800 metres above sea level qualify for automatic membership in the Mile-High Club.

What distinguishes edible-nest swiftlets from their cousins is that the nests they build in the subterranean dark incorporate little by way of twigs or mud. What they’re made of pretty well exclusively is spit.

Their particular spit is goopy and dries to the consistency that elderly readers will be familiar with if they recall the brittle gunk caked around the mouths of paste jars when they were in elementary school.

Certain kids (the kind who were encouraged by their parents to run away and join a circus) enjoyed eating that gunk because, with any luck, some other kid watching this would throw up, so there’s not much about edible-nest swiftlets’ nests that should put off an adventurous eater, which you’re not if the idea of eating swiftlet spit, or that the spit is the end result of a digestive process fuelled by bugs and nothing but, bothers you.

The soup made from these nests is always described as “glutinous.'’ The next most frequent adjective is “tasteless.'’

Yet the demand is such that, according to The Nation, a Bangkok newspaper, the Thai government has collected more than $9.7 million from nest-harvesting companies for concessions in the last four years. The black market is so intense that the swiftlets themselves hover near the edge of extinction.

A Thailand Research Fund report has identified corruption running seamlessly from poachers to government conservation agents to local politicians to, of course, Thailand being Thailand, the police. It’s one of the busiest arenas for money laundering in the country.

When we were there two weeks ago, Thai news organizations were attributing the murder of an administrative official on Koh Mak Island, one of 200 cave-riddled coastal islands where the swiftlets nest, to the trade.

The total number of similar deaths in recent years gets rounded off as “running into the hundreds.'’

For soup. That tastes like flour-and-water paste. Made from bird spit.

Hong Kong is crazy for it, importing $25 million worth of nests a year. A kilogram of the finest kind goes for $2,000.

A bowl of it can set you back $100.

And you probably guessed why. It’s another one of nature’s sure-fire treatments for erectile dysfunction. At least certain men think it is.

They … uh-oh. Hold on a minute. It just occurred to me that the two stories I came back with from my Southeast Asia journeyings (Tuesday it was eating dogs in Vietnam) fall into the same category: masculine stimulants. And it also occurs to me that there might be something weird about this.

If it wasn’t a fluke, I hate to think what else is going on in my subconscious.

Because I, personally, don’t have any problems in that regard. Seriously. None at all. Considering my age.

 

Add comment November 30th, 2007

ENDANGERED SPECIES: BIRD’S NEST SOUP

query.nytimes.com
By NICHOLAS D. KRISTOF, SPECIAL TO THE NEW YORK TIMES
Published: January 21, 1987

LEAD: Nothing that a Chinese host can put on a table has more cachet than a bowl of viscous bird’s nest soup. For centuries, it has been a delicacy throughout the Chinese world, a dish famed for its ability to keep people young and healthy.

Nothing that a Chinese host can put on a table has more cachet than a bowl of viscous bird’s nest soup. For centuries, it has been a delicacy throughout the Chinese world, a dish famed for its ability to keep people young and healthy.

But bird nests are becoming increasingly scarce. While the shortage is not yet a crisis, Chinese connoisseurs are obliged to pay more each time they bargain for nests - up to $1,000 a pound for top-quality nests.

‘’The price will definitely continue to increase,'’ Stephen Tam, owner of the Cheong Loong Swallow’s Nest store, said as he sorted the dozens of varieties of nests in his small shop here. ‘’Most places the birds live have been developed into farmland or towns, and that reduces the number of birds that are left.'’

In addition to the encroachment of humans on the birds’ habitat, pollution is eroding some of the cliffs where they live and build their nests. Meanwhile, rising prices are leading the ‘’harvesters'’ of nests to become more aggressive, sometimes snatching nests as soon as they are built, or grabbing nests that have eggs in them.

The nests used to make the soup belong to a kind of swallow, which builds on rocky cliffs or inside caves in several countries in Southeast Asia. Most of the nests today come from Indonesia, Thailand, Malaysia, Vietnam or China.

The nests are not, as most Americans assume, a thatch of twigs and grass such as a robin might manufacture. Rather, they are made of the birds’ saliva, which hardens into cementlike threads. When collected, the nests contain liberal amounts of feathers and even droppings, but are carefully washed and cleaned until they are white strips that look more like sponges than nests.

While swallow saliva soup may not send tingles across a Western palate, the Chinese rave over it. It is usually cooked with crab meat, shrimp or ham to make a gelatinous soup that is renowned principally for its healthfulness .

‘’The taste of the nests is nothing great,'’ said Fok Kam Tong, head chef at the Man Wah Restaurant in Hong Kong’s Mandarin Hotel, where a bowl of bird’s nest soup ranges in price from $14 to $38. That is why crab and other embellishments are added, he said.

But bird’s nest soup has virtues other than mere taste. ‘’It’s very good for you, very nourishing,'’ Mr. Fok added. ‘’It’s good for women, for their skin, so they don’t look old. But it’s not just for women; it’s good for everybody.'’

Mr. Fok disputes the pessimists who say that bird’s nest soup could eventually disappear. While scarcity of the proper nests is a concern, he and many Chinese food experts say, the resulting price increase would make it even more prized as a delicacy.

‘’If it becomes more expensive, it will be even more popular in Hong Kong,'’ said Sunny Lan Kun Ying, a salesman at Yuen Wo Bird’s Nest store near Hong Kong’s business district.

Not according to the owners of the small Hong Kong shops that sell bird nests, who say most people are being priced out of the market. The cost of bird’s nests has more than doubled in the last few years, they say, making it more difficult to afford a nest for a daughter with a skin blemish or a son who is about to take an important examination.

Some kinds of nests are becoming particularly rare, such as the red ones called ‘’blood nests.'’ These have a reddish tinge that chefs say derives from blood in the birds’ saliva. It is even better for one’s health than regular bird nests, they say.

So, while regular bird nests sell for about $500 for a catty - a Chinese unit of weight amounting to just over a pound - the best-quality blood nests sell for nearly $1,300 a catty at the most exclusive shops.

Meanwhile, the swallows are seeking more and more remote locations to build their nests in places where humans will not intrude. They must avoid not only youths who scamper along the cliffs or climb bamboo scaffolding to cave ceilings, but also monkeys that have been trained to climb the rock walls and retrieve nests.
‘’The swallows are very careful,'’ said Mr. Fok, the chef. ‘’They will never build a nest where it is easy to get to.'’

Add comment November 28th, 2007

Phylogenetic relationships of the Papuan Swiftlet Aerodramus papuensis and implications for the evolution of avian echolocation

darwin.biology.utah.edu
J. JORDAN PRICE, 1 * KEVIN P. JOHNSON, 2 SARAH E. BUSH 3 † & DALE H. CLAYTON 3 1 Department of Biology, St. Mary’s College of Maryland, St. Mary’s City, MD 20686, USA 2 Illinois Natural History Survey, Champaign, IL 61820, USA 3 Department of Biology, University of Utah, Salt Lake City, UT 84112, USA

© 2005 British Ornithologists’ Union The swiftlets (genera Aerodramus , Collocalia and Hydrochous ) are unusual among birds in that many species can orientate in complete darkness using echolocation. The position of the Papuan Swiftlet Aerodramus papuensis in this group has been uncertain historically, in part due to morphological differences between it and other swiftlets (it has three toes instead of the usual four) and a lack of data on its behaviour (there is uncertainty about whether it echolocates). Here we investigate the phylogenetic affinities of the Papuan Swiftlet using DNA sequence data from two mitochondrial genes, cytochrome b and ND2. We present evidence that it is able to echolocate but, unlike previously studied species that use echolocation primarily while flying in caves, A. papuensis uses this ability while active outside caves at night. We also provide new evidence for placement of the monotypic Waterfall Swiftlet Hydrochous gigas , a species that does not echolocate. Our data provide strong support for a basal relationship between A. papuensis and other Aerodramus taxa and suggest that this species and H. gigas are sister taxa, a relationship that would indicate paraphyly of the genus Aerodramus . Our phylogeny provides new insights into how echolocation has evolved in the swiftlets, in particular by indicating higher levels of homoplasy in this trait than was previously thought. Swiftlets (Apodidae: Collocaliini) are small, insectivorous birds found throughout the Australasian region from the Indian Ocean to the South Pacific. Most species roost and nest in caves, often placing their nests in areas of complete darkness, and are able to navigate using echolocation (Griffin 1958, Medway 1959, Medway & Pye 1977, Koon & Cranbrook 2002, Nguyen Quang et al . 2002). This unusual ability to echolocate is found elsewhere in birds only in the Neotropical Oilbird Steatornis caripensis , a species that also nests in caves (Griffin 1954, 1958). Unlike the ultrasonic cries of bats, the echolocation clicks of swiftlets are well within the human range of hearing (Cranbrook & Medway 1965), and so presumably do not allow the acuity needed to locate aerial insect prey. Rather, studies of several species indicate that echolocation is used in swiftlets primarily for avoiding obstacles while flying in darkness when visual cues are not available (Medway 1967, Griffin & Suthers 1970, Fenton 1975, Griffin & Thompson 1982, Collins & Murphy 1994). Most swiftlet species studied to date forage during the day and produce echolocation clicks mostly while flying through the caves in which they roost at night (Chantler & Driessens 1995, Chantler et al . 2000). The Papuan, or Three-toed, Swiftlet Aerodramus papuensis is unusual among the swiftlets in several ways. Most notably, it is the only known member of the Apodidae to have only three toes instead of the usual four (Chantler & Driessens 1995, Chantler et al . 2000). The hind toe, or hallux, is absent. Previous reports of this little-studied species also suggest that it might be active outside caves at night (Chantler et al . 2000), a behaviour not commonly reported in other swifts and swiftlets. Relationships between A. papuensis and other swiftlet taxa have *Corresponding author. Email: jjprice@smcm.edu †Present address: Natural History Museum and Biodiversity Research Center, The University of Kansas, Lawrence, KS 66045, USA.

© 2005 British Ornithologists’ Union, Ibis , 147 , 790–7been unclear, but morphological and putative behavioural differences indicate that this species is relatively distant from the rest. Whether or not A. papuensis is capable of echolocation has not previously been described (Medway & Pye 1977, Chantler & Driessens 1995, Chantler et al . 2000). Indeed, Nguyen Quang et al . (2002) note that echolocation is assumed to occur in all members of the genus Aerodramus ‘… except perhaps in the Three-toed Swiftlet, Aerodramus papuensis , a rare species of New Guinea whose ability to echolocate is still unknown.’ The manner in which echolocation has evolved in the Collocaliini is not yet fully understood, in part due to uncertainties about relationships within the group. The swiftlets are typically divided into three genera, Aerodramus , Collocalia and Hydrochous , based on such features as body size, plumage glossiness, nest features and a capacity to echolocate (Brooke 1972, Chantler et al . 2000). Recent phylogenetic studies with incomplete taxon sampling using mitochondrial DNA (mtDNA) sequence data are consistent with the monophyly of both Aerodramus and Collocalia (Lee et al . 1996) and that of the Collocaliini (Thomassen et al . 2003, Price et al . 2004). However, relationships of the single member of the genus Hydrochous , the Waterfall Swiftlet Hydrochous gigas , have remained unresolved (Lee et al . 1996, Thomassen et al . 2003), and affinities of several Aerodramus species, including A. papuensis , have not been analysed previously using molecular data. Until recently echolocation was thought to have evolved only once in the immediate ancestor of the Aerodramus clade. This view was based on the presence of echolocation in all studied members of this genus and a presumed lack of this ability in other genera (Brooke 1972, Medway & Pye 1977, Lee et al . 1996, Thomassen et al . 2003; but see Marin & Stiles 1993). The recent discovery of echolocation outside of the genus Aerodramus , however, in the Pygmy Swiftlet Collocalia troglodytes (Price et al . 2004), provides strong evidence against this idea. Echolocation has either arisen several times independently in the Aerodramus and Collocalia clades, or evolved once at the base of the swiftlet tree and was subsequently lost in some taxa. Resolving the phylogenetic position of H. gigas , which does not echolocate, could help in resolving the issue (Price et al . 2004). Furthermore, given the striking differences between the Papuan Swiftlet and other Aerodramus species, an examination of both the position of this unusual species on the swiftlet tree and its potential ability to echolocate is highly warranted. In this study, we investigate the relationships of the Papuan Swiftlet using sequence data from two mitochondrial genes, cytochrome b (cyt b ) and NADH dehydrogenase subunit 2 (ND2). We present evidence that this species is able to echolocate and, surprisingly, that it uses this ability while active outside caves at night. A new phylogeny for the swiftlets, which includes our molecular data from A. papuensis as well as a recently published cyt b sequence data from H. gigas (Thomassen et al . 2003), provides some new insights into how echolocation has evolved in these intriguing birds. METHODS A. papuensis individuals for molecular analyses and tape recordings of vocalizations were obtained by S.E.B. and D.H.C. on 18 November 2002, immediately outside the entrance to Losavi Cave ( c . 1350 m) near the village of Herowana in Eastern Highlands Province, Papua New Guinea (PNG). Birds were captured in flight using a 30-m mist-net, which was set at 22:00 h on 17 November and taken down at 03:00 h on 18 November. All A. papuensis individuals were captured in darkness between 02:00 and 03:00 h. We obtained tape recordings of vocalizations during this period using a Sony WM-D6C stereo cassette recorder and Sony ECM-Z70 electret condensor microphone. Birds were recorded while flying over the vicinity of the net, while struggling in the net and immediately upon release. Vocalizations were similar in all three conditions. DNA was extracted, amplified and sequenced for the mitochondrial cyt b (1058 bp) and ND2 (1078 bp) genes as described by Price et al . (2004). These sequences have been deposited in GenBank under accession numbers AY950787 and AY950788, respectively. Cyt b and ND2 sequences from other swiftlet taxa and from 15 species of swifts and treeswifts used as outgroups were obtained from Price et al . (2004) (GenBank accession numbers AY294424–AY294483 and AY204486–AY294545). We also obtained a cyt b sequence from H. gigas (1143 bp) from the study of Thomassen et al . (2003) (GenBank accession number AY135625). In all, we included mtDNA sequences from 62 individuals representing 40 species and subspecies of swifts and swiftlets. No significant incongruence was detected between the cyt b and ND2 genes using the partition homogeneity test (Farris et al . 1994, 1995, Swofford 2002, see also Price et al . 2004), so subsequent analyses

© 2005 British Ornithologists’ Union, Ibis , 147 , 790–796 combined the two genes. Both parsimony and maximum likelihood analyses of combined cyt b and ND2 data were conducted using PAUP* (Swofford 2002). We performed 100 random addition replicate heuristic parsimony searches to find the most parsimonious tree(s), then bootstrapped these data sets using 1000 replicates (Felsenstein 1985). For maximum likelihood, we computed the simplest model that could not be rejected in favour of a more complex model using Modeltest (Posada & Crandall 1998). These tests identified the GTR+I+G model as the favoured one for maximum likelihood analyses. We used ten random addition heuristic searches with TBR branch swapping to estimate the maximum likelihood tree. A maximum likelihood bootstrap analysis was then conducted with 100 bootstrap replicates and NNI branch swapping. Because ND2 sequences for H. gigas were not available for this study, we used cyt b sequences alone to estimate the phylogenetic position of this taxon following two approaches. First, we used the tree(s) recovered in the above parsimony and maximum likelihood analyses as a constraint (i.e. backbone) tree to which we added H. gigas , using only cyt b sequences in analyses to determine its position. As an additional comparison, we analysed the complete data set of cyt b and ND2 sequences under both parsimony and likelihood, coding the ND2 gene as missing data for H. gigas . Spectrograms of Aerodramus papuensis vocalizations were generated using Raven sound analysis software (Version 1.1, Cornell Laboratory of Ornithology, NY, USA, sampling frequency = 22.05 kHz, discrete fourier transform (DFT) size = 128 samples, frequency resolution = 248 Hz, time resolution = 5.8 ms, 99% frame overlap). Measurements of these sounds were compared with those measured previously for other swiftlet taxa (Price et al . 2004). On the basis of evidence for the presence of echolocation sounds in A. papuensis , we reconstructed the evolution of echolocation in the swiftlets by mapping the presence and absence of this character on our molecular phylogeny using simple parsimony in MacClade (Version 4.06, Maddison & Maddison 2003). RESULTS We captured 35 birds within a 1-h period from 02:00 to 03:00 h on 18 November 2002. Of these birds, toes were counted on 25 individuals. All 25 had only three obvious toes, but detailed examination of three of the 25 individuals revealed a vestigial hallux beneath the skin of the tarsus. Eight birds were prepared as museum skin (SEA 392–394, 396), skeletal (SEA 389, 395) or spirit (SEA 390, 391) specimens. Two of these (SEA 389, 395) were deposited in the PNG National Museum; the remaining specimens were deposited in the Museum of Natural History, University of Kansas (voucher number of tissue sample sequenced is SEA 389). During the previous day, 17 November, S.E.B. and D.H.C. carefully searched all accessible regions within Losavi Cave and found no evidence of A. papuensis individuals. No birds were seen or heard and no nests were found. The capture of so many individuals outside the cave later that night suggests that birds had been roosting or nesting nearby, perhaps under overhangs or in small tunnels outside the cave entrance. Parsimony and maximum likelihood analyses of cyt b and ND2 genes, excluding H. gigas , resulted in trees that were identical for relationships among Collocalia and Aerodramus species, including Aerodramus papuensis . Placement of A. papuensis as the sister taxon to all other Aerodramus received strong bootstrap support in all analyses (Fig. 1), with sequence divergences on the combined data set of 8.2–9.5% between A. papuensis and its congeners. Inclusion of cyt b sequences for H. gigas with the backbone tree either constrained (using cyt b data only) or unconstrained (using both cyt b and ND2) resulted in an identical position for this species as the sister taxon of A. papuensis, although this was not well supported in bootstrap analyses. Together these two species form the sister group to all other species of Aerodramus (Fig. 1). Phylogenetic relationships of other taxa were similar to those presented by Price et al. (2004). Sounds recorded from A. papuensis individuals flying at night (Fig. 2) were similar in their acoustic features to the echolocation sounds recorded in other Aerodramus species (Medway & Pye 1977, Suthers & Hector 1982, Thomassen et al. 2004) and in the echolocating Pygmy Swiftlet (Price et al. 2004). As in these other echolocating taxa, Papuan Swiftlets produced stereotyped double clicks, each of which consisted of two broadband pulses of sound separated by a short pause of 15–22 ms, the second click louder than the first. Recordings of echolocation clicks in other species have generally been made within their roost caves or while birds were flying through the cave entrance at dusk or dawn (e.g. Medway 1967, Fenton 1975, Medway & Pye 1977, Fullard et al. 1993, Collins & Murphy 1994, Price
© 2005 British Ornithologists’ Union, Ibis, 147, 790–796 et al. 2004). Our finding that A. papuensis uses echolocation while flying outside so late at night is therefore somewhat unusual. Reconstructing the presence of echolocation on our maximum likelihood tree (Fig. 3) shows the ancestors of the H. gigas/A. papuensis clade, those of the genus Collocalia and all ancestors shared between them as being equivocal for this character state. Echolocation has either been lost several times since its original appearance, been gained several times independently, or some combination of these possibilities. Figure 1. Most likely tree (–ln L = 17 444.605) resulting from combined unconstrained likelihood analyses of cyt b and ND2 sequence data using the GTR+I+G model with substitution rates A–C = 0.393, A–G = 13.588, A–T = 0.512, C–G = 0.188, C–T = 6.262, G– T = 1.000; base frequencies A = 0.330, C = 0.404, G = 0.065, T = 0.201; proportion invariant sites = 0.502; and shape parameter for the gamma distribution = 1.215. The sequence from the ND2 gene for Hydrochous gigas was counted as missing data. Numbers on branches indicate support from 100 bootstrap replicates (bootstrap values < 50% are not shown) and branch lengths are proportional to the number of substitutions.

© 2005 British Ornithologists’ Union, Ibis, 147, 790–796 DISCUSSION The Papuan Swiftlet Aerodramus papuensis has been considered conspecific with A. whiteheadi in the past (Chantler et al. 2000). Our results do not support this taxonomy. Rather, analyses of two mitochondrial genes using a variety of methods show A. papuensis as relatively distant to all other Aerodramus taxa. Similar to previous molecular studies of swiftlet phylogeny (Lee et al. 1996, Thomassen et al. 2003, Price et al. 2004), our results provide strong support for monophyly of the swiftlets (Collocaliini) and for the placement of Aerodramus and Collocalia as separate clades. Our finding of a sister relationship between A. papuensis and Hydrochous gigas, however, was surprising. Previous studies not including A. papuensis have suggested paraphyly of the genus Aerodramus by placing H. gigas within that clade (Lee et al. 1996, Thomassen et al. 2003); however, none of these previous results was well supported. Our placement of H. gigas, although also not strongly supported, is nevertheless the first to show this species at a consistent position using multiple analyses. Including ND2 sequence data in addition to cyt b will surely help in resolving the position of this enigmatic swiftlet. Distant molecular relationships between both A. papuensis and H. gigas in comparison with other swiftlet taxa are consistent with a variety of morphological and behavioural characters in which these birds are unique among the Collocaliini. For example, A. papuensis is the only swiftlet that has three toes instead of four. It is also one of the few species in this group reported to use echolocation while active outside of caves at night (although nocturnal activity has been reported in at least one other swiftlet, Aerodramus unicolor; Chantler et al. 2000). Similarly, H. gigas is much larger than most Aerodramus and Collocalia swiftlets (approximately 37 g vs. 14 g and 6.5 g, respectively; Lee et al. 1996) and is the only species that nests behind or near waterfalls (Medway & Wells 1976, Chantler & Driessens 1995, Chantler et al. 2000). Our finding that these two species are each other’s closest relatives was not predicted by morphology or known behaviours but was nevertheless supported by our molecular data (Fig. 1). Our maximum likelihood phylogeny suggests several possible scenarios for the evolution of echolocation Figure 3. Echolocation reconstructed onto the maximum likelihood phylogeny of the swiftlets. The presence or absence of echolocation in taxa other than Aerodramus papuensis and Hydrochous gigas are taken from Price et al. (2004).

© 2005 British Ornithologists’ Union, Ibis, 147, 790–796in the swiftlets (Fig. 3): (1) this ability arose once in the ancestor of the swiftlets and was subsequently lost in H. gigas and in the lineage leading to Collocalia linchi and C. esculenta; (2) it evolved at least three times independently in A. papuensis, C. troglodytes and ancestors of the rest of the genus Aerodramus; or (3) some combination of the previous two scenarios. Simple parsimony does not resolve which of these possibilities is most likely. Based on acoustic features, however, the orientation clicks of A. papuensis, C. troglodytes and most Aerodramus species are notably similar in comparison with sounds of other echolocating birds, a pattern that could indicate homology. In particular, the former taxa use double clicks with similar intraclick intervals (15–20 ms, Price et al. 2004), whereas oilbirds (Griffin 1958) and at least two other Aerodramus species (Medway & Pye 1977, Fullard et al. 1993) generally produce single clicks. Evidence suggests that all swiftlets and oilbirds have the capacity to produce both single and double clicks (Suthers & Hector 1982, 1985, Thomassen et al. 2004), so this similarity is not due solely to physiological constraints on click design. Furthermore, evolutionary losses of complex character traits such as echolocation are often thought to be more likely to occur than independent gains (Omland 1997, Cunningham et al. 1998), so it seems plausible that echolocation arose once and was lost twice on the swiftlet tree as opposed to alternative scenarios (e.g. gained three times, gained twice and lost once, etc.). Mapping echolocation onto our maximum likelihood phylogeny with losses made even slightly more likely than gains (losses 1.1× more likely) resolves the ancestor of the Collocaliini as having echolocation and supports the idea that this ability was lost in two separate lineages. These reconstructed patterns are altered, however, if H. gigas is moved to a position as sister taxon to all Aerodramus, a topology that favours the independent appearance of echolocation in Aerodramus and C. troglodytes. More phylogenetic data on H. gigas and additional methods of ancestral state reconstruction (e.g. Pagel et al. 2004) will be needed to help solidify our understanding of the evolution of echolocation in these birds. Echolocation presumably evolved in the swiftlets as an adaptation allowing birds to roost and nest in caves, away from most visually orienting predators or competitors (Fenton 1975, Medway & Pye 1977). The nesting ecology of swiftlet taxa, where known, is generally consistent with this idea. Nests of previously studied echolocating species, such as Collocalia troglodytes (Price et al. 2004) and a variety of Aerodramus taxa (Chantler & Driessens 1995, Chantler et al. 2000), are found most often in complete darkness within caves (but note that the A. brevirostris vulcanorum in Fig. 1 was one of several nesting in broad daylight in a volcanic crater in Java; D.H.C. pers. obs.). Non-echolocating species, by contrast, generally nest in areas exposed to daylight. For example, Collocalia esculenta and C. linchi nest on a variety of vertical substrates, including cliff faces, buildings and cave entrances (Fenton 1975, Chantler & Driessens 1995), and the aptly named Waterfall Swiftlet H. gigas builds its nests behind or near waterfalls (Medway & Wells 1976). If these species had cavenesting, echolocating ancestors, the loss of echolocation with the movement of these lineages out of caves suggests a cost to this ability, most likely in the form of developmental investments for the neural and structural specializations necessary for orientation by sound (Suthers & Hector 1982). The historical loss of echolocation would make sense in H. gigas, as the loud waterfalls near which it nests are especially ill-suited environments for echolocation. The nesting habits of A. papuensis remain unknown. However, our inability and the inability of previous investigators (reported in Chantler et al. 2000) to find nests of this species despite previous surveys of caverns, including Losavi Cave (M. Tarburton pers. comm.), suggests that, like H. gigas, this species might not nest inside caves. If so, the adaptive significance of echolocation in this bird would present somewhat of a mystery. Has echolocation been retained in this lineage from cave-nesting ancestors, and if so, why? The breeding and roosting behaviours of A. papuensis are subjects that clearly warrant further investigation. We thank Andy Mack, Avit Wako, Deborah Wright and Ross Sinclair of the Wildlife Conservation Society for logistical assistance in PNG, and Roger and Miriam Clayton for assistance in catching birds. Support during this work was provided by NSF grant DEB-0107947 to D.H.C., DEB0107891 to K.P.J and DEB-0118794 to D.H.C and K.P.J. REFERENCES Brooke, R.K. 1972. Generic limits in Old World Apodidae and Hirundinidae. Bull. Brit. Orn. Club 92: 53–57. Chantler, P. & Driessens, G. 1995. Swifts. A Guide to the Swifts and Treeswifts of the World. Sussex, UK: Pica Press. Chantler, P., Wells, D.R. & Schuchmann, K.L. 2000. Family Apodidae (Swifts). In Del Hoyo, J., Elliot, A. & Sargatal, J. (eds) Handbook of the Birds of the World, Vol. 5: 338–457. Barcelona: Lynx Edicions.

796 J. J. Price et al. Collins, C.T. & Murphy, R. 1994. Echolocation acuity of the Palawan swiftlet (Aerodramus palawanensis). Avocetta 17: 157–162. Cranbrook, Earl of & Medway, Lord. 1965. Lack of ultrasonic frequencies in the calls of swiftlets (Collocalia spp.). Ibis 107: 258. Cunningham, C.W., Omland, K.E. & Oakley, T.H. 1998. Reconstructing ancestral character states: a critical reappraisal. Trends Ecol. Evol. 13: 361–366. Farris, J.S., Kallersjo, M., Kluge, A.G. & Bult, C. 1994. Testing significance of incongruence. Cladistics 10: 315–319. Farris, J.S., Kallersjo, M., Kluge, A.G. & Bult, C. 1995. Constructing a significance test for incongruence. Syst. Biol. 44: 570–572. Felsenstein, J. 1985. Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39: 783–791. Fenton, M.B. 1975. Acuity of echolocation in Collocalia hirundinacea (Aves: Apodidae), with comments on the distributions of echolocating swiftlets and molossid bats. Biotropica 7: 1–7. Fullard, J.H., Barclay, R.M.R. & Thomas, D.W. 1993. Echolocation in free-flying Atiu swiftlets (Aerodramus sawtelli). Biotropica 25: 334–339. Griffin, D.R. 1954. Acoustic orientation in the oil bird Steatornis. Proc. Natl Acad. Sci. USA 39: 884–893. Griffin, D.R. 1958. Listening in the Dark. New Haven, CT: Yale University Press. Griffin, D.R. & Suthers, R.A. 1970. Sensitivity of echolocation in cave swiftlets. Biol. Bull. 139: 495–501. Griffin, D.R. & Thompson, D. 1982. Echolocation by cave swiftlets. Behav. Ecol. Sociobiol. 10: 119–123. Koon, L.C. & Cranbrook, Earl of. 2002. Swiftlets of Borneo: Builders of Edible Nests. Kota Kinabalu, Malaysia: Natural History Publications (Borneo). Lee, P.L.M., Clayton, D.H., Griffiths, R. & Page, R.D.M. 1996. Does behaviour reflect phylogeny in swiftlets (Aves: Apodidae)? A test using cytochrome b mitochondrial DNA sequences. Proc. Natl Acad. Sci. USA 93: 7091–7096. Maddison, D.R. & Maddison, W.P. 2003. MacClade: Analysis of Phylogeny and Character Evolution, Version 4.06. Sunderland, MA, Sinauer Associates. Marin, M.A. & Stiles, F.G. 1993. Notes on the biology of the Spot-fronted Swift. Condor 95: 479–483. Medway, Lord. 1959. Echo-location among Collocalia. Nature 184: 1352–1353. Medway, Lord. 1967. The function of echonavigation among swiftlets. Anim. Behav. 15: 416–420. Medway, Lord & Pye, J.D. 1977. Echolocation and the systematics of swiftlets. In Stonehouse, B. & Perrins, C. (eds) Evolutionary Ecology: 225–238. Baltimore: University Park Press. Medway, Lord & Wells, D.R. 1976. The Birds of the Malay Peninsula, 5. London: Witherby. Nguyen Quang, P., Yen Vo, Q. & Voisin, J. 2002. The WhiteNest Swiftlet and the Black-Nest Swiftlet. Paris: Socie�te� Nouvelle des E�ditions Boube�e. Omland, K.E. 1997. Examining two standard assumptions of ancestral reconstructions: repeated loss of dichromatism in dabbling ducks (Anatini). Evolution 51: 1636–1646. Pagel, M., Meade, A. & Barker, D. 2004. Bayesian estimation of ancestral character states on phylogenies. Syst. Biol. 53: 673–684. Posada, D. & Crandall, K.A. 1998. Modeltest: testing the model of DNA substitution. Bioinformatics 14: 817–818. Price, J.J., Johnson, K.P. & Clayton, D.H. 2004. The evolution of echolocation in swiftlets. J. Avian Biol. 35: 135–143. Suthers, R.A. & Hector, D.H. 1982. Mechanism for the production of echolocation clicks by the Grey Swiftlet, Collocalia spodiopygia. J. Comp. Physiol. 148: 457–470. Suthers, R.A. & Hector, D.H. 1985. The physiology of vocalization by the echolocating Oilbird, Steatornis caripensis. J. Comp. Physiol. 156: 243–266. Swofford, D.L. 2002. PAUP*: Phylogenetic Analysis Using Parsimony (*and Other Methods), Version 4.0. Sunderland, MA: Sinauer Associates. Thomassen, H.A., Djasim, U.M. & Povel, G.D.E. 2004. Echoclick design in swiftlets: single as well as double clicks. Ibis 146: 173–174. Thomassen, H.A., Wiersema, A.T., de Bakker, M.A.G., de Knijff, P., Hetebrij, E. & Povel, G.D.E. 2003. A new phylogeny of swiftlets (Aves: Apodidae) based on cytochrome-b DNA. Mol. Phyl. Evol. 29: 86–93. Received 21 October 2004; revision accepted 10 June 2005; first published online: 12 September 2005; DOI: 10.1111/j.1474-919x.2005.00467.x.

Add comment November 27th, 2007

Purple Martin, Swallows and Swifts of North America

surfbirds.com

Bird Feeders and Bird Food
Chimney Swift - small cigar-shaped body - flies fast and high over urban areas or low over lakes and rivers. Brown body. Twittering call.

In flight, this bird looks like a flying cigar with long slender curved wings. The plumage is a sooty grey-brown; the throat, breast, underwings and rump are paler. They have short tails.

Their breeding habitat is near towns and cities across eastern North America. Originally, these birds nested in large hollow trees, but now they mainly nest in man-made structures such as large open chimneys. The nest is made of twigs glued together with saliva and placed in a shaded location.
They are long distance migrants and winter in eastern Peru; other nesting locations in South America may exist. They migrate in flocks. This species has occurred as a very rare vagrant to western Europe. the gregarious nature of this species is reflected in that two individuals of this species turned up together on the Isles of Scilly.
These birds live on the wing, foraging in flight. They eat flying insects.
Their population may have increased with the availability of large chimneys as nesting locations. With suitable man-made habitat becoming less common, their numbers may be declining in some areas.

Photo © Quelennec Thierry

urple Martin - large swallow. Nests communally. See how to attract Purple Martins

Adult males are a glossy dark purple, and adult females are dark on top with some purple on the back, and lighter underparts. Juveniles are greyish-brown above and whitish below, gaining some purple feathers by their first winter.
Their breeding habitat is open areas across eastern North America, and also some locations on the west coast from British Columbia to Mexico. This species typically breeds in colonies.
The eastern nominate race nests exclusively in man-made bird houses, of which about a million are provided. It is the only bird totally dependent on humans for nest sites. It is important to note that unmonitored Purple Martin houses often become breeding colonies for House Sparrows and Starlings - invasive species responsible for the decline of the Eastern Bluebird and Red-headed Woodpecker respectively. Purple Martins will not nest in such a site until the House Sparrows and Starlings are removed. In severe infestations, it is best to take down the Purple Martin house or plug the entrance holes.
The paler subspecies P. s. hesperia of Arizona and western Mexico uses only woodpecker holes in Saguaro and other large cacti, and the large pale west coast form P. s. arboricola utilises woodpecker and other natural cavities as well as nesting boxes and gourds.
The Purple Martin migrates to the Amazon basin in winter. The first record of this species in Europe was a single bird on Lewis, Scotland on 5-6 September 2004, and the second was on the Azores on 6 September 2004.
These birds hunt for insects in flight, although sometimes they will pick up insects off the ground. They usually fly relatively high, so, contrary to popular opinion, mosquitos do not form a large part of their diet.
The call is a gurgly tchew-tchew.

Photo © Tim Avery

Tree Swallow - white below and blue above.

This swallow averages 13.5 cm (5 inches) long and weighs about 20g. The bill is tiny. The adult Tree Swallow has iridescent blue-green upperparts, white underparts, and a very slightly forked tail. The female usually has duller colours than the male, often more greenish than the more bluish male. The juvenile plumage is dull grey-brown above and may have hint of a gray breast band.

Tree Swallows nest in natural or artificial cavities near water and are often found in large flocks. They also readily nest in nest boxes maintained by people, often for Eastern Bluebirds.
The Tree Swallow nest consists of multiple layers of small twigs and grasses and is lined with large feathers. (As such, it is easy to differentiate from that of an Eastern Bluebird.) The female lays 4 to 6 white eggs and incubates them by herself. The eggs hatch in about 14 days and the hatchlings are not precocious and need to be fed by both parents. The hatchlings typically fledge in 16-24 days.
Tree swallows have only one brood in a year.
They subsist primarily on a diet of insects, sometimes supplemented with small quantities of fruit. Tree Swallows are excellent fliers and take off from their perch and acrobatically catch insects in their bills in mid-air.

Photo © Ryan Sayers

Barn Swallow - white below and blue above but with a red throat.

Barn Swallows are similar in habits to the other aerial insectivores, including the other related swallows and martins and the unrelated swifts (order Apodiformes). They are not particularly fast flyers (estimated at about 11 m/s [1]), but show remarkable manoeuvrability, necessary to feed on flying insects while airborne. They are often seen flying relatively low in open or semi-open areas.
Barn Swallows build neat cup-shaped nests constructed of mud collected in their beaks. The inside of the nest is lined with grasses, feathers and other soft materials. They normally nest in accessible buildings such as stables or under bridges and wharves. Before these types of sites became common, they nested on cliff faces or in caves. The female typically lays 4 or 5 eggs. Both parents build the nest and feed the young.
The numbers in North America increased during the 20th century with the increased availability of man-made nesting sites. In recent years, there has been an ongoing gradual decline in numbers in parts of Europe and North America, due to agricultural intensification reducing the availability of insect food. However, it remains widespread and fairly common in most parts of its range.

Photo © Simon Woolley

Cliff Swallow - similar to Barn Swallow but has short square tail and reddish rump.

It breeds in North America and Mexico, and is migratory, wintering in southern South America. This species is a very rare vagrant to western Europe.
These birds average 5 inches long with a tiny bill. The adult has an iridiscent blue back and crown, brown wings and tail, and buff rump. The nape and forehead are white. The underparts are white except for a red face. The tail is square-ended.
Young birds are essentially brown above and whitish below, except for the buff rump and dark face.
The only confusion species is the closely related Cave Swallow, which is richer in colour and has a cinnamon rump and forehead.
Cliff Swallows breed in large colonies. They build conical mud nests and lay 3-6 eggs. The natural nest sites are on cliffs, preferably beneath overhangs, but as with the Eurasian House Martin, man-made structures are now the principal locations for breeding. Female Cliff Swallows are known to lay eggs in and move previously laid eggs into the nests of other birds within the colony.
This species has always been plentiful in the west of North America, where there are many natural sites, but the abundance in the east has varied.
European settlement provided many new nest sites on buildings, but the population declined in the late nineteenth and early twentieth centuries as the supply of unpainted barns declined. There has been a subsequent revival as dams and bridges have provided suitable sites. These are the famous swallows that return every year to the Mission San Juan Capistrano in California on (or around) March 19.
Like all swallows and martins, Cliff Swallows subsist primarily on a diet of insects which are caught in flight.

Photo © Alan Henry

Add comment November 26th, 2007

BREEDING OBSERVATIONS OF CAVE SWALLOWS (HIRUNDO FULVA)

elibrary.unm.edu
AT TWO CUBAN SITES Salvador Peris1 & A. Llanes2 1Department of Animal Biology-Zoology, Faculty of Biology, University of Salamanca, 37071 Salamanca, Spain. 2Institute of Ecology and Systematic. Ministry of Science, Technology and Environment of Cuba. Key words: Hirundo fulva, breeding, eggs, nest, Cuba.

INTRODUCTION Following to Ridgely & Tudor (1989), we considered the Cave Swallow (Hirundo fulva) as a species distinct from the Chesnut-collared Swallow (H. rufocollaris), which has breeding populations in Ecuador and Peru�. The Cave swallow breeds in Central America, the Caribbean and in the southern U.S. The species is widely distributed in Cuba and the Juventud Isle (fomerly called Isle of Pines), where it breeds on farm-houses, factories, sea cliffs and in natural caves (Bond 1990), wintering in small flocks in the country (Garrido 1988). In spite of its relative abundance, little is known of its breeding biology in the Caribbean. The aim of this study is to provide information on the breeding biology of two Cave Swallow populations in two different habitats of central Cuba. STUDY AREA AND METHODS Observations were made in the caves of Beruvides-Sebastia�n, located 1.5 km east of the village of Agramonte (22°40’N, 81°08’W), province of Matanzas (central Cuba). The other colony, also located in the Matanzas province, was situated on a high factory building in San Antonio de Los Baños (23°03’N, 81°31’W). Both localities are situated in a mixed urban-agricultural area. The colonies were monospecific, without association with other swallow species, as has been fund elsewhere (Huels 1985). The caves of Agromonte have numerous escarpments, which the swallows use to attach their nests. The nests of the San Antonio colony are fund on the top of roof beam. In both colonies, a mist-net 9 x 2 m, was set up during the morning at the entrance of the caves and building, from 20 March to 22 December 1993; a total of 215 birds were captured. Most of the birds were weighed, measured, banded with a U.S. Fish & Wildlife Service aluminum ring and released afterwards. The following measurements were taken 210 following Svensson (1984): wing length (flattened and straightened), tail, tarsus length and bill length (from the nostrils to the tip of the bill). In April, the birds were sexed using as criteria the presence or absence of an incubation patch and the morphology of the cloacal protuberance. Nest measurements included height above the ground, external maximum diameter, internal maximum diameter and depth of the nest �s concavity. Eggs were measured (length and width) with a slide caliper to the nearest 0.1mm. Egg weight was obtained by a Pesola balance to the nearest 0.5 g and only in the first three incubation days. Statistical analysis was carried out with two-tailed tRESULTS AND DISCUSSION Measurements and morphology of the breeding birds. No apparent sexual dimorphism was found in plumage characters. Although males were slightly larger than females, no significant differences (mean ± SD; P > 0.05) were found between the sexes in body mass: male 17.6 g ± 1.2, female: 17.6 g ± 1.4; wing lenght: male 102.1 mm ± 0.2, female: 101.3 mm ± 0.1; tail length: male 41.0 mm ± 0.2, female 41.4 mm ± 0.2; tarsus length (12.7 mm ± 0.0) and culmen length (5.5 mm ± 0.0), nor between the birds from the two study localities. Brood patches were present in all the females captured from late April to early August. This patch is not so well developed in males, being a useful character in sexing swallows (Fig. 1). Cloacal protuberance is only slightly marked in females, but it is well developed in males (Fig. 1), being also a good character for sex discrimination during the breeding season (late April to early August). The eggs size were measured only in one locality (Agromonte): mean length = 20.5 mm ± 0.1 (CV = 5.0), width: 14.5 mm ± 0.1 (CV = 3.2), and fresh weight = 2.1 g ± 0.2 (CV = 1.9). Molting of the inner primaries began in both sexes from early-middle June to middle December, reaching its maximum during September and October, when all the captured birds were moulting (Fig. 2). Comparison between nests in natural caves and factory buildings. Median height of the nests above the ground in natural caves was very similar to those measured in buildings (Table 1). Nests from the human settlements in San Antonio have significantly larger diameters and width than these situated in the caves (Table 1). Depth and height of the nests were similar in both localities, but which a statistically significant differences in width (Table 1). FIG. 1. Percentage of occurrence of cloacal protuberance and brood patch according to seasons, in breeding Cave Swallows from Matanzas (central Cuba). FIG. 2. Percentage of Cave Swallow individuals molting in Matanzas, central Cuba.
Although height and depth are important parameters in nest-boxes nesting birds in order to increase the number of eggs and nestlings (East & Perrins 1988, Pascual 1994), also the nest width could implicate differences in clutch size. Unfortunately, clutch size in the San Antonio colony was impossible to record and no comparisons with the Agromonte colony (with an average clutch size of two eggs by nest) are possible. The larger structural dimensions of the nests in the factories may be due to their support on beam-buildings with the need of larger and more robust nest-material on these structures without walls. In contrast, the nests on natural depressions are firmly attached to the rocky walls and do not need the support of large material. However, Martin & Hector (1988) observed the use of wool as a lining material in the nest of cave swallows in Texas (US) with potential negative effects on the breeding perfomance of the birds due to lack of proper nestling thermoregulation. In our populations no lining material of human origin was observed, in spite of the nearby high population density in both localities. However, if temperature has an indirect effect on nest-building (Elkins 1983) the differences found in nest �s size could indicate the warmer environment of the buildings, and a need for larger nest structure in order to avoid hyperthermia, in comparison with the natural caves. ACKNOWLEDGMENTS Manuscript was improved by an anonymous reviewer. Partial funding was provided by the Instituto de Ecologi�a & Sistema�tica, Ministry of Science, Technology & Environment of Cuba and the Universidad de Salamanca of Spain. REFERENCES Bond, J. 1990. Birds of the West Indies. Collins, Hong-Kong. East, M. L., & C. M., Perrins.1988. The effect of nestboxes on breeding populations of birds in broadleaved temperate woodlands. Ibis 130: 393–401. Elkins, N. 1983. Weather and bird behaviour. Poyser, Calton, U.K. Fowler, J., & L. Cohen. 1987. Statistics for ornithologist. BTO Guide 22. Tring, U.K. Garrido, H. H. 1988. La migracio�n de las aves en Cuba. Publ. Asoc. Amigos de Doñana no 0. Sevilla. Huels, T. R. 1985. Cave Swallow paired with Cliff Swallows. Condor 87: 441–442. Martin, R. F., & D. Hector.1988. Nest lining with sheep wool. Potential negative effects on cave swallows. Wilson Bull. 100: 294–296. Pascual, J. A. 1993. Ocupacio�n de distintos modelos de nidal por el Estornino negro (Sturnus unicolor). Doñana Act. Vertebrata 20: 165–178. Ridgely, R. S., & G. Tudor. 1989. The birds of South America. The oscine passerines. Univ. ofTexas Press, Austin, Texas.

GENERAL BIOLOGY Svensson, L. 1975. Identification guide to European passerines. Naturhistoriska Riskmuseet, Stockholm. Accepted 12 February 1998.

Add comment November 23rd, 2007

Bird’s nest,Crab Meat &Winter Melon Soup

ediblebirdnest.com
Ingredients :
113 g Superior bird’s nest
450 g winter melon
38 crab meat
2 cups stock
1 egg white
1 slice ginger

Seasoning :
1/3 tsp salt
1 tsp caltrop starch
2 tbsp stock

Method :

1. Drain bird’s nest. Remove pell from winter melon. Then remove pith and cut into pieces.

2. Bring stock to the boil. Add ginger slice and winter melon. Cook for 10 minutes. Then cover for 10 more minutes. Discard ginger slice. Add winter melon into the blender. Process into winter melon puree.

3. Add bird’s nest into winter melon puree and bring to the boil. Stir in crab meat, seasoning and egg white. Serve.
 

Add comment November 22nd, 2007

Experimental manipulation of tail length in female barn swallows (Hirundo rustica) affects their future reproductive success

beheco.oxfordjournals.org
Previous studies have shown no significant effect of experimental tail length manipulation in female barn swallows (Hirundo rustica) at the beginning of a breeding season on reproductive success or behavior during that breeding season.

In the present study, we investigate if tail length manipulation had any effect on reproductive performance the following year, the so-called long-term effect, in contrast to the short-term effects already studied. We found that females with experimentally elongated external tail feathers at the beginning of a breeding season produced less offspring during the breeding season the following year than did females with shortened or unmanipulated tails. These results suggest that tail elongation caused flight deficiencies that deteriorated the condition of females and eventually reduced reproductive success. The finding of long-term effects but no significant short-term effects for female tail elongation suggests that female barn swallows have the ability to adjust immediate parental investment. Detrimental effects of long tails in females in terms of decreased reproductive success might explain why female tails are not as long as those of males. Finally, females mated to long-tailed (sexually attractive) males decreased their reproductive success the following year more than did females mated to short-tailed males, possibly owing to differential parental effort causing a deterioration of their condition.

Key words: external tail feathers, life history, reproductive success, tail length manipulation, tradeoffs between life history and sexual selection.

  INTRODUCTION

Sexual selection (i.e., any phenotypic variation nonrandomly related to variation in mating success) often explains the presence of apparently nonadaptive traits in many animal species (Darwin, 1871). Secondary sexual characters might be detrimental in terms of survival, but if they confer mating advantages, they could pass to the next generation. Typical examples of sexually selected traits are the exaggerated long male tails of many birds (Andersson, 1994). Experimental manipulations of tail length proved two decades ago that long tails in male long-tailed widowbirds (Euplectes progne) conferred mating advantages (Andersson, 1982). Another bird species with long tails and intensively studied is the barn swallow (Hirundo rustica), but in this case, the function of long tail streamers has been the subject of a long debate (see Barbosa and Møller, 1999; Evans, 1998; Evans and Thomas, 1997; Hedenström, 1995; Hedenström and Møller, 1999; Møller et al., 1998; Thomas and Rowe, 1997). Some researchers support the hypothesis that the external tail feathers may have been elongated exclusively by means of natural selection processes, because long tails may provide some advantages in flight performance (Norberg, 1994). On the other hand, much evidence has been accumulated that supports the hypothesis that sexual selection has played and still plays an important role in the evolution and maintenance of external tail feathers in male barn swallows (Møller, 1988; for a review, see Møller et al., 1998). Some authors consider that both natural and sexual selection could have contributed to the elongation of external tail feathers (Buchanan and Evans, 2000; Rowe et al., 2001).

 Most studies trying to identify the function of external tail feathers in the barn swallow have focused on males; much less attention has been paid to females. Until very recently, the study of presumed ornamental traits in females of avian species has been a neglected topic (for a review, see Amundsen, 2000). In barn swallows, females also have considerably long tails, longer than those of juveniles of the two sexes, but significantly shorter than males (Cramp, 1988; Møller, 1994). There is no agreement if tail length in female barn swallows is the optimum according to natural selection (Hedenström and Møller, 1999; Møller et al., 1998), or if it has been elongated beyond that optimum by sexual selection (Buchanan and Evans, 2000; Rowe et al., 2001). An observational study with large sample size (Møller, 1993) suggested that tail length in female barn swallows could be considered a sexual ornament because it reliably reflected female reproductive potential, and because males mated to long-tailed females achieved a selective advantage. However, an experimental study in a different population (Cuervo et al., 1996a) did not find any evidence for tail length in females being an ornament. Cuervo et al. (1996a) assumed that tails in female barn swallows were longer than the optimum according to natural selection, because females had longer tails than juveniles. Tail elongation in females could have been a consequence of strong directional female preference for long-tailed males if there is a strong genetic correlation between the character in the two sexes (correlated response hypothesis; Lande, 1980; Lande and Arnold, 1985). Another possibility is that long tails also confer mating advantages to females (ornament hypothesis). If this is the case, long tails in females could reflect either reproductive or parenting ability (Hoelzer, 1989), genetic quality (Iwasa et al., 1991; Zahavi, 1975), or simple attractiveness (Fisher, 1930; Pomiankowski et al., 1991). Cuervo et al. (1996a) manipulated the length of external tail feathers, but they did not find any evidence that male mating preferences depended on female tail length, thus supporting the correlated response hypothesis for the existence of exaggerated long tails in females. Moreover, they found that neither experimental treatment (elongation or shortening of external tail feathers) nor original female tail length previous to the treatment had a significant effect on a number of reproductive variables: start of laying, offspring provisioning, total number of eggs, and total number of fledglings.

In an attempt to understand the function of the external tail feathers in female barn swallows, as well as the evolutionary forces that have driven their evolution, Cuervo et al. (1996b) also calculated daily energy expenditure in the females with experimentally manipulated tail length. They used the doubly labeled water technique that measures respiration rates, specifically carbon dioxide production, and allows calculation of estimates of energy expenditure (Bryant, 1989). If tail length is optimal according to natural selection, any tail length modification will impair flight performance and will cause either a change in behavior or an increase in energy expenditure. On the other hand, if tail feathers have been elongated by sexual selection beyond the optimum according to natural selection, experimental elongation of tails will also impair flight efficiency. However, experimental shortening might reduce tails to a length closer to the natural selection optimum, and flight performance would then improve. Cuervo et al. (1996b) found no significant evidence for behavioral changes in the birds involved in the experiment. Surprisingly, experimental treatment had no significant consequences on energy expenditure, although both natural and sexual selection hypotheses predicted some effect of tail length manipulation on flight performance and on energetic costs. Females of other avian species have also shown no change in energy expenditure owing to flight costs (Moreno et al., 1999). Probably, assessing energy expenditure during a short period of time (24 h) was not the most appropriate method to detect costs of tail length manipulation.

Given that no significant differences were found among the three experimental groups of female barn swallows with very different tail length, can we conclude that tail length manipulation in females does not have any effect on flight performance? There is an important factor that we have not considered, because barn swallows may be able to adjust their effort in the short term. However, if tail length manipulation impairs flight performance, and barn swallows adjust their effort to balance flight deficiencies, this extra effort will have long-term consequences. It has been already shown in male barn swallows that tail length manipulation had a long-term effect, because survival decreased with tail elongation and increased with tail shortening (Møller and de Lope, 1994). This finding supports the assumptions that (1) long tails are costly in males and (2) tail length manipulation may have long-term effects. Most remarkable, survival cost of tail length manipulation was related to original tail length, with naturally long-tailed males being better able to survive tail elongation, and naturally short-tailed males benefiting more from tail shortening (Møller and de Lope, 1994). In another study, male barn swallows had tail length experimentally manipulated, and a number of fitness components were examined the following year (Møller, 1989). Males with elongated tails produced significantly fewer fledglings the following year, and some other traits also showed significant deterioration. No significant differences were found between males with shortened and unmanipulated tails.

As we found no significant effect of tail length manipulation on behavior or reproductive success of female barn swallows in the year when the experiment took place (Cuervo et al., 1996a,b), we have now studied exactly the same individuals the following year. Our aim was to assess possible long-term consequences of the manipulation. We presumed that survival, tail length, or reproductive performance might have been affected. In case of finding an effect of tail manipulation, we would be able also to better understand the forces that may have affected the evolution of the external tail feathers in female barn swallows.

METHODS
Barn swallows are small insectivorous passerines (approximately 20 g) that feed on the wing. Sexual dimorphism is slight, with the exception of the external tail feathers, which are generally longer in males than in females. They are mostly socially monogamous, build nests out of mud and vegetal fragments associated with human constructions, and may have two or even three clutches per year. Populations breeding in Europe winter in Africa south of Sahara, and arrive at the breeding grounds between February and April, depending on latitude. Tail feathers are molted once every year in the winter quarters (for more information on the species, see Cramp, 1988; Møller, 1994). This study was carried out at Badajoz, southwestern Spain, in 1994 and 1995. The field area consists of agricultural land with scattered groups of trees (de Lope, 1983). Swallows bred in farm rooms, getting permanent access through open doors and windows. Swallows included in this study bred colonially in three farms located less than 5 km apart. Morphological measurements or reproductive performance of female swallows did not differ among farms (Cuervo et al., 1996a), and consequently, we pooled the data from the three farms for subsequent analyses.

In 1994 and 1995, swallows were caught early after arrival to the breeding area by using mist nets at doors and windows at dawn. Every individual was measured and provided with a numbered metal ring and a unique color combination of plastic rings. Measurements included both right and left external tail feather length, and the mean of the two feathers was considered the length for that character. Every nest was visited at least once a week throughout the breeding season to determine parent identity, date of laying, number of eggs, and number of nestlings. In 1994 all female swallows, when captured the first time, were randomly assigned to one of three experimental treatments: shortened, elongated, or unmanipulated external tail feathers. External rectrices were shortened by cutting a 20-mm-long piece 10 mm from the base of the feather and gluing back the apical part to the original base using cyanoacrylate super glue. For elongation, the feathers were cut 10 mm from the base, and the 20 mm long piece of feather from the shortened group was glued between the apical and the basal pieces. In both treatments, junctions were strengthened by inserting a small piece (approximately 2 mm long) of fine entomological pin into the pulp cavity of the rachis. Females with unmanipulated tails were captured and measured in the same manner as the others. We did not include a second control group in the experiment, cutting and gluing back the feather without change of length, because previous studies had shown that treatment itself had no effect (Møller, 1988, 1992). Although shortened feathers had one junction and elongated feathers had two, we considered the effect of another piece of pin minute and negligible, in agreement with other authors (Smith and Montgomerie, 1991). Only females captured before 27 March were included in the analyses, because we did not manipulate tail length of individuals that arrived late to the breeding area.

Barn swallows show high breeding philopatry (Cramp, 1988; Glutz von Blotzheim and Bauer, 1985), and individuals breeding in 1994 but absent in 1995 were considered to be dead. In other words, we estimated survival from the return rates to the breeding area, as in previous studies (Møller, 1994; Møller and de Lope, 1999). Less than 1% of adults have ever returned 1 year without having been captured the previous year, a result based on more than 1000 adults recaptured (de Lope F, Szép T, and Møller AP, unpublished data). This ensures that our assumption does not cause any important bias in the results. Although we do not know the exact date each individual arrived at the breeding area, we assume that it is highly related to the date of first capture, because between mid February and the end of March all individuals were captured at least every week. We determined the number of nestlings when they were ringed, 12–14 days old. We assume that this number reflects the number of fledglings, because nestling mortality is very rare among nestlings of that age (chicks leave the nest when 3 weeks old).

Statistical analyses were performed according to Sokal and Rohlf (1981) and Siegel and Castellan (1988). A logistic regression (Hosmer and Lemeshow, 1989) was used to test if experimental treatment had a significant effect on female survival. Tail length and dates were log10-transformed before parametric analyses. Total number of eggs or nestlings were considered as ordinal discrete variables and were analyzed using nonparametric statistical tests. All statistical tests were two-tailed, and the level for significance was.05.

RESULTS

In 1994 we included 48 female barn swallows in the experiment: 15 with elongated tails, 16 with shortened tails, and 17 unmanipulated. From these 48 individuals, only 27 survived to the following year, nine for each experimental treatment. Two of the females alive in 1995 did not breed, however. Proportion of ages in 1994 (1 year old/more than 1 year old) for the 27 surviving females according to treatment was as follows: shortened, two to seven; unmanipulated, three to six; and elongated, one to eight. These proportions do not differ significantly from one another (G test, Gadj = 1.19, df = 2, p =.57).

A multiple logistic regression was used to analyze if experimental treatment had an effect on female survival while controlling for the possible effect of original tail length of females in 1994 and male tail length in 1994. None of these variables showed a significant effect on female survival (final value = 30.92, 2 = 3.95, df = 3, p =.27; in all three partial effects, -.85 t44 1.70, p .10). It is important to include male tail length in the analysis because female reproductive effort depends on the degree of ornamentation of their mates (de Lope and Møller, 1993), and tail length is an ornamental trait in males (Møller, 1988). We repeated the analysis, including in the model the quadratic term of male and female tail length, in order to test if the relationship was curvilinear, but the result was qualitatively similar.

Female tails were longer in 1995 (mean ± SE = 86.41 ± 1.00 mm, n = 27) than in 1994 (mean ± SE = 85.47 ± 1.09 mm, n = 27; paired t test: t = -2.91, df = 26, p =.0074). Tail lengthening did not differ between 1-year-old (mean ± SE = 0.29 ± 0.75 mm) and more than 1-year-old females (mean ± SE = 1.12 ± 0.36 mm; t test: t = -1.07, n1 = 6, n2 = 21, p =.30). This result is not completely in accordance with previous observations in a different population in which female swallows only increased significantly tail length from the first to the second year of life (Møller, 1991). To analyze the possible effect of experimental treatment on female tail length the following year, we did an ANCOVA with female tail length in 1995 as the dependent variable, female tail length in 1994 as the covariate, and experimental treatment as the grouping variable. Although tail length in 1995 was closely related to tail length in 1994 (F = 288.18, df = 1,23, p <.001), the effect of the treatment did not reach significance (F = 2.75, df = 2,23, p =.085). Adding male tail length in 1994 to the model gave qualitatively similar results.

To compare phenology of reproduction among experimental groups and between years, we used the date of laying of the first egg. In 1995 females delayed the beginning of reproduction in relation to 1994 (paired t test: t = -3.08, df = 24, p =.0052). By using ANCOVA, we found that breeding dates in 1995 were related to breeding dates in 1994 (F = 28.06, df = 1,21, p <.001) but were not related to experimental treatment (F =.22, df = 2,21, p =.81). Adding male tail length in 1994 to the model gave qualitatively similar results.

Since we cannot consider total number of eggs laid during the breeding season or total number of nestlings as continuous variables, we cannot use parametric tests as done above. We have simply compared the difference in number of eggs laid by each female in 1995 and 1994 among experimental groups. Females laid fewer eggs in 1995 than in 1994 (Wilcoxon signed-rank test: n = 25, z = 3.30, p =.0010), but the decrease in number of eggs did not differ significantly among groups with different tail treatment (Kruskal-Wallis test: KW = 1.27, n1 = n2 = 8, n3 = 9, p =.53). Total number of nestlings produced by each female was also smaller in 1995 than in 1994 (Wilcoxon signed-rank test: n = 25, z = 2.32, p =.020), on average 2.56 nestlings less in the whole season. However, the decrease in the total number of nestlings (1995 minus 1994) differed significantly among experimental groups (Kruskal-Wallis test: KW = 7.59, n1 = n2 = 8, n3 = 9, p =.023). More specifically, females with elongated tails had a reduced number of nestlings the following year compared with that of females with shortened (Mann-Whitney test: U = 60.5, n1 = 8, n2 = 9, p = .017) or unmanipulated tails (U = 59.5, n1 = 8, n2 = 9, p =.022). We found no significant difference in number of nestlings between females with shortened and unmanipulated tails (U = 35.5, n1 = n2 = 8, p =.71) (Figure 1).
In the previous analyses concerning variation between years in number of eggs and nestlings, we have not controlled for male tail length, an important character that could influence female reproductive effort (de Lope and Møller, 1993). Therefore, we have explored if male tail length was related to the decrease in reproductive success experienced by females in 1995 relative to 1994. Variation in total number of eggs was not significantly related to tail length of males in 1994 (Kendall rank-order correlation: T = -.035, n = 25, p = .81) or in 1995 (T = -.014, n = 25, p =.92). Variation in total number of nestlings was not significantly related to tail length of males in 1995 (T =.021, n = 25, p =.88), but we found a statistically significant negative relationship between the decrease in number of nestlings and male tail length in 1994 (T = -.365, n = 25, p =.010). That is, females paired to long-tailed males in 1994 had decreased production of nestlings the following year compared with that of females mated to short-tailed males (Figure 2). The significant differences among experimental groups in the decrease of total number of nestlings may be influenced by original tail length of males. Therefore, we tested whether male tail length differed among treatments in 1995 and 1994. Differences in male tail length among experimental groups were far from significant in 1995 (Kruskal-Wallis test: KW = 0.26, n1 = n2 = 8, n3 = 9, p =.88) and 1994 (KW = 0.63, n1 = n2 = 8, n3 = 9, p = .73; we have only included males whose females bred also in 1995). Thus, we can conclude that the relationship between decrease in number of nestlings and male tail length in 1994 was not confounded by treatment.

DISCUSSION

Previous studies have shown that experimental tail length manipulation in female barn swallows at the beginning of a breeding season caused no significant change in female parental behavior and reproductive success during that breeding season (Cuervo et al., 1996a,b). However, we have found some effects of the manipulation the following year, the so-called long-term effects, in contrast to the short-term effects during the same year. Females whose external tail feathers were experimentally elongated in 1994 produced less fledglings in the breeding season of 1995 than did females with shortened or unmanipulated tails. This result suggests that tail elongation in female barn swallows caused flight deficiencies and had, indeed, a detrimental long-term effect. This implies that female barn swallows have the ability to adjust parental investment. They can balance imposed handicaps, maybe by making an extra effort, and continue for a certain time with normal levels of parental investment. However, present extra effort will lead to a future cost. We found a convincing reason why female barn swallows do not have longer tail feathers: Although mating advantages of long-tailed females have never been confirmed (Cuervo et al., 1996a), here we show detrimental effects of long tails in terms of decreased reproductive success. For long tail feathers in males, both advantages (Møller, 1988, 1992; Saino et al., 1997) and disadvantages (Møller and de Lope, 1994; Møller et al., 1995) have been found. Differential selective forces on male and female barn swallows may thus have given rise to the current sexual dimorphism in tail length. Moreover, reduced reproductive success owing to female tail elongation could be also interpreted as a selective force weakening sexual selection for tail lengthening in females. Interestingly, male tail length would be also affected if, as it seems to be the case, there is a significant genetic correlation between the sexes for that character (Møller, 1993). The trade-off between ornamentation and parental investment has been largely discussed in the literature (Fitzpatrick et al., 1995), and some theoretical models have shown that expression and honesty of ornaments will depend on marginal fitness gains of advertisement effort (Kokko, 1998).

It is interesting to notice that tail elongation had significant effects on reproductive success the following year, but not on survival. Similar experiments in male barn swallows have found that tail elongation diminished survival probability (Møller and de Lope, 1994). Even if tail elongation had an effect on female survival that we have not detected, our results suggest that reproductive success is more sensitive to small changes in condition than is survival. Moreover, barn swallows may live for 5 years or longer (Møller and de Lope, 1999), and there is probably a trade-off between current effort in reproduction and survival prospects (Saino et al., 1999). Barn swallows should have the ability to maximize reproductive effort while not seriously compromising survival. We have also found that experimental tail length manipulation in 1994 did not significantly affect date of laying of the first egg or number of eggs laid during 1995. This implies that differences in number of fledglings among treatments were not caused by differences in phenology or in number of eggs. Maybe poor condition is only expressed in the most energy demanding activities. Provisioning of young is generally considered to be the most energy demanding activity of parental care (Clutton-Brock, 1990; Winkler and Wilkinson, 1988), which could explain why there was no significant effect of experimental treatment on number of eggs, but the effect was notable for number of fledglings.

Both natural and sexual selection hypotheses for the evolution of tail length in female barn swallows predict that experimental elongation will be costly (see Introduction), as we have found. However, only experimental shortening can distinguish between the two hypotheses. According to the natural selection hypothesis, individuals with shortened tails will suffer a cost because tail length has been displaced from the optimum, what entails flight deficiencies. According to the sexual selection hypothesis, the tail has been elongated by sexual selection beyond the natural selection optimum, and individuals with shortened tails will enjoy a benefit in terms of flight performance, because shortening will bring tail length nearer to that optimum. In this study, as found in previous studies (Cuervo et al., 1996a,b), females with shortened or unmanipulated tails showed no significant differences in a number of variables. This result does not support any of the hypotheses. The nonsignificant effect of experimental tail shortening could be explained in at least two ways. First, we recognize that the number of females involved in the experiment is rather small, and very strong effects would be necessary to show significant differences. A total of 48 females were initially included in the experiment, but only 25 survived to the following year and bred, which implies less than 10 individuals per experimental treatment. With such a small sample size, nonsignificance does not necessarily imply no treatment effect (e.g., nestling comparison between females with shortened and unmanipulated tails, power = 0.07, w = 0.09 [small effect size sensu, Cohen, 1988], although tail length comparison between the same two groups of females, power = 0.24, w = 0.30 [intermediate effect size sensu, Cohen, 1988]). We recognize that conclusions based on such a small sample size should be considered with caution. Second, recent studies have suggested that tail length both in male and female barn swallows might be 10–12 mm longer than the natural selection optimum owing to sexual selection (Buchanan and Evans, 2000; Rowe et al., 2001). If this is correct, our experimental shortening by 20 mm would have resulted in tails 8–10 mm shorter than the natural selection optimum. On the other hand, unmanipulated birds would have tails 10–12 mm longer than the optimum. With such a similar difference in tail length for the two groups of females in relation to the optimal tail length, a similar effect of the two treatments would not be surprising. Interestingly, in a study in which male tail length was manipulated in a similar manner and fitness components were examined the following year, tail lengthening had strong effects on male fitness, but no significant differences were found between males with shortened and unmanipulated tails (Møller, 1989). Effects of tail elongation and shortening for males were quite similar to the effects that we have found for females.

A major result of our study is the negative relationship between male tail length and the future reproductive success of their mates. It is known that female barn swallows adjust their reproductive effort to the attractiveness of their mates. Females mated to long-tailed males, i.e., attractive males, increase their parental investment (de Lope and Møller, 1993). Another nonexclusive explanation could be that long tails impair flight performance, and long-tailed males cannot obtain the same quantity or quality of food (Møller et al., 1995). In that case, females would have to compensate deficiencies of their mates in provisioning of young. However, such compensation does not explain why females mated to attractive males also more often produce a second clutch, than do females mated to short-tailed males, and thereby repeat their differential parental investment (de Lope and Møller, 1993). Differential female investment in reproduction will lead to deterioration in condition. Extra reproductive costs 1 year will be paid for the following year with a decrease in reproductive success. This tradeoff between the allocation of resources to current or future reproductive effort is a cornerstone of life-history theory (Höglund and Sheldon, 1998; Reznick et al., 2000). In general, the findings of this study emphasize the need for long-term studies (the closer to the lifetime of the organism, the better) when attempting to elucidate the effect of a handicap on parental investment. Apparently, absent short-term effects may be owing to compensation for the detrimental effects of handicaps, but it does not imply that they are not important in terms of survival or lifetime reproductive success. Therefore, short-term studies may provide misleading conclusions.

To sum up, in this study we have found a long-term detrimental effect of experimental tail elongation in female barn swallows. Females with elongated external rectrices produced less offspring during the breeding season the following year than did females with shortened or unmanipulated tails. This result suggests that tail elongation caused flight deficiencies that affected condition and eventually reduced reproductive success. The finding of long-term effects but no significant short-term effects (Cuervo et al., 1996a,b) for female tail elongation suggests that female barn swallows have the ability to adjust parental investment. Detrimental effects of long tails in females in terms of low reproductive success might explain why females have shorter tails than do males in this species. Finally, females mated to long-tailed males decreased their reproductive success the following year, possibly owing to differential parental investment that caused deterioration in female condition.

ACKNOWLEDGEMENTS

J.J.C. was supported by a postdoctoral grant from the European Union (Human Capital and Mobility Program) and by Spanish Ministry of Science and Technology (BOS2001-1717), and F.d.L. by grants from the Spanish Ministry of Science and Technology (BOS2000-0293) and Junta de Extremadura (IPR00A021).

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Add comment November 21st, 2007

Cave swallow (Petrochelidon fulva) nest reuse in east-central Texas

repositories.tdl.org
Although nest reuse is most commonly associated with costs such as nest instability and increased ectoparasite loads,contrary evidence supports the possibility that nest reuse might provide an adaptive function in the form of time and energy savings.

The Cave Swallow (Petrochelidon fulva), which nests under bridges and culverts in east-central Texas, chooses predominately to reuse nests when old nests are available. I conducted a field experiment involving bridge pairs and single bridges, in which I applied a treatment of nest removal to one bridge of each pair and one half of each single bridge in order to test whether control bridges and nests exhibited increased productivity from the availability of old nests. I found that a higher percentage of young fledged from control bridges and more fledged per clutch from control bridges. Small sample sizes diminished the ability to detect differences within the single bridge experiment. Results from this research support the time-energy savings concept and may be reconciled with conflicting research through fundamental differences between studies in immunity to ectoparasites, infestation type, and nest microclimate.

Add comment November 19th, 2007

BI Tertarik Kembangkan Sarang Burung Walet di Manado

sinarharapan.co.id/berita
Manado-Bank Indonesia (BI) Manado tertarik mengembangkan sarang burung walet. Tujuannya agar ke depan sarang burung wallet bisa menjadi komoditas andalan daerah Sulawesi Utara (Sulut), karena nilai ekonomisnya yang sangat tinggi.

Pemimpin BI Manado Joko Wardoyo, Sabtu (26/8), mengatakan, keterlibatan BI dalam pengembangan sarang burung walet tersebut diarahkan bagi pengembangan sumber daya manusia (SDM) pengolah produk tersebut. “Proses mendapatkan sarang burung walet masih dilaksanakan dengan metode sederhana, dan BI ingin memberdayakan para petani pengelola sarang burung walet agar dapat menggunakan teknologi lebih maju,” kata Joko.
Dengan teknologi sederhana, selain membutuhkan waktu cukup lama, yakni bertahun-tahun untuk menghasilkan sarang burung walet, jumlah produksinya relatif sedikit. Oleh karena itu, ada masukan dari salah seorang pengusaha walet yang tahu bagaimana mengembangkannya dengan cara modern.
Selain melalui cara budi daya sarang burung tersebut, BI juga ingin melakukan pemberdayaan kepada pengusaha, terutama dalam hal pemasarannya. Upaya itu dilakukan melalui pelatihan dan workshop yang diharapkan akan memberikan tambahan pengetahuan kepada pengusaha mengenai masalah marketing.
Ia mengakui, tingkat risiko budi daya sarang burung walet sangat tinggi, karena meskipun sudah membuat wadah, bisa saja burung walet tidak hinggap di dalamnya, sehingga tidak membentuk sarang. (ant/kbn)

Add comment November 16th, 2007

Swallow Flocks and World Cup Airport Try Coexistence

Environment News Service - Nov 13, 2007
URBAN, South Africa, November 12, 2007 (ENS) - This year, as five million barn swallows migrate from across Europe to roost in South Africa’s Mt. Moreland Reedbed, they will be greeted by air traffic controllers. The controllers will be waiting to warn pilots of the swallow flocks coming in to land so that bird-plane collisions can be avoided.

The plan to protect the birds was announced Monday at a ceremony at the reedbed, attended by the nonprofit conservation group BirdLife South Africa.

The decision to protect the swallows was made in response to global outcry last November, when BirdLife outlined its concern about the expansion of La Mercy Airport at Durban, in preparation for South Africa’s hosting of World Cup 2010.

The airport is being expanded to handle traffic expected for the soccer event and the KwaZulu Natal government wants to see the project completed by 2009.

The Airports Company of South Africa, which administers the existing Durban International Airport, owns the La Mercy land where the $8 billion King Shaka International Airport is under construction, 30 kilometers (20 miles) north of Durban.

The new airport is expected to replace Durban International, which will be decommissioned. But for the swallows at the Mt. Moreland Reedbed, without special planning and accomodation, the airport would have been deadly.

Both the reed bed and Mount Moreland are situated South West of the proposed development are aligned exactly with the proposed runway and so are in the flight patch of aircraft leaving or arriving the airport.

The controllers at La Mercy Airport have been among those watching the millions of birds come in this year from all over eastern and western Europe. They will leave again at the onset of winter.

Add comment November 15th, 2007