Archive for June, 2006
wild-bird-watching.com
The Tree Swallow leaves its wintering grounds along the seacoast from the Carolinas to California to begin its season of mating and nesting habits.
Description
Tree Swallows are 5 to 6 inches long. The Male has iridescent blue upperparts and bright white underparts. In fall, the upperparts may appear greenish. The female has duller, brownish upperparts and grayish underparts.
The female has an immature plumage in the 1st year (sometimes 2nd year). This allows her to approach breeding adult birds and their nest without being chased from the pairs nesting site.
If anything happens to the breeding female and she dies, the younger female bird can replace her.
This helps ensure a successful breeding season.
Mating Habits
Soon after arriving on their breeding grounds in mid March to mid April courtship begins. The birds perch near their nest holes or on top of nesting boxes. Flutter-flight and bowing displays from the male are done in front of the females.
Ocassionally one may see these birds billing. This is the pratice of a mating pair touching bills with one another. Actual mating occurs about a week before egg-laying begins.
Nesting Habits
Tree Swallows prefer open areas near water or in dead trees at the waters edge for nesting.
This bird is a cavity nester and is an ideal candidate for man-made bluebird bird houses. Competition from House Wrens and House Sparrows makes it even more important to place and monitor bird houses for these graceful flyers.
These birds defend only the nest itself. If predators or human visitors approach the nest while the birds are around, the birds may swoop down toward the intruder, turning at the last minute just narrowly missing the intruder. The nest is built primarily by the female, although the male does some gathering of materials. Cup shaped and made of grasses for a foundation and lined with feathers.
The nest building process can take as long as a month but generally completed in 2 to 3 weeks
The female lays 4 to 7 white eggs which are incubated for 13 to 16 days. Sometimes, during egg laying and even incubation time, the nest may be abandoned for a few days.
During this time you’ll see no activity around the nesting site. Within 3 - 4 days the birds return.
This leave-of-absence apparently has no effect on the success of the young birds hatching, only delaying the event.
The female performs the job of incubation and both parents feed the young. The young birds will leave the nest in 16 - 24 days after hatching.
1 - 2 broods each season.
Feeding Habits
The diet of the these birds consist mainly of insects caught on the wing. In winter bayberries are a favorite food. By late July or early August the Swallows leave their breeding grounds and form flocks around marshy areas where there are plenty of flying insects.
In early fall the Tree Swallows will begin migrating southward. In winter they feed in large flocks until early spring migrating back in much smaller flocks.
June 23rd, 2006
enature.nationalgeographic.com
Cliff Swallows are colonial — that is, they nest in colonies, sometimes numbering in the thousands of birds. In many ways the members of a colony appear to display remarkable social cohesiveness. They work together to mob predators and will even learn from each other where the good food sources are. But if you look closely at a Cliff Swallow colony, you’ll see that this seemingly cooperative community also harbors its share of dastardly misbehavior.
In every colony there are a few swallows (you might call them bad eggs) that parasitize their neighbors. They do this not by sucking other swallows’ blood or stealing food, but by putting their eggs in nests other than their own. Sometimes the sneaky swallow will even toss out one of the nest owner’s eggs before laying her egg in its place! This behavior is known as brood parasitism. The extra eggs go undetected, and the surrogate parents end up doing the work of raising the slacker’s young.
These parasitic egg-laying visits are clandestine and quick, but some Cliff Swallows have been spotted launching an even faster, more remarkable sneak attack: carrying eggs in their very small beaks (adapted for catching tiny insects on the wing) and quickly dropping them into a neighbor’s nest. Incoming!
Cliff Swallow Petrochelidon pyrrhonota (Hirundo pyrrhonota
Family: Hirundinidae, Swallows view all from this family
Description 5-6″ (13-15 cm). Sparrow-sized. A stocky, square-tailed swallow with pale buff rump. Upperparts dull steel-blue; underparts buff-white; throat dark chestnut; forehead white. Southwestern birds have chestnut foreheads. Cave Swallow of Texas and Southwest is similar but smaller, with darker rump and pale buff throat.
Habitat Open country near buildings or cliffs; lakeshores and marshes on migration.
Nesting 4-6 white eggs in a gourd-shaped structure of mud lined with feathers and placed on a sheltered cliff face or under eaves. Nests in colonies.
Range Breeds from Alaska, Ontario, and Nova Scotia southward through most of United States except Southeast. Winters in tropics.
Voice   Constant squeaky chattering and twittering.
Discussion As its name implies, this swallow originally nested on cliffs. The introduction of House Sparrows was a disaster for these birds, since the sparrows usurp their nests and often cause the swallows to abandon a colony. Long, cold, rainy spells while the young are in the nest also cause widespread mortality since the adults are unable to obtain enough insects. In California they often return in early spring to ancestral colonial breeding sites. If it turns chilly, however, they will abandon the area until weather and feeding patterns are more favorable, and return “on schedule” for their publicized arrival on March 19 at Mission San Juan Capistrano.
June 23rd, 2006
beheco.oxfordjournals.org
Anders Pape Møller
Laboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie, Bât. A, 7ème étage, 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France
Address correspondence to A.P. Møller. E-mail: amoller@snv.jussieu.fr.
Among bird species in which males contribute to nest building, sexual selection has favored larger nests. I investigated determinants of nest size in the barn swallow Hirundo rustica and how nest size changed during the period 1977–2003, when tail length (a male secondary sexual character) increased by more than 1.2 standard deviations. Males with short tails contributed more to nest building than long-tailed males, signaling their future investment in food provisioning of offspring. Pairs of barn swallows were consistent in nest size when build ing new nests the same or different years, and level of phenotypic plasticity in nest size was small and could not account for temporal patterns in nest size. Offspring resembled their parents with respect to nest size, indicating a significant heritability of nest size, independent of whether offspring were reared by their parents or by foster parents, and there was a significant negative genetic correlation between male tail length and outer nest volume and amount of nest material. The temporal increase in male tail length was associated with a decrease in nest size, with the amount of nest material in 2003 on average being less than a third of the amount used in 1977. Temporal change in nest size could be accounted for by indirect selection on tail length causing change in nest size to match that predicted from change in tail length and the genetic correlation between male tail length and nest size.
Key words: barn swallow, heritability, Hirundo rustica, nest building, parental care.
June 23rd, 2006
merlejacobs.com
Møller (1) found that experimental lengthening the tail of barn swallow males led to earlier mating and therefore an increase in offspring. Since he observed no significant differences in intensity of male-male aggressive encounters among males at the nesting sites he attributed the early mating solely to female choice. This released a flood of anthropomorphic speculations on what the female has in mind when she chooses a mate.
However, the earlier mating might be merely the result of use of the elongated tail as a status symbol in competition for foraging territories (100-500m from the nesting sites). Such use of display features would save energy otherwise used in physical fighting and competitive racing. The same could be said for the white spots on top of the tail as positively related to elongation of the tail. White spots are commonly displayed by birds in competition for food reserves.
Møller (2) does indeed carefully describe competitive flights of barn swallows in groups from which females are attracted to the nesting territories, though Møller does not consider any possible relationship between the area of such flights and reproductive resources. Such a relationship is clearly evident with the dragonfly, Perithemis tenera, in which groups of males perform competitive flights in areas from which females are later attracted (3). This resembles “trysting” behavior commonly observed among insects.
The male white-tailed skimmer dragonfliy, Plathemis lydia, displays the white upper surface of the abdomen toward other males competing for reproductive resources. Artificial blackening of the white surface diminishes territorial success of the males. This experimental elimination of the white feature results in greater expenditure of energy on the part of the blackened males (3). Observation would reveal the more successful in competition among these males (the white ones) would show less competitive intensity than the less successful (the black ones).
Among the barn swallows, optimal territory with plentiful food may influence the female in choice of a mate. Under natural conditions, Syrphidae flies form an important fraction of the food (2). These weak-flying yellowish flies that hover and perch on flowers may determine survival of the first brood of swallows in the cold spring weather. This may well account for the earlier mating and reproductive success of the males with the elongated tails. Regarding male features that attract females at the nesting sites, candidates might be the bright yellow gaping billl set off by the surrounding reddish plumage. The male displays these features toward the female at the nest site. The resplendency of the plumage may be conditioned by the adequate nutrition the competitively advantaged male has received in his foraging territory near the end of his prenuptial molt.
1. A.P. Møller (1992). Nature 357, 238-240,
2. A.P. Møller (1994). Sexual Selection and the Barn Swallow. Oxford University Press.
3. M.E. Jacobs (1955). Ecology 36, 566-586.
June 22nd, 2006
By Tanya Dewey
Information
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves
Order: Passeriformes
Family: Hirundinidae
Genus: Hirundo
Species: Hirun
Barn swallows are native in all the biogeographic regions except Australia and Antarctica. The breeding range of barn swallows includes North America, northern Europe, northcentral Asia, northern Africa, the Middle East, southern China, and Japan. They winter in South America, South Asia, Indonesia, and Micronesia. (Terres, 1980)
Biogeographic Regions:
nearctic (native ); palearctic (native ); oriental (native ); neotropical (native ).
Other Geographic Terms:
holarctic .
Reproduction
Barn swallows are socially monogamous. However, extra-pair copulations are common, making this species genetically polygamous. Breeding pairs form each spring after arrival on the breeding grounds. Pairs re-form each spring, though pairs that have nested together successfully may mate together for several years. Males try to attract females by spreading their tails to display them and singing.
Several studies have researched sexual selection in barn swallows. Moller (1994) documented female barn swallows selecting for symmetrical wings and tails in potential mates. Males exhibiting greater symmetry acquired mates more quickly than did asymmetric males. Asymmetry can result from genetic factors such as inbreeding or mutations as well as from environmental stress such as food deficiency, parasite infestation, or the presence of pathogens. Moller observed that individuals affected by these factors not only exhibited asymmetry, but also decreased strength and longevity. Therefor, females that selected symmetrical mates would presumably be selecting superior mates. In addition to selecting for symmetry, females also tend to select males with longer tail feathers. Moller observed a connection between the tail length of male barn swallows and their offspring’s vitality and longevity. Males with longer tail feathers exhibit traits of greater longevity which is passed on to their offspring. Females thus gain an indirect fitness benefit from this form of selection, as longer tail feathers indicate a genetically stronger individual who will produce offspring with enhanced vitality. Individuals with longer tails have also been observed to demonstrate greater disease resistance than their short-tailed counterparts. There is also evidence that males select female mates with long tails.
Unmated adults often associate with a breeding pair for up to an entire season. Though these “helpers” do not usually feed the young, they may help with nest defense, nest building, incubation and brooding. “Helpers” are predominantly male, and may succeed in mating with the resident female, leading to polygyny. (Bolzern, Moller, and Saino, 1997; Brown and Brown, 1999; De Lope and Moller, 1993; Moller, 1993; Moller, 1994a; Moller, 1994b)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
In North America, both barn swallow parents incubate the eggs and feed the nestlings. However, females provide more parental care than do males. During the nestling period, barn swallow parents may feed their nestlings up to 400 times per day. Barn swallows feed their chicks insects compressed into a pellet, which is transported to the nest in the parent’s throat. Although all swallows are socially monogamous, barn swallows differ from most swallow species in the sharing of parental care. Juveniles from the first brood of the season have even been observed assisting their parents in feeding a second brood. (Perrins, 1989; Terres, 1980)
Parental investment:
altricial ; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (protecting: male, female); pre-weaning/fledging (provisioning: male, female, protecting: male, female); pre-independence (provisioning: male, female, protecting: male, female); post-independence association with parents.
Lifespan/Longevity
The average lifespan of barn swallows is 4 years. Barn swallows of 8 years of age have been documented, but these are considered the exception. Survival prospects and longevity appear to increase with tail length and wing and tail symmetry. (Moller, 1994a; Moller, 1994b; Perrins, 1989; Terres, 1980)
Behavior
Barn swallows are diurnal and migratory. They have individual songs and often sing as a chorus.
Barn swallows are often seen in large social groups sitting on telephone wires or other elevated structures. They also nest colonially, probably as a result of the distribution of high quality nest sites. Within a colony, barn swallows defend a territory around their nest. In European barn swallows, these territories range in size from about 4 to 8 square meters. (Hebblethwaite and Shields, 1990; Moller, 1991)
A study in West Virginia found that barn swallows foraged within 1.2 km of their nests. In Europe, barn swallows foraged within 500 m of their nest. (Brown and Brown, 1999)
Key behaviors:
troglophilic; flies; diurnal ; motile ; migratory ; territorial ; colonial .
Communication and Perception
Barn swallows use vocalizations and body language (postures and movements) to communicate. Barn swallows sing, both individually and as a group. They have a wide variety of calls used in different situations, from predator alarm calls, to courtship calls, and calls of young in nests. Nestlings give off a faint chirp while begging for food. Barn swallows also make clicking noises, which they create by snapping their jaws together. (Brown and Brown, 1999)
Communicates with:
visual ; acoustic .
Other communication keywords:
choruses .
Perception channels:
visual ; tactile ; acoustic ; chemical .
Food Habits
Barn swallows are insectivores. Flies < >, grasshoppers, crickets, dragonflies, beetles, moths and other flying insects make up 99 % of their diet. They catch most of their prey while in flight, and are able to feed their young at the nest while flying.
Barn swallows forage opportunistically. They have been observed following tractors and plows, catching the insects that are disturbed by the machinery. They drink water by skimming the surface of a body of water while flying. (Brown and Brown, 1999; Perrins, 1989; Terres, 1980)
Primary Diet:
carnivore (insectivore ).
Animal Foods:
insects.
Predation
American kestrels and other hawks, such as sharp-shinned hawks and Cooper’s hawks, eastern screech owls, gulls, common grackles, boat-tailed grackles, rats, squirrels, weasels, raccoons, bobcats, domestic cats, snakes, bullfrogs, fish and fire ants are predators of barn swallows. Barn swallows usually give alarm calls when predators come near. Most predators of barn swallows attack the nestlings, but hawks, falcons, and owls tend to hunt adults.
Barn swallows mainly escape predators by being swift and agile in flight and by building their nests in places that are difficult for predators to reach. (Barker, Ewins, and Miller, 1994; Brown and Brown, 1999)
Ecosystem Roles
Although incidents of cowbirds parasitizing barn swallow nests are rare, they have been documented. A 1994 observation of 67 Barn Swallow nests found two of these nests to contain cowbird eggs, which were laid by the parent cowbird and left in the barn swallow nest in a parasitic fashion for the barn swallows to raise. Each of these nests contained 1 cowbird egg and both eggs were incubated by the barn swallows along with their own eggs. However, only one of the cowbird eggs hatched. The single cowbird hatchling fledged normally, thus demonstrating that barn swallows are capable of acting as cowbird hosts.
Barn swallows frequently engage in a symbiotic relationship with ospreys, coexisting in a single nesting area to the mutual benefit of both species. Barn swallows will nest either below a much larger osprey nest or in a portion of an abandoned osprey nest. By nesting near an osprey population, the barn swallows receive protection from birds of prey, which are driven away from the nests by the much larger ospreys. In return, ospreys are alerted to the presence of these predators by the barn swallows which give alarm calls when predators are nearby.
Barn swallows eat an enormous amount of insects and are very important in the control of their populations. Barn swallows are also a useful food source for many predators. (Barker, Ewins, and Miller, 1994; Brown and Brown, 1999; Wolfe, 1994)
Species (or larger taxonomic groups) that are mutualists with this species
• Ospreys
Economic Importance for Humans: Negative
Some humans feel that barn swallow nests are a nuisance, and are unsightly when they are attached to buildings and other man-made structures. Large colonies in urban areas can also create detrimental cleanliness and health issues for humans. Finally, salmonella can be transmitted through their feces, posing a threat to livestock that live in close proximity to barn swallow colonies. (Brown and Brown, 1999; Perrins, 1989)
Ways that these animals might be a problem for humans:
causes or carries domestic animal disease .
Economic Importance for Humans: Positive
Barn swallows are quite effective in reducing insect pest populations. They also can serve as an indicator or trigger organism, indicating possible environmental trouble, as declines in their relatively abundant numbers may precede other more obvious effects of environmental stress. (Moore, 2001; Perrins, 1989)
Ways that people benefit from these animals:
controls pest population.
Conservation Status
Barn swallow populations are generally considered to be stable and sufficiently extensive. However, declines in the amount of acreage devoted to agriculture in recent years have resulted in reduced barn swallow numbers. This can be attributed to a reduction in habitat as the barns and outbuildings which once housed barn swallows, give way to more urban settings. Another contributing factor is the reduction in food supply. Insects attracted by the presence of livestock and the ideal surrounding habitat are the primary food source for barn swallows living in agricultural areas. Locations where farming has ceased exhibit a 50% reduction in insect populations.
Barn swallows continue to be widespread and common throughout their range. There are an estimated 190,000,000 individuals worldwide. (Brown and Brown, 1999; Moore, 2001)
Contributors
Tanya Dewey (author), Animal Diversity Web, University of Michigan Museum of Zoology.
Chava Roth (author), Western Maryland College.
Randall L. Morrison (editor), Western Maryland College.
Kari Kirschbaum (editor), Animal Diversity Web Staff.
References
Barker, E., P. Ewins, J. Miller. 1994. Birds breeding in or beneath Osprey nests. Wilson Bulletin, 106: 743-750.
Beecher, M., M. Medvin, P. Stoddard. 1993. Signals for parent-offspring recognition: a comparative analysis of the begging calls of Cliff Swallows and Barn Swallows. Animal Behavior, 45: 841-850.
Bolzern, A., A. Moller, N. Saino. 1997. Immunocompetence, ornamentation, and viability of male Barn Swallows. Proceedings of the National Academy of Sciences, 94: 54-552.
Brown, C., B. Brown. 1999. Barn swallow (Hirundo rustica). Pp. 1-32 in A. Poole, F. Gill, eds. The Birds of North America, Vol. 452. Philadelphia, PA: The Birds of North America.
De Lope, F., A. Moller. 1993. Female reproductive effort depends on the degree of ornamentation. Evolution, 47: 1152-1161.
Hebblethwaite, M., W. Shields. 1990. Social influences on Barn Swallow foraging in the Adirondacks: a test of competing hypotheses. Animal Behavior, 39: 97-104.
McWilliams, G. 2000. The Birds of Pennsylvania. New York: Cornell University Press.
Moller, A. 1991. The preening activity of swallows, *Hirundo rustica*, in relation to experementally manipulated loads of haematophagous mites. Animal Behavior, 42: 251-260.
Moller, A. 1993. Sexual selection in the Barn Swallow *Hirundo rustica*: female tail ornaments. Evolution, 47: 417-432.
Moller, A. 1994. Male ornament size as a reliable cue to enhanced offspring viability. Proceedings of the National Academy of Sciences, 91: 6929-6932.
Moller, A. 1994. Patterns of fluctuating asymmetry and selection against asymmetry. Evolution, 48: 658-671.
Moore, P. 2001. Dairy declines hard to swallow. Nature, 411: 904-905.
Perrins, C. 1989. Encyclopedia of Birds. England: Equinox Ltd..
Terres, J. 1980. The Audubon Society Encyclopedia of North American Birds. New York: Alfred A. Knopf, Inc.
Wolfe, D. 1994. Brown-headed Cowbirds fledged from Barn Swallow and American Robin nests. Wilson Bulletin, 106: 764-767.
June 22nd, 2006
sfgate.com
Rob Lee
Whether the Giants are winning games in big fistfuls, or can’t produce as much offense as a foul-mouthed grandmother, there’s always a good reason to go to their ballpark. I’m not talking about the starlings foraging in the outfield grass, or the hordes of Western gulls that begin gathering faithfully during the seventh-inning stretch (although the best seats for my proposed entertainment are in the upper deck, with the gulls).
I’m speaking of the barn swallow and the white-throated swift, foraging on all those beer-crazed bugs rising off the crowd. While these birds are seemingly quite similar — long, swept-back wings, the aerodynamics of great fliers — the swallow is a song bird and the swift is not; actually more closely related to hummingbirds.
Sitting high in this bird observation platform, formerly known as the Giants’ home, you’ll notice that the two birds have different flying techniques. The swallow cuts a graceful, complicated swath through the air, constantly maneuvering to pick off one insect after another, while the swift is just that; flashing under the stadium lights like a jet, using a few quick, powerful strokes of its wings and then a short glide, eating the tiny insects — “aerial plankton” — in its path.
The white-throated swift may be the fastest bird in North America, once estimated to have fled a swooping falcon at more than 200 mph. It could easily keep pace with, inspect and then pass a soaring Barry Bonds homer. Both of these birds have wings “built for speed,” but the swallow has slender, flexible wing bones suitable for its elegant flight, while the swift has shorter, more massive bones (and long primary feathers), with which it can achieve the stiff, superfast wing beats that give it surpassing speed.
Swallows typically fly lower to the ground, pursuing insects (their hard work providing a very nutritious diet), while swifts fly high, on a line, and much longer distances, hunting for clouds of anthropoids to charge through repeatedly. While the swift’s flight uses less energy, it also yields less nutrition in the types of insects caught. (Swifts typically fly more than 500 miles a day, and, as they are long-lived for small birds — larger swifts may live more than 20 years — well over a million miles in their lifetime.)
Both birds do nearly everything in flight, including drinking, bathing, courting, and, among swifts, copulating. Some swifts, after mounting high in the sky, are even thought to sleep in flight.
Flying is so central to the lives of these birds that the swallow can only walk with difficulty and the swift can’t walk at all. Swallows have tiny, weak legs and feet that only allow perching on such things as wires or thin twigs. Swifts’ legs are virtually nonexistent, but they have tiny, strongly clawed feet, all four toes facing forward, with which they can hang on vertical surfaces, such as cliffs or buildings.
Barn swallows are a really lovely bird, artistically colored in blue, rust and buff with a long swallowtail, while the swift is basic black and white.
Barn swallows raise four to five chicks in their mud-and-grass cup nest, usually affixed under the eaves of a building or beneath a bridge. (These swallows have used human structures for nesting so widely, and for so long, their natural sites are virtually forgotten.) White-throated swifts raise a similar brood in very inaccessible crevices in cliffs, and sometimes buildings. Gathering twigs on the wing from dead trees, they build a cup nest, which they cement in place, and together, with saliva.
The close proximity to people with which these swallows consistently nest makes them one of the easiest nesting birds to observe, while this swift is just the opposite, with relatively little known about its nesting behaviors.
Both birds migrate, but the white-throated swift doesn’t go very far, usually not beyond the Southwest. The barn swallow is a champion long-distance migrator, some birds going 7,000 miles each way. Both of these species are social, usually found in small to large flocks, although the individuals I saw at the ballpark were alone.
I can’t promise the birds will show up when you go to a game, but if they do, it will be a joy to watch their two styles of mastery above the crowd, the two species, in a way, mirroring the combination of relaxation and intensity that characterizes baseball.
June 21st, 2006
oas.ucok.edu
Eric Whelan
Abstract
Barn swallows, Hirundo rustica, are small migratory birds found almost anywhere. They stay in Oklahoma for nine months at a time and migrate to the south. They have two broods a breeding season. Their nests are made of soil, plants and other materials available to them. The objectives of my research were to find whether there was a positive correlation between mass in grams and percentage of organic matter, to find whether there was a positive correlation between diameter and percentage of organic matter. I collected the nests under the eaves of McLoud High School’s West building. The nest did not come down easily and many broke during collection. The nests were sorted for organic and other materials. They were mixed well in water and settled into distinct layers- sand, clay, and silt. They were classified into soil types. My hypothesis is that the mass in grams has a positive correlation with the percentage of organic matter, and the diameter has a positive correlation with the percentage of organic matter. My initial hypothesis was contradicted by the data collected. Neither showed any correlation.
Introduction
Barn swallows, Hirundo rustica, are small migratory birds that live in every continent except Antarctica and Australia. They spend mid January to September in Oklahoma. They spend winters in the Southern United States and Mexico.
Barn swallows have one to two broods every breeding season. The first brood of the season helps the parents care for the second brood of the season. They return and rebuild their nest every breeding season. The nest is primarily made of soil and plants and is built under bridges, eaves of buildings, and barns as the name implies. (1)
This summer I had the opportunity to attend Field Studies of Multidisciplinary Biology at the University of Oklahoma Biological Station. I developed an interest toward the animal kingdom (especially birds) and plant kingdom (especially grasses). Thus the objective of this project was to learn about the natural history of barn swallows by investigating the contents of the nest in terms of plants and animals that compose the nests. I also wanted to learn about the inorganic composition by classifying the soil type. I wanted to relate the size and mass of the nest in terms of percentage of organic material to size and mass to see if there is a positive correlation between size and percentage organic material and a positive correlation between mass and percentage of organic matter.
Methods and Materials
The nests were collected under the eaves of McLoud High School’s West building. They were cut down using a dissecting scalpel and placed in two paper bags. One bag for the north side of the building and one bag for the south side to keep the sides separate. The mass, in grams, of each nest was taken. The diameters of the nests were measured in centimeters; some nests were impossible to determine due to breakage during collection. Each nest was then taken apart and sorted for plants, animals, manure, feathers, and other materials. The nest was then placed in a beaker with water and mixed well in order for the remaining organic matter to float to the top and be collected by scraping the surface with a screen. The mixture was allowed to settle into 3 distinct layers-sand, clay, and silt. A soil classification pyramid (see Figure 1) was used to classify the soil. The organic mass was measured. The organic matter was sorted for grass spikelets, reproductive parts, seeds, small animals, feathers, and broad leaves. The organic matter was then identified (2,3,4,5). Dividing the grams of organic matter by the grams of total mass collected the percentage of organic matter was calculated.
Results
Of the 19 nests collected all contained organic matter; however, not all had identifiable features. Table 2 shows the species of plants that were found in each nest. The most common plant species found in the nests was Cynodon dactylon (2). Small acorns were found in nest 4. Small snail shells were found in nests 7 and 14. Parts of a cricket were found in nest 13. Nest 3 contained woodpecker, rock dove and American robin feathers. Nest 19 contained red tail hawk, Paris woodpecker, rock dove, and American robin feathers. No barn swallow feathers were found because barn swallows will not pluck their own feathers for the lining of the nest. Nest 3 contained carpet, tarp, plastic packaging, thread, and dental floss. Nest 7 contained horse hair. Nest 11 contained pieces of carpet. Nest 19 contained twine and cigarette packaging. Table 2 shows the plant species found in the nests, animals found in the nest, and other materials found in the nest. Of the 19 nests collected, 63.4% were soil type loam, 15.8 % were soil type sandy loam, 10.5% were soil type silty loam, and 10.5% were soil type clay loam. Table 1 shows diameter in centimeters, mass in grams, percent organic matter, soil type, number of plant species, number of animal species, and number of other materials.
Discussion of Results
My initial hypothesis that percentage of organic matter had a positive correlation with mass was contradicted. The mass and organic matter shows no correlation, positive or negative. The initial hypothesis that diameter and percentage organic matter had a positive correlation was also contradicted. They show no correlation. Figure 2 shows the correlation between mass in grams and the percentage of organic matter. Figure 3 shows the correlation between diameter in centimeters and percentage organic matter.
Acknowledgements
I would like to thank most of all Dr. Bruce Smith, for helping me tremendously with this project and keeping me on task. I would like to thank Paula Tolbert for always asking what she can do to help, staying hours after school to help and going out of her way to make this project so much easier. I would like to thank Dr. Mike Bay for his contribution to this project. I would also like to thank Jessica Schmidlkofer, Brad Story, Tyler Hill, Miranda Fetters, and Craig Hatfield.
June 21st, 2006
sarep.ucdavis.edu
Article written for Sustainable Agriculture
Chuck Ingels
Farmers and ranchers are looking closely at the benefits barn owls offer as an alternative method of controlling vertebrate pests (see Sustainable Agriculture Vol. 5. No. 1). The diet of the barn owl (Tyto alba) is relatively easy to ascertain, and several dozen studies have been conducted throughout the U.S. to determine the prey species consumed (Clark and Bunck, 1991). Barn owls swallow their prey whole and later regurgitate one to two inch pellets containing undigested bones, teeth, and fur. The owls usually produce one to two pellets per day, often dropping one at their nesting site and one at a distant roosting site (Evans and Emlen, 1947). Skulls found in these pellets can be keyed out to determine the identity of the prey species.
Over 95 percent of the diet usually consists of small mammals (mostly rodents), however in some studies substantial bird remains have been found. According to Colvin (1986), each adult barn owl may consume about one or two rodents per night; a nesting pair and their young can eat over 1,000 rodents per year. Dietary studies from California and other states show that a barn owl consumes an average 50 to 60 grams of prey per day (0.11-0.13 pounds per day, 40-48 pounds per year). The actual species consumed depends on the species abundance and availability in the area.
Overview
Table 1 shows the results of several barn owl prey studies conducted in California. In many studies, meadow voles and/or pocket gophers were consumed most often, while pocket, white-footed, and house mice were also important. One notable species missing in nearly all these studies is the California ground squirrel (Spermophilus beecheyi). This species ventures above ground only during the day, while the barn owl hunts almost strictly at night.
Study Findings
Berkeley 1926-27. Because each of these studies took place in Berkeley and because the results of each were very similar, the percentages of each species were averaged and combined into one column. In one study (Foster, 1926), pellets were collected on one sampling date from under a nest in Wildcat Canyon, just northeast of Berkeley. In another study (Foster, 1927), pellets were collected over a period of one and a half years from a nest located in a cave in Wildcat Canyon. Prey counts were separated by the dry season vs. the wet season. More shrews, Jerusalem crickets, and white-footed and pocket mice were taken during the dry season than the wet season, while the opposite was true for pocket gophers. In a third study (Hall, 1927), accumulated pellets were collected on one sampling date from a location in Berkeley.
San Francisco Bay region (Smith and Hopkins, 1937). In this study, 12 boxes were installed in trees and barns in these counties: Marin (4), Contra Costa (2), Alameda (3), and San Mateo (3). A total of 141 pellets were collected over three years. California meadow voles were found most frequently except in Marin County, where pocket gophers predominated.
Central California (Hawbecker, 1945). Pellets were collected over a wide area during the nesting seasons of several years. Three types of habitat were included in this study, ranging from a well-forested, humid region to one that is treeless and shrubless. The specific regions and important prey findings are as follows:
1. Santa Cruz and western Monterey counties (coastal Transition Zone): pocket gophers-33%, meadow voles-17%, and birds-16%.
2. Eastern Monterey and western San Benito counties (Upper Sonoran zone): pocket gophers-52%, pocket mice-17%.
3. Western Merced and Fresno counties (Lower Sonoran Zone): pocket mice-66%.
Based on rodent trapping in several of the study areas, the barn owl was found to serve as a good sampler of the small mammals of a given area. However, the author noted that the selection of species appeared to be based partially upon numbers and ease of capture.
Davis (Evans and Emlen, 1947). An average of one pellet per day was found beneath a palm tree over a one year period. The palm tree served as a daytime roost to one barn owl. Based on nighttime observations, the owl was determined to have a hunting range of about 165 acres. About 140 acres were in open fields planted largely to grain and alfalfa and 25 were in wooded areas along Putah Creek. Animals typically associated with wooded or brushy cover, including house mice, deer mice (Peromyscus), harvest mice, and roof rats, comprised 57 percent of the total food items. Open field habitats, more than six times as extensive on the owl’s range, contributed the remaining 43 percent of the items, which included pocket gophers and meadow voles. During the fall, the numbers of house and deer mice taken declined, while pocket gopher numbers steadily increased from winter through fall.
Madera County foothills (Fitch, 1947). This study was conducted in the blue oak-Digger pine belt of the Upper Sonoran Zone of Madera County. The region is comprised of rolling foothills broken by numerous ravines, and includes substantial grassland. Barn owl pellets were collected over four years at four sites. Computed on a prey weight basis, the pocket gopher accounted for 71 percent of the diet of the barn owls. Pellets were also collected from day roosts of great horned owls, which were far more numerous than barn owls in this area. The diet of the great horned owls consisted largely of Jerusalem crickets, woodrats, cottontails, kangaroo rats, and pocket gophers. On a weight basis, 56 percent of the diet was cottontails. For comparison, the diet of red-tailed hawks was also presented from a related study. On a weight basis, 50 percent of the diet of the hawks consisted of ground squirrels.
Coastal Los Angeles County (Cunningham, 1960). Pellets were collected once from the base of a date palm tree. Because of the abundance of wood rats and the low percentage of pocket gophers and meadow mice, the author concluded that the barn owls foraged largely in the chaparral-covered Santa Monica Mountains about two miles north of the collection site. Two samples of great homed owl pellets were also taken; their diet consisted mostly of pocket gophers, house mice, meadow mice, and wood rats.
Placer County (Clark and Wise, 1974). Pellets were collected at eight sites along the eastern edge of the Sacramento Valley, mostly from barns just northwest of Lincoln. On a weight basis, over half of the diet of the barn owl consisted of pocket gophers, while white-footed mice accounted for only about seven percent.
Siskiyou County (Rudolph, 1978). This study examined the coexistence and diets of barn owls and great horned owls at Tule Lake National Wildlife Refuge. The owls roosted on rock cliffs with a hunting range that included natural vegetation and agricultural fields. Pellets were collected at weekly intervals from the roosting sites. The diet of the great horned owls was very similar to that of the barn owls. Barn owls were found to hunt primarily on the wing, while great horned owls hunted primarily from telephone poles.
References
Clark, D.R. and C.M. Bunck. 1991. Trends in North American small mammals found in common barn owl dietary studies. Canadian Journal of Zoology 69:3093-3102.
Clark, J.P. and W.A. Wise. 1974. Analysis of barn owl pellets from Placer County, CA. The Murrelet 55(l):S-7.
Colvin, B.A. 1986. Barn owls: Their secrets and habits. Illinois Audubon, No. 216, Spring 1986.
Cunningham, J.D. 1960. Food habits of the horned and barn owls. The Condor 62:222.
Evans, F.C. and Emlen, J.T., Jr. 1947. Ecological notes on the prey selected by a barn owl. The Condor 49:3-9.
Fitch, H.S. 194 7. Predation by owls in the Sierran foothills of California. The Condor 49:137-151.
Foster, G.L. 1927. A note on the dietary habits of the barn owl. The Condor 29:246.
Hall, E.R. 1927. The barn owl in its relation to the rodent population at Berkeley, CA. The Condor 29:274-275.
Hawbecker, A.C. 1945. Food habits of the barn owl. The Condor 47:161-166.
Jameson, E.W., Jr. and H.J. Peeters. 1988. California Mammals. University of California Press, Berkeley, CA.
Rudolph, S.G. 1978. Predation ecology of coexisting great horned and barn owls. The Wilson Bulletin 90(l):134-37.
Smith, C.E and C.L. Hopkins. 1937. Notes on the barn owls of the San Francisco Bay region. The Condor 39:189-191.
For more information write to: Chuck Ingels, UC SAREP, University of California, Davis, CA 95616.
(CI-PEST.137) Contributed by Chuck lngels
June 20th, 2006
.theava.com
by Rob Lee
Whether the Giants are winning games in big fistfuls, or can’t produce as much offense as a foul-mouthed grandmother, there’s always a good reason to go to their ballpark. I’m not talking about the starlings foraging in the outfield grass, or the hordes of Western gulls that begin gathering faithfully during the seventh-inning stretch (although the best seats for my proposed entertainment are in the upper deck, with the gulls).
I’m speaking of the barn swallow and the white-throated swift, foraging on all those beer-crazed bugs rising off the crowd. While these birds are seemingly quite similar — long, swept-back wings, the aerodynamics of great fliers — the swallow is a song bird and the swift is not; actually more closely related to hummingbirds.
Sitting high in this bird observation platform, formerly known as the Giants’ home, you’ll notice that the two birds have different flying techniques. The swallow cuts a graceful, complicated swath through the air, constantly maneuvering to pick off one insect after another, while the swift is just that; flashing under the stadium lights like a jet, using a few quick, powerful strokes of its wings and then a short glide, eating the tiny insects — “aerial plankton” — in its path.
The white-throated swift may be the fastest bird in North America, once estimated to have fled a swooping falcon at more than 200 mph. It could easily keep pace with, inspect and then pass a soaring Barry Bonds homer. Both of these birds have wings “built for speed,” but the swallow has slender, flexible wing bones suitable for its elegant flight, while the swift has shorter, more massive bones (and long primary feathers), with which it can achieve the stiff, superfast wing beats that give it surpassing speed.
Swallows typically fly lower to the ground, pursuing insects (their hard work providing a very nutritious diet), while swifts fly high, on a line, and much longer distances, hunting for clouds of anthropoids to charge through repeatedly. While the swift’s flight uses less energy, it also yields less nutrition in the types of insects caught. (Swifts typically fly more than 500 miles a day, and, as they are long-lived for small birds — larger swifts may live more than 20 years — well over a million miles in their lifetime.)
Both birds do nearly everything in flight, including drinking, bathing, courting, and, among swifts, copulating. Some swifts, after mounting high in the sky, are even thought to sleep in flight.
Flying is so central to the lives of these birds that the swallow can only walk with difficulty and the swift can’t walk at all. Swallows have tiny, weak legs and feet that only allow perching on such things as wires or thin twigs. Swifts’ legs are virtually nonexistent, but they have tiny, strongly clawed feet, all four toes facing forward, with which they can hang on vertical surfaces, such as cliffs or buildings.
Barn swallows are a really lovely bird, artistically colored in blue, rust and buff with a long swallowtail, while the swift is basic black and white.
Barn swallows raise four to five chicks in their mud-and-grass cup nest, usually affixed under the eaves of a building or beneath a bridge. (These swallows have used human structures for nesting so widely, and for so long, their natural sites are virtually forgotten.) White-throated swifts raise a similar brood in very inaccessible crevices in cliffs, and sometimes buildings. Gathering twigs on the wing from dead trees, they build a cup nest, which they cement in place, and together, with saliva.
The close proximity to people with which these swallows consistently nest makes them one of the easiest nesting birds to observe, while this swift is just the opposite, with relatively little known about its nesting behaviors.
Both birds migrate, but the white-throated swift doesn’t go very far, usually not beyond the Southwest. The barn swallow is a champion long-distance migrator, some birds going 7,000 miles each way. Both of these species are social, usually found in small to large flocks, although the individuals I saw at the ballpark were alone.
I can’t promise the birds will show up when you go to a game, but if they do, it will be a joy to watch their two styles of mastery above the crowd, the two species, in a way, mirroring the combination of relaxation and intensity that characterizes baseball.
June 20th, 2006
Peterborough, N.H.
mledger.com
A Column By Francie Von Mertens
The tide has turned. It turns slowly, and then really gets going. Mid-May brings the biggest surge of birds — a combination of species that nest locally as well as some passing through to nesting grounds farther north.
I’ve kept a birding calendar for 10 years now, and this time of year each day gets an entry. Today’s came late, in the sunset hour.
Overhead, elegant as always in flight, its rust-colored front accentuated by a sunset glow, a backyard favorite made its first appearance of the year. I checked to make sure both barn door and hayloft door were opened wide and welcoming.
Barn Swallows arrive in late April with the same general punctuality as other migrants — sometimes arriving the same day as previous years; sometimes within the week.
The Barn Swallow high overhead had Tree Swallows for company, their fronts showing white and their tales squared rather than swallow-tailed. It took a search with binoculars to finally find a companion Barn, and then, in time, a third among the majority Trees.
They were foraging high. As light faded, I wondered where they would spend the night when two swallows swept lower and lower. For the first time since last Aug. 28, our barn will host Barn Swallows for the night.
Aristotle is quoted as saying, “One swallow does not make a summer.” The day the first Barn Swallows returned to our barn was a glorious summer day, but we all know there’s more cold to come. One glorious, T-shirt day, however, and we forgive the long spells of wet and cold.
Aristotle’s swallow was the same species as our Barn Swallow. In Europe it’s called “Swallow.” As one of the most cosmopolitan species, it’s at home throughout the northern hemisphere.
My birding calendar has a new entry under April 28. In capitals. “HAWKWATCH!”
The fall hawkwatch is a big deal, marked by school field trips, birding groups, hawks-in-flight workshops. The dramatic fall flights draw crowds to certain hawkwatch hotspots. Come spring, hawk migration is more dispersed, and as mortality is high far more hawks depart in fall than return in spring. There’s no such thing as a local spring hawkwatch.
That being said, while working at the local community garden last Sunday with two friends who are ace birders, we were distracted by an Osprey, a kestrel, a Sharp-shinned Hawk, all heading north as blue sky returned.
Two days before, Don and Lillian watched over 80 hawks from their backyard during a two-hour period. Most were Broad-winged Hawks; 16 were Ospreys. That day offered a clear patch of weather surrounded by rain. Don said the hawks read weather well, and often move ahead of a cold, wet front.
Garden chores rushed to completion, we formed a mini-hawkwatch in their backyard as hawks rode wind currents along what they call “Bobcat Hill” and then Crotched Mountain across the river. Don and Lillian’s backyard is a sloping field down to a Contoocook River made wide and slow by the Bennington dam.
Migrating birds favor flyways along north-south rivers, ridgelines and coastlines. Besides navigational assistance, river corridors provide unequaled food resources and ridgelines provide updrafts to ride. The Stokeses’ backyard benefits from both river and ridgeline, but under certain conditions every backyard in the region can have hawks overhead.
Last Sunday’s “HAWKWATCH!” was the first-ever spring hawkwatch entry in my calendar. Next year the entry will remind me it’s time for the second annual spring hawkwatch.
We also watched a multitude of swallows bickering over nestboxes and foraging above the Contoocook for emerging insects. When we found a few Barn Swallows in the group, Lillian pointed to their barn where a broad hayloft door was open. Fixed open.
Besides an open door policy, they nailed small platforms to the loft rafters. As still further inducement and an experiment, they placed two decoy Barn Swallow nests (manmade) in prominent view.
Declining in New Hampshire, Barn Swallows are “a species of conservation concern” in the state. So open your garage and shed doors wide, nail platforms to the rafters, and keep your fingers crossed.
The poet Robert Lowell wrote, “One swallow makes a summer.” He’s right, too. The sight of the first Barn Swallow overhead summons summer thoughts of Barn Swallows swooping low to country fields that shimmer in the summer heat.
Note: Don’t miss the talk on climate change next Wednesday by George Hurtt from UNH. He’ll give the topic a regional and national focus, and make clear what is known with scientific certainty. As added interest to birders, he’ll explain the role of the northern forest in moderating climate change. The topic deserves a full house. Time and place: Wednesday, May 7, 7 p.m. at ConVal High School in Peterborough.
Backyard Birder appears every other week in the Monadnock Ledger.
June 20th, 2006
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