Archive for June, 2006
Minneapolis-St. Paul Star Tribune
Fledgling: Birds that are old enough to leave their nesting site but might still be dependent on adults for care and feeding. Fledglings might or might not be able to fly at this time. The term also is used to refer to birds that have acquired flight feathers and are able for the first time to fly.
If you find a baby bird
Some baby birds found out of the nest belong there. Many young birds become mobile before they can fly, and it’s part of the natural development of some species to spend some time on the ground.
Young birds that are fully feathered are likely to have fledged, or left the nest, on their own. In those cases, the parent birds are best equipped to care for them. Well-meaning intervention by humans is usually not necessary and can be harmful.
However, if you see a sparsely feathered young bird or a bird covered only with down, it may have fallen from the nest. Return the bird to the nest if you can do so safely. If you can’t find the nest and no parent birds are in view, build a temporary nest of a small box filled with leaves or grass and secure it in a tree. Leave the area and wait for the parents’ return. If the parents don’t return in a couple of hours, bring the bird indoors, keep it warm and try to find a wildlife rehabilitator by calling a veterinarian, a local nature center or a local humane society.
For more information on caring for orphaned baby birds, call the Animal Humane Society at 763-522-4325 and ask for the baby birds discussion on wildlife info line or call the Wildlife Rehabilitation Center at 651-486-9410.
JIM WILLIAMS
June 15th, 2006
dikti.org
HARI RUJITO - POLITEKNIK NEGERI JEMBER / KELOMPOK PETERNAK WALET DESA SUMBERREJO
Masalah yang dihadapi dalam produksi sarang walet ialah tidak selalu terpenuhinya kondisi yang sesuai dengan mikrohabitat burung walet, yaitu suhu siang hari 24-29oC, kelembapan udara 85-95%, cahaya < 2 fc, dan tersedianya kabut air. Kabut air selain berfungsi membantu melembapkan dan mengatur suhu juga sebagai penarik bagi burung walet untuk masuk ke dalam gedung yang disediakan. Masalah tersebut sebenarnya dapat diatasi dengan memasang jaringan irigasi yang terdiri atas pipa semprot dinding dalam gedung disertai dengan sprinkle irigation penetralis suhu di luar gedung dan sprayer pengabut hujan buatan di halaman gedung walet.
Jaringan irigasi pipa berdiameter 1,5 inci dipasang pada seluruh dinding bagian dalam gedung. Pipa-pipa yang dilubangi kecil-kecil untuk memancarkan air dengan jarak 30 cm dialiri air terus menerus dengan memakai pompa 1,5 PK dari sumur. Pipa itu menjadi satu rangkaian dengan sprayer pengabut pembentuk hujan buatan yang berfungsi untuk arena bermain dan pemancing burung walet dan pipa sprinkle penyemprot genting yang berfungsi sebagai pendingin rumah walet dari luar. Air yang mengalir di lantai ditampung pada saluran pembuang untuk dialirkan ke kolam dan disirkulasikan lagi. Bila ada hujan atau malam hari maka aliran listrik pompa dimatikan.
Hasil pengamatan pada penerapan metode irigasi pipa dalam rumah walet menunjukkan bahwa secara efektif terjadi penurunan suhu ruangan menjadi 25oC dan kelembaban meningkat menjadi 85-90%. Dengan kondisi ini maka rumah walet tersebut ideal bagi burung walet untuk membuat sarang. Selain itu pemasangan irigasi di luar rumah walet dapat memancing burung walet untuk datang ke rumah tersebut sehingga dapat meningkatkan populasi walet di dalam gedung.
June 15th, 2006
ag.ohio-state.edu
Writer:
Kurt Knebusch
Dear Twig: Why do they call it birds’ nest soup? Is it really made out of birds’ nests?
In short: Yes. Birds’ nest soup is a Chinese dish that is made from the nest of a bird called the swiftlet. Swiftlets are small, fast birds of southeast Asia. They build their nests in groups high on cave walls. And they make those nests from something weird: saliva, or spit. Ick! The spit comes out in long, thin strands from glands that are located under the tongue. The strands are woven to make a nest that sticks to the wall like glue.
Ew. (But effective.)
It used to be the nests were harvested once or twice a year. The birds were able to raise their young. But lately, however, demand has soared. People are gathering more and more nests and are doing it more and more often.
Which, of course, is bad for the swiftlets. Scientists say their numbers are falling. If the harvest isn’t reduced, some types could be gone — extinct — in only five or 10 years.
The gooey, gluey, spitty nests actually don’t have much taste. The soup gets its flavor from other ingredients. And, contrary to folk belief, the nests have little nutritional value. They do have a special protein in them, one that boosts immunity. But cleaning the nest before cooking destroys it.
Loogily,
Twig
P.S. Swiftlet cousins in North America include the familiar chimney swift, Chaetura pelagica.
Note: Three swiftlet species are tapped for their edible nests: the aptly named edible-nest swiftlet, the also aptly named (and geographically more specific) Indian edible-nest swiftlet and the black-nest swiftlet. Some pretty thorough details about the swiftlets — their nests, the buying and selling of them, and the environmental issues — are at www.american.edu/TED/SWIFT.HTM, part of a “Trade Environment Database” Web site from American University. (Twig’s been under the weather (bug flu). This column originally ran May 9, 2004.)
“Smart Stuff with Twig Walkingstick,” a service of The Ohio State University College of Food, Agricultural, and Environmental Sciences — specifically, of the Ohio Agricultural Research and Development Center (OARDC) and Ohio State University Extension, both part of the College — is a weekly column for children about science, nature, farming and the environment. For details and to receive Twig free by mail, e-mail or fax, contact Kurt Knebusch, News and Media Relations, CommTech, OSU/OARDC,1680 Madison Ave., Wooster, OH 44691, knebusch.1@osu.edu, (330) 263-3776. Available online at extension.osu.edu/~news/archive.php?series=science.
June 14th, 2006
pontianakpost.com
Singkawang,-Â Asosiasi Pengusaha Walet (APW) Kota Singkawang yang baru saja terbentuk harus memperhatikan masalah penempatan bangunan sarang walet. Bangunan yang ada jangan sampai menganggu lingkungan sekitarnya yang dapat merusak kesehatan dan mengusik bangunan lainnya di kota ini.
“Kita dukung pembentukan APW di kota ini. Mengingat usaha walet ini dapat meningkatkan PAD. Namun demikian, asosiasi ini harus memperhatikan bangunan walet yang selama ini tidak tertata dengan baik,” kata David Junaidi SE,
Sekretaris LSM Lembaga Pengembangan Masyarakat Kota (Gaspemasta) Singkawang. Pembangunan yang ada, harus ada kriteria-kriteria. Sehingga bangunan walet tersebut akan tersusun rapi dan bebas dari hal-hal yang dapat mengundang penyakit. Tapi alangkah lebih baik lagi, bila pembangunan rumah walet itu dibangun di pinggiran-pinggiran kota yang jauh dari pemukiman masyarakat. Sebagai contoh, di daerah manggis perkuburan Tionghoa (perbatasan Singkawang Barat dan Singkarang Tengah). Menurut dia, dengan adanya bangunan sarang Walet di daerah pinggiran kota, selain dapat menjaga keindahan kota itu sendiri juga dapat meningkatkan PAD Kota Singkawang. Serta menambah lapangan pekerjaan baru bagi masyarakat setempat.
Hanya saja, untuk merealisasikan itu semua diperlukan dukungan dari Pemerintah Kota Singkawang melalui perda walet. Dalam perda itu bisa diatur tata letak bangunannya seperti apa, dengan memperhatikan kriteria-kriteria seperti disebutkan sebelumnya. Tujuannya agar setiap pengusaha walet tidak sembarangan untuk membangun rumah walet itu sendiri. “Kalaupun mereka berani melanggar aturan yang sudah ditetapkan dalam perda, maka yang bersangkutan akan menerima sanksinya sebagaimana tercantum dalam perda itu,”demikian David.
Untuk itu, Gaspemasta mengingatkan kepada pemerintah kota Singkawang untuk segera membahas perda walet yang sudah diajukan draftnya oleh Dinas Agribisnis Kota Singkawang. Jangan terlalu lama mengendap di keasistenan sebelum bermunculan rumah-rumah walet yang bertentangan dengan pola kehidupan bermasyarakat kota Singkawang.
“Lebih cepat membahas perda maka akan menjadi lebih baik,”katanya lagi. Kepada APW sekali lagi ia mengingatkan untuk sementara ini agar dapat terus memperhatikan bangunan-bangunan walet yang akan dibangun di tengah-tegah masyarakat kota Singkawang. ‘Sesama pengusaha hendaknya saling mengingatkan ketika akan membangun rumah walet, bangunlah dengan memperhatikan lingkungan sekitarnya,”tambahnya. (vie)
June 14th, 2006
.kapet.org
BALIKPAPAN ternyata bukan hanya dikenal memiliki potensi sebagai kota transit, tetapi juga memiliki potensi bisnis rumah walet yang cukup besar. Namun sayangnya, hingga kini potensi agribisnis ini belum tergarap maksimal karena dipandang sebagai bisnis yang mengandalkan hoki. Menurut pengamat walet Ir Herman, 90 persen penghasil sarang burung dengan liur ini berjenis walet (collocalia fuciphaga) bukan seriti seperti di Pulau Jawa. “Berdasarkan pengamatan saya beberapa tahun terakhir, jenis walet lebih mendominasi yakni sekitar 90 persen. Tidak seperti di Pulau Jawa hanya 40 persen, sementara 60 persen lagi adalah seriti,” ungkapnya.
Dengan fakta ini, pengembangan rumah walet di Balikpapan memiliki prospek yang besar karena tidak memerlukan dua perlakuan seperti di Pulau Jawa. Pengembangan walet mesti lewat pengeraman telur di sarang seriti dulu, baru walet diperoleh. Berbeda dengan Balikpapan walet telah tersedia dalam jumlah banyak, tinggal mengelolanya lewat rumah walet.
Letak Balikpapan yang berada di pinggir pantai, dekat dengan goa-goa, suhu yang cocok dan memiliki sumber makanan melimpah bagi walet terangnya menjadi faktor pendukung yang sangat bagus untuk bisnis ini. Sementara hingga kini, Balikpapan baru memiliki 15 rumah walet, lima diantaranya adalah rumah baru. Padahal dalam satu kecamatan rumah walet bisa dikembangkan antara 60-70 buah. “Jadi potensi rumah walet masih cukup besar,” tegasnya.
Dengan pengelolaan yang telaten dan penggunaan teknologi yang benar ia yakin potensi sarang walet di Balikpapan bisa tergarap secara maksimal. Berdasarkan hasil penelusurannya sedikitnya Balikpapan memiliki 150 ribu burung walet dan diperkirakan dalam setahun bisa memproduksi 1 ton sarang walet. “Sementara yang tergarap masih kecil,” katanya.
Mengenai lokasi, beberapa titik di Balikpapan masih memiliki potensi untuk pengembangan rumah walet. Kilometer 5,5 sebut Herman salah satu kawasan yang bisa dikembangkan untuk bisnis ini. “Bila dikelola secara benar kami perkirakan dalam tiga tahun investasi dibisnis ini akan kembali,” katanya.
Namun Herman menambahkan potensi walet yang ada di Balikpapan juga dipengaruhi oleh kondisi walet di gua-gua sekitar Balikpapan. Pasalnya walet yang akan bersarang ke rumah walet sebagian berasal dari gua-gua.(bz)
[reported by: KAPET Sasamba]
June 14th, 2006
By Cristin Ross
Athens Review Online
If you’ve driven under the bridges of Loop 7 in Athens on any given morning lately, you may have noticed flurries of winged activity along the sides of those bridges.
That would be your typical cliff swallow, making the most of a morning meal — mostly likely mosquitoes.
Like its close relative the Barn Swallow (Hirundo rustica), the cliff swallow (Petrochelidon pyrrhonota) has benefited from the proliferation of manmade nesting sites, reports the Cornell Laboratory of Ornithology. Once restricted to nesting on the cliff faces of the west, cliff swallows, which eat only insects, now most often nest under bridges, culverts, and under the eaves of buildings.
“These birds are fairly common in East Texas,” said Texas Parks and Wildlife biologist David Sierra. “I think highway bridges are the equivalent of blue bird nest boxes for a cliff swallow, and the greater numbers of these bridges and other structures they can use are helping their populations grow. That’s good for us, since they eat a huge amount of those flying insects that tend to bug us.
“They are very agile flyers, so they seem able to adapt to traffic well, so traffic under a bridge poses a minimal threat to them.”
According to the Cornell Web site, www.birds.cornell.edu, the bird was first noted breeding in New York in 1817 and became widespread by the beginning of the 20th century. Declines followed the introduction and spread of the House Sparrow, a species that may dispossess cliff swallows by taking their nests and destroying any eggs already laid. The modern practice of painting wooden barns and of using metal or other smooth materials has also apparently inhibited cliff swallow nesting, but the use of bridge and dam sites for their nests seems to be increasing.
“It takes a long time to build a nest,” Sierra said. “And most nesting pairs will come back to a nest year after year, so don’t knock them down, thinking they aren’t of any use anymore.”
Cliff swallows build gourd-shaped nests out of mud pellets that they carry in their mouths to a nest site protected by an overhang. The typical nest contains approximately 1,000 mud pellets when finished, and is lined with grasses and feathers.
“Their spit is kind of sticky and that helps to form the pellets and adhere them to the rest of the nest and to the side of the bridge,” Sierra said.
Usually a nest is grayish in color, but the nests of those birds in Athens are the distinctive red-orange color indicative of East Texas red clay.
Nests, begun as a shelf adhered to a vertical surface, are located in colonies averaging a few hundred nests and ranging up to two or three thousand in the west.
A colony serves as an “information center” for feeding birds, as unsuccessful foragers may follow successful birds to food sources. Both sexes share in incubating and feeding chicks.
The species is migratory and spends the winter in more tropical climates, including South America.
Cliff swallows have glossy blue-black backs streaked with white and a cinnamon rump. The wings and square tail are brownish black. Underparts are white with the upper breast sides and flanks pale gray brown. The throat and sides of the head are chestnut. Below the throat is a patch of black at the top of the breast. The forehead is white to pale brown. Both sexes look alike.
In the United States, all swallows are classified as migratory insectivorous birds under the Migratory Bird Treaty Act of 1918, as found at the Web site www.ces.ncsu.edu. Swallows are also protected by state regulations. It is illegal for any person to take, possess, transport, sell, or purchase swallows or their parts, such as feathers, nests, or eggs, without a permit. As a result, certain activities affecting swallows are subject to legal restrictions.
June 13th, 2006
Gazette Extra Sports
(Published Friday, June 9, 2006 09:54:00 AM CDT
Associated Press
NEENAH, Wis. - A bridge project in Neenah has gone to the birds.
The Oak Street bridge will take at least an extra two months to complete because of the arrival of hundreds of nesting cliff and barn swallows.
The birds aren’t expected to change the route of the Fox Cities Marathon on Sept. 24, but they’ve certainly ruffled feathers of city officials because the birds are federally protected.
The swallows have built mud nests on the temporary support structure on the underside of the new $5.6 million bridge.
“The falsework will stay there until the swallow nesting period is completed,” said Bill Bertrand, project manager for the state Department of Transportation’s regional office in Green Bay.
The birds are expected to continue nesting through August 20. It means that motorists will have to continue using another detour to get across the Fox River.
Bertrand said the bridge contractor can continue to work above the bridge deck, but he said it will have another two months of work after the falsework is removed.
The bridge was expected to open at the end of July, several months ahead of schedule.
“Everything had been so favorable that we thought we would have an early opening, and then this comes along,” Neenah Mayor George Scherck said.
Cliff and barn swallows like to nest on manmade structures like bridges, and aren’t part of a larger conspiracy, as Scherck joked.
“Even the birds are against us here,” Scherck said. “If it wasn’t so sad, you would probably laugh.”
June 13th, 2006
solusisehat.net
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Kendati penelitian menyebutkan burung wallet tidak menularkan flu burung, namun masyarakat harus senantiasa waspada. Sebab suatu saat bukan tak mungkin burung ini juga bisa menjadi pembawa virus tersebut.
Kepala Dinas Peternakan Riau Marzuki Husin mengungkapkan berdasarkan sampel, tidak ditemukan sedikit pun virus flu burung pada burung walet. Enam fakultas yang melakukan penelitian itu di antaranya Fakultas Kedokteran Hewan Institut Pertanian Bogor (IPB), Universitas Sriwijaya, Hasanuddin serta Udayana.
Ia memperkirakan burung ini bebas virus karena tidak bersentuhan langsung dengan daratan. “Pekiraannya begitu, namun sekali lagi saya katakan, kita harus senantiasa waspada,” ujarnya lagi.
Di Riau dengan 11 kabupaten dan kota, terdapat sejumlah penangkaran walet tidak resmi. Penangkaran itu dibuat dari bangunan tinggi. Di kawasan pinggir sungai atau pantai, seperti Dumai, Bengkalis, dan Inhu, ruko yang sengaja dilobangi untuk keluar masuk dan bersarangnya burung sangat mudah ditemui.
Sejak flu burung mulai menginfeksi unggas di Kota Dumai, masyarakat di beberapa kota sentra budidaya burung walet mulai khawatir. Sebab daya jelalah burung walet ini sehari mencapai 300 km.
Masyarakat juga meminta agar pemda mengkaji ulang keberadaan budidaya sarang burung walet di tengah perkotaan ini. Ia juga meminta agar merelokasinya ke daerah yang tidak berada dalam pemukiman penduduk.
Sumber: PdPersi
June 12th, 2006
by Raleigh J. Robertson Department of Biology, Queen’s University, Kingston, Ontario K7L 3N6 and Jason Jones
Spatial and demographic effects on Tree Swallow nest quality and reproductive success
The reproductive success of Tree Swallows (Tachycineta bicolor) is affected by a number of factors. For populations nesting in natural cavities, ecological factors such as cavity volume, predation and nest usurpation are often the primary determinants of reproductive success (Rendell and Robertson 1989; Robertson and Rendell 1990; Robertson et al. 1992). For Tree Swallows occupying nest-boxes, these factors are usually not important because the researcher’s use of predator guards almost eliminates predation, use of uniformly-sized boxes controls for effects of cavity volume on clutch size, and boxes with carefully designed entrance dimensions reduce nest usurpation by competitor species such as European Starlings (Sturnus vulgaris), Common Grackles (Quiscalus quiscula) and Northern Flickers (Colaptes auratus) (Rendell and Robertson 1991). However, in nest-box studies, other factors can influence reproductive success either directly or potentially through an effect on nest quality. Some researchers (e.g., McCarty and Secord 1999a, b) have evaluated the potential effects of exposure to chemicals in the environment on nest quality and/or reproductive success in Tree Swallows. However, there are other variables that can have a major impact on these endpoints. Inter-nest spacing, proximity to forest edge, timing of settlement and nest-building, availability of nesting material, history of the nest-box or grid, and age of the breeding pair could all affect nest quality and/or reproductive success: (i) Inter-nest spacing may affect nest-building and productivity since competitive interactions become more intense when boxes are close together (Muldal et al. 1985;
Tree Swallow nest quality & reproductive success page 3 Mitchell and Robertson 1996), so birds may spend more time in nest-box defense, and less time in other nesting activities. (ii) Proximity to edge of an open area, where shrubs or trees are close to the nest-box, may have an effect since House Wrens (Troglodytes aedon), which occupy shrub habitat, may interfere with Tree Swallow nesting (Rendell and Robertson 1990). (iii) A trend of reduced breeding success as the season progresses has been established (Stutchbury and Robertson 1988); hence, settlement date and/or the time of nestbuilding may also affect quality of the nest, and reproductive success. (iv) The type and availability of nesting material may also affect nest quality, hatching success and fledging success. The type of nesting material will likely vary from site to site, as will the availability of feathers to use as nest lining (usually waterfowl feathers). The type and number of feathers probably vary as a function of wind exposure, whether there is flowing or standing water, and the local population of waterfowl or other birds. Hence, availability of nesting materials may affect nest quality and in turn, reproductive success. (v) The history of an individual nest-box within a grid, or of the entire nest-box grid, may influence the quality of nests and potentially reproductive success. Since birds often return to the same box to breed, the history of a given box (i.e. old or new) may be related to the likelihood of being occupied by an experienced female or pair, which in turn may affect nest quality and/or reproductive success. Also, a grid with a long history is likely to have a stable population with many returning birds, compared with a newly established grid, which would likely have a younger age distribution, plus more breeders new to the study site. (vi) Finally, female age may have an effect on nest quality and/or reproductive success, with younger, inexperienced females expected to build less substantial nests, and also to have reduced reproductive success (Stutchbury and Robertson 1988). Similarly, male age could have an effect through the male’s ability to compete for nest-lining feathers, or his ability to assist with feeding nestlings. Unless all of these factors are carefully controlled, it is difficult to pinpoint a single causal factor as being responsible for any differences between study sites in either nest quality or reproductive success. Moreover, it is not clear that nest quality affects reproductive success in Tree Swallows. Several studies that have evaluated this issue (e.g., Winkler 1993; Lombardo et al. 1995; McCarty and Secord 1999a) have reached varying results. The purpose of this study was to determine the effects of (i) inter-nest spacing, (ii) proximity to forest edge, (iii) settlement and nest-building date, (iv) availability of nesting material, (v) history of the nest-box, and nest-box grid and (vi) female and male age, on both nest quality and reproductive success of the Tree Swallow. In addition, this study evaluated the impact of nest quality on reproductive success. METHODS We conducted this study using existing grids of nest-boxes, as well as adjacent, newly established grids, at the Queen’s University Biological Station (QUBS), 50 km north of Kingston,
June 12th, 2006
anbg.gov.au
These two groups of fungi have a superficial similarity. Both produce cup-like fruiting bodies that contain tiny “eggs”, or peridioles. While each Cannonball fungus fruiting body contains just one peridiole, there are many in a Birds Nest fruiting body. However, despite the similarities in appearance the two groups are only distantly related and they release their spores in quite different ways. In this section you’ll find out how the spore-containing peridioles are released.
There are several explanatory diagrams in this section. The particular colours that are used have no meaning and are used simply to help distinguish various features. The diagrams are also slight simplifications of reality, since their sole aim is to illustrate the important features.
Birds Nest Fungi
Cyathus novaezelandiae is an example of a Birds Nest Fungus. In the photograph you can see the egg-like peridioles in each fruiting body. The cups of the Birds Nest Fungi have a somewhat leathery consistency and each peridiole has a hard outer casing, within which there is a mass of spores. The cups vary in size but generally are between 5 and 10 millimetres in diameter.
In the case of Birds Nest Fungi, the peridioles are knocked out of the cups by raindrops. When a peridiole lands somewhere - it sticks. In some genera of Birds Nest Fungi the peridioles have sticky surfaces, but that’s not the case in the genera Crucibulum and Cyathus. In these genera the peridiole has a long tail and the end of the tail is sticky and adheres to any surface it comes into contact with. The photograph
shows some tailed peridioles from a specimen in the genus Cyathus. Each peridiole is about 2 millimetres in diameter.
Before the peridiole is ejected, the tail is compressed into a small knob. The diagram shows a peridiole (dark brown) and the knob (lighter brown), as well as an enlarged view of the knob’s contents. The knob has a thin casing, called the purse, and this is the light brown area. Within the purse the tail (or funicular cord) is compressed in a zig-zag fashion. The sticky end (or hapteron) is shown in black and the rest in red. Furthermore, the lower end of the purse is attached to the inner wall of the cup by hyphal strands (shown in grey).
When a raindrop forces a peridiole out, the grey hyphal strand initially stretches a little, but soon reaches its maximum possible extension and becomes taut. By now the peridiole has considerable momentum and the tautness of the hyphal strand results in the lower end of the purse being broken. This lets the peridiole continue its journey. There are two schools of thought as to what hap
Hypothesis 1
One school of thought holds that as soon as the purse is ruptured the cord extends, so that the peridiole flies through the air trailing its tail. So the entire sequence would be as shown in the accompanying diagram. In the first figure you can see a blue raindrop falling towards the cup. In the second figure the raindrop has hit the peridiole-filled cup and has dislodged one brown peridiole. You can see it just beginning to leave the cup. Finally, in the third figure, the peridiole has escaped the cup and is now trailing a red tail with a black terminal segment.
The tail is made up of a number of hyphae and the black, terminal segment is sticky. As the peridiole flies through the air, the tail may swing about a bit and if the sticky segment hits something (such as a grass blade), it attaches itself straight away so that the flight of the peridiole stops. With the end of the tail now stuck, the rest of the tail just wraps around the grass blade and the peridiole comes to rest on that grass blade. Have you ever thrown a ball-on-a-string and then had it get caught in a tree? If so, you’d know just how well the string can wrap itself around a branch. Under hypothesis 1 a peridiole-on-a-tail would be very much like a miniature version of that ball-on-a-string.
Hypothesis 2
The other school of thought holds that the tail doesn’t immediately extend. The peridiole flies through the air with just the sticky end of the tail exposed. Now when the peridiole hits an obstacle the exposed sticky end could immediately adhere to that obstacle. The peridiole would still keep moving since the examples we are now looking at involve species with non-sticky peridioles. The continued movement of the peridiole would now draw out the tail, which can extend considerably, but after a very short time the peridiole would be reined in and brought to a stop.
The splash-cup mechanism isn’t restricted to Birds Nest Fungi. For example, in the Plant Kingdom you can see similar splash-cups in liverworts of the genus Marchantia . The circular splash-cups hold gemmae, which are small, spherical propagules composed of a mass of liverwort cells. If a gemma lands in a suitable place it will grow into a new Marchantia plant. The gemmae are not spores, but are means of vegetative (or clonal) propagation. Each spherical gemma is a bit like a miniature “cutting” from the parent. The Marchantia gemmae cups are only a few millimetres in diameter. It is interesting to see that two quite different (and unrelated) groups of organisms have, independently, come up with the same solution to the problem of dispersing reproductive units.
History
While Birds Nest Fungi caught the eyes of various early botanists, it took a long time to discover the splash-cup method of peridiole dispersal. In 1686 the English naturalist John Ray thought that they were dispersed by rainwater which, once it had filled the cup, would overflow and so carry the peridioles with the overflow. In 1855 Julius Sachs cast doubt on the washing-out theory. Over three years he had observed some Birds Nest Fungi that grew on a small wooden bridge in the Canal Garden at Prague. This bridge was often completely under water during spring floods, but Sachs found no Birds Nest Fungi on another wooden bridge, about a hundred yards downstream. He had noted that the peridioles could float and that the spores germinated after being immersed. So, from the absence of the fungi from the other bridge, he concluded that the peridioles were not as easily washed out as had been supposed.
In between Ray and Sachs (and after) there were other hypotheses. Some supposed that the peridioles were ejected by some elastic or spring mechanism and in 1877 one mycologist proposed that animals (presumably small ones!) sought out peridioles for food and carried them out of the cups when the cords became entangled
in the animals’ feet. The first suggestion of the splashing mechanism came in 1927 when George W Martin wrote that “…the peridioles could easily be spattered out of the cups by dropping water into them from a pipette a couple of feet above them.”
However, the significance of Martin’s observations didn’t appear to sink in for some years. In 1941 AHR Buller commenced a series of dispersal experiments with Birds Nest Fungi in which he was soon helped by Harold Brodie, who continued the studies after Buller’s death in 1944. These experiments showed that the raindrop mechanism is quite effective. The procedure was fairly simple:
Fix a Birds Nest Fungus fruiting body to a cork slab and put it in the middle of the laboratory floor.
Let water drops fall into the cups from a burette, positioned high up. The laboratory ceiling was high enough to allow the drops to fall 9 feet - thereby ensuring they were approaching terminal velocity by the time they hit the cup.
Search for peridioles on the laboratory floor and measure their distances from the cup. To make it easier to find the peridioles, spread white butcher’s paper over the floor.
After experimenting with various species, the results were that the peridioles splashed out for distances ranging from just a few centimetres to a little over two metres. Mostly the distances were between 30 centimetres and a metre. You can find out about these experiments (and much more about the Birds Nest Fungi) in Brodie’s book, given in the reference button. Brodie also highly recommended standing out in a rainstorm, watching peridioles being splashed out of Birds Nest Fungi! He also quotes an anonymous friend’s thoughts
Trivia
In 1843 JC Zenker described a new fungus on the leaves of Camellia plants. Zenker didn’t say where he’d found the plant and fungus, but presumably in Germany, where he lived. This fungus produced small black pads, about two millimetres in diameter, and Zenker gave it the name Leptostroma camelliae. Interestingly, though Camellia plants were widely cultivated, there were no other reports of this fungus turned up until 1933, in the United States. In that year some specimens were sent to William Diehl of the US Department of Agriculture. Diehl wrote that he was “…impressed by the startling reappearance of Zenker’s species after a lapse of nearly a century” and thoroughly investigated the new samples. His conclusion: the black pads were nothing but the peridioles of a Birds Nest Fungus. A re-examination of Zenker’s published drawings showed evidence of the cords on his pads as well. So, after 90 years, this mystery fungus was laid to rest! Since the peridioles can stick very firmly, they may often look like outgrowths, rather than something stuck on. So Zenker’s mistake is understandable.
The Cannonball Fungus
Whereas the Birds Nest Fungi are passive in their spore release and rely on raindrops to do all the work, the Cannonball Fungus (Sphaerobolus stellatus) is very active. When immature the whole fruiting body is a closed sphere. In the photograph you can see a line of immature fruiting bodies, going right (and slightly upward) from the centre of the photo.
At maturity the outer covering splits radially, from the apex of the sphere, leading to the creation of a toothed cup, more-or-less hemispherical in shape. The number of teeth vary between four and eight. If you look at the various open fruiting bodies in the photo, you’ll see that the cups do indeed have toothed (rather than Each cup is about 2 millimetres in diameter and consists of a firm outer case and an inner membrane - with a single reddish-brown peridiole sitting on that membrane. The membrane is attached to the outer cup at the tips of the teeth mentioned above. Within the cup, the peridiole sits in a bath of fluid. If you look at the open cup near the lower left of the photo, you can see evidence of this fluid in the way the flashlight has been reflected
When the fruiting body is mature the inner membrane turns inside out and flicks the peridiole into the air. The process is shown in the diagram, where there is a grey outer cup, orange-brown inner membrane and dark brown peridiole. The blue dots represent the fluid bath. The fluid in which the peridiole sits acts as a lubricating fluid. It keeps the peridiole loose in the cup, so that it is very easy to flick away.
Though the whole structure is only a couple of millimetres in diameter, the force of ejection is powerful enough to shoot the peridiole up to 6 metres away - so earning this fungus common names such as Cannonball Fungus or Artillery Fungus. Once the peridiole has been ejected, the inner membrane can collapse a little. In the photo you can see quite a few such collapsed membranes. The inversion of the membrane takes between a thousandth and a fifteen-hundredth of a second. The peridiole is shot off with an initial speed of around 3-5 metres per second. Unlike the peridioles in Birds Nest Fungi, the Sphaerobolus peridiole is fairly soft. It is composed largely of fatty materials. It compresses when it hits a solid object and stays firmly stuck.
More about the shooting process
In the first part of the Cannonball Fungus section, you’ve been told what happens - the membrane turns inside out. You don’t have to read any more if you are quite satisfied with simply knowing what happens. The rest of this section goes into a more detailed explanation of how it all happens and what roles the various parts of the fruiting body play.
The accompanying diagram will help make sense of things. The figure on the upper left depicts the firm outer cup (shown in grey), the inner membrane (shown in red and black), an air layer (white) between the cup and membrane, the peridiole (brown) and the fluid (blue stippling) in which the peridiole is immersed.
The inner membrane is composed of two layers. The red layer is formed by a palisade of mostly elongated cells, arranged radially (that is, oriented at right angles to the surface of the membrane), while the black layer consists of hyphae that are oriented more or less tangentially. The figure on the lower left shows a stylized, enlarged view of a small portion of the inner membrane, with the same red/black colour conventions.
The red layer of palisade cells absorbs water and so would expand laterally, but this expansion is held in check for a while and so builds up stresses. It is the release of these stresses that shoots the peridiole away.
One school of thought holds that though the red cells tend to expand, the non-swelling black hyphal layer holds the lower parts of the red layer firmly together. The other school of thought holds that the black hyphal layer plays no important role. Rather, the palisade cells are tightly packed and slightly pear shaped, broadest in the upper parts (which would swell more than would the lower areas).
Regardless of which explanation is correct, the result is the same. Stresses are created because within the inner membrane, the upper areas would expand more than the lower areas. While these stresses are building up, teeth in the outer cup continue to bend outwards, and so the outer cup continues to open. Eventually there comes a point when the outer cup has opened enough to allow the stresses to be released by the inner cup suddenly turning inside out - thereby flicking the peridiole out quite forcibly. This is shown in the figure on the right of the diagram.
Why do the palisade cells absorb water? At maturity there is a high sugar concentration within the cells and the cell walls are semi-permeable. The walls allow some substances (such as water) to move into or out of the cell - but numerous other molecules are unable to cross the barrier. Such semi-permeable cell walls are an important feature in all living organisms.
Suppose you have two compartments (A and B), separated by a semi-permeable membrane. Let both compartments be filled with water and add sugar (red dots) to B. It is a fact of physics that water will be drawn from A into B. The same water movement will occur even if some sugar is dissolved in A - as long as the sugar concentration in A is less than the concentration in B. Such fluid flow (across a semi-permeable membrane, from lower to higher sugar concentration) is called osmosis. In the case of Sphaerobolus each of the palisade cells is like compartment B, so water will be drawn in and the cells would expand if possible. For the mechanism to work, a high level of humidity or damp surrounds are necessary. Experiments show that a “loaded” Sphaerobolus won’t fire if it dries out.
Before maturity, there are no sugars in the palisade cells. Instead, there is glycogen, a polymer composed of numerous simple sugar molecules joined together. However, glycogen has virtually no osmotic effect and so the swelling of the cells does not occur in the immature fruiting body. As the fruiting body opens and matures, the glycogen is converted into sugar molecules.
Two other important points are the air layer between the inner membrane and the outer cup and that the membrane and cup are attached only at the teeth. Given the air layer, there is no danger of the inner membrane sticking to the outer cup. The fact that attachment is only at the teeth, means that the air layer is in contact with the outside air. Consider the accompanying diagram, which shows an eight-toothed Sphaerobolus fruiting body viewed from above. You can see the peridiole on the red inner membrane, with the margin of the outer cup shown in grey. Since the teeth are the only points of attachment between the membrane and cup, in each shallow, V-shaped notch between neighbouring teeth there is a gap (shown in white) between the inner membrane and the outer cup.
These gaps allow the air layer between the membrane and cup to be in contact with the outside air. When the membrane inverts, those gaps between the teeth allow outside air to move quickly into the expanding space between the membrane and cup. If the membrane were attached by all of its circumference, there would be no gaps and the air layer between the membrane and cup would be cut off from the outside air. In that case, the inverting membrane would be fighting against a partial vacuum. That would greatly slow the movement of the membrane and the peridiole would be shot out only a short distance
June 8th, 2006
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