Posted by: atowhee | July 15, 2016

BLOWING IN THE WIND

In the air: Vaux’s Swifts, Turkey Vulture, an occasional Bald Eagle…and spider webs. Most of the webs around our garden are built by small spiders and are attached to structures and trees.WEB1 WEB2Click here for a link that shows spider weaving an orb web…in slo-mo with pianist accompaniment.

Web-weaving spiders have several spinnerets on their abdomen. Each spinneret produces a SPECIFIC kind of silk, of which there are several varieties, some thinner than others, some sticky, some simply used for structural strength.

The web silk is quite thin and can only be seen because of reflected light.  The silk is strong enough to stop an insect in flight, yet it is also flexible and can stretch up to 40% (nylon can do about 20%).  Yet the silk has more strength than steel fibers of the same diameter.  Spiders have been evolving their use of silk for at least 100-million years.

The web silk contains a lot of protein and the spider often eats the web on the morning to re-capture that protein.

Here’s description of spider silk on a University of Bristol website: “The dragline silk of the Golden Orb-Weaving spider is the most studied in scientific research.  Spider silk is a natural polypeptide, polymeric protein and is in the scleroprotein group which also encompasses collagen (in ligaments) and keratin (nails and hair).  These are all proteins which provide structure.  The protein in dragline silk is fibroin (Mr 200,000-300,000) which is a combination of the proteins spidroin 1 and spidroin 2.  The exact composition of these proteins depends on factors including species and diet.  Fibroin consists of approximately 42% glycine and 25% alanine as the major amino acids.  The remaining components are mostly glutamine, serine, leucine, valine, proline, tyrosine and arginine.  Spidroin 1 and spidroin 2 differ mainly in their content of proline and tyrosine.”

roughieRough-winged Swallow above.   Warbling Vireo showing his belly: wavi2Wood-Pewee in the bright sun. wpw looksIt was another glorious, blue-sky day:sky1Wennerberg’s oaks were waving gently in the soft afternoon breezes along North Yamhill River: sky2

Wennerberg Park, Carlton, OR, Yamhill, Oregon, US
Jul 14, 2016 4:00 PM – 4:45 PM
8 species

Turkey Vulture (Cathartes aura)  X
Western Wood-Pewee (Contopus sordidulus)  1
Warbling Vireo (Vireo gilvus)  1
Northern Rough-winged Swallow (Stelgidopteryx serripennis)  1
Bewick’s Wren (Thryomanes bewickii)  1
American Robin (Turdus migratorius)  10
Purple Finch (Haemorhous purpureus)  1
House Sparrow (Passer domesticus)  X

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