Friday, October 14, 2016

Spider Web Season

It's been a warm October so far, though we are entering a few stormy days. This is the time of year when spiders launch themselves into the air to disperse. From an exposed perch, some spiders release a streamer of thin silk until the wind picks up the silk and the spider. This is a way that a species can distribute itself to new terrain. Of course, the spiders can't steer their flight and many will be carried into inhospitable habitat. Warm daytime updrafts in our sunlit canyon will loft thousands of meters of spider silk up along the cliffs. If you shield your eyes from the sun you're certain to see streamers of spider silk sailing above; binoculars reveal these non-winged invertebrates hundreds or thousands of feet up. Arachnologists refer to this behavior as 'ballooning' but I prefer the term 'kiting' as the lengths of silk are more like kite tails. Sailing spiders form a part of the community of aerial plankton - that's a real term for the column of insects, spiders, and other things adrift in the skies. When updrafts swirl in canyon eddies, great clots of spider silk form in the sky. When lift ceases or the clumps become too heavy, they drop to the ground and we get a glimpse of this marvelous behavior of something that can't 'fly' but can soar. Spider silk clots show up well on pavement, but they're a little harder to pick out forests and meadows.

The sugar maple in Old Yosemite Village is at its peak color. Our native deciduous oaks, maples and especially dogbane are also colorful now. The Merced is below average at 18 cfs, but will be starting its annual rise tonight. We hope that Yosemite Falls will return to visible flow this weekend.