Birds and spiders
Observations by amateur naturalists help paint a detailed picture of opportunistic spiders
Published: October 16, 2012
A researcher who reviewed the accounts of amateur naturalists along with the papers of professional scientists has shed light on a largely overlooked natural hazard to birds -- spider webs.
A Carolina Chickadee perches next to a spider's web.
Daniel M. Brooks, the curator of vertebrate zoology at the Houston Museum of Natural Sciences, sent requests for information to the Neotropical Ornithology, Ornithology, and other avian listservs in 2007 and received reports of 69 cases of birds trapped in spider webs.
All but one of the records in which the spider was described identified the web builder as an orb weaver. Orb weaver webs can extend over three feet in radius.
More than 50 bird species were reported, including three swallows, three flycatchers, three New World finches, three sparrows, four sunbirds, five warblers (Virginia's, Yellow, Yellow-Âthroated, Common Yellowthroat, and American Redstart), and nine hummingbirds.
Ruby-throated Hummingbird was the bird species entrapped most often. Tiny Little Hermit and Vervain Hummingbird (0.07 oz., 2 g, each) were the smallest. The largest was Laughing Dove (2.82 oz., 80 g).
More than half of entangled birds were released unharmed by the person who reported the incident, Brooks writes. Of those not released, almost three quarters died as a result of their entrapment. Only birds that were not wrapped in silk were able to free themselves naturally.
Brooks writes that his research, besides describing a natural hazard to birds, illustrates the importance of keeping good field notes and reporting interesting observations. His analysis, he writes, "would not have been possible without the careful records of others, including amateur naturalists who reported their field notes."
He described his findings in the June 2012 issue of The Wilson Journal of Ornithology.