United States Department of Agriculture
ln response to A. Marguerite Baumgartner's request for information on the phenomenon of sex reversals in wild birds "Sex Reversal in Banded Cardinal" (North American Bird Bander 11(1|:11, 19861 I would like to report a similar e_xperience and a plausible explanation offered by Dr. Kenneth Parkes of the Carnegie Museum, pittsburgh, Pennsylvania.
In eastern North America, the invasive hemlock woolly adelgid (Adelges tsugae Annand), has expanded northward at a pace that exceeds predictions from mechanistic models, suggesting successful long-distance dispersal despite the only viable dispersive phase being a flightless nymph, or "crawler." We hypothesize that migrating birds may...
The causes of bill deformities in birds have been summarized in an excellent review by Pomeroy (Brit. Birds 55:49-72, 1962). Causes include genetic mutations, disease, accident, poor nutrition, and, in caged birds, an absence of bill-filing substrates (e.g., stones, coarse bark). In wild birds, however, bill deformities are most often associated with injury to the bill...