The largest comparison yet of his-and-hers bill lengths in hummingbirds shows that the more the difference in color between sexes, the longer the females’ bills tend to be.
The survey of 166 species also linked bill length and breeding systems, reports Robert E. Bleiweiss of the University of Wisconsin-Madison in the Dec.
Log in
Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.