Like many people, I am fascinated by bird flight. Unlike most people, I get to study flight of Golden Eagles for a living. These large birds move through the landscape primarily by soaring—a style of flying where they hold their wings outward and rarely flap, saving them considerable energy. Instead of flapping, they rely on rising air currents to gain altitude.
Where should we draw the line between species? Biologists have debated this question for over 100 years. For much of that time, Ernst Mayr’s Biological Species Concept, which defines a species as a group of individuals that is reproductively isolated from other groups, has dominated the conversation. Recently, however, more and more evidence of hybridization between species has accumulated, especially in birds.
A number of birds that use forests disturbed by timber harvest have been declining for decades in North America’s Pacific Northwest.
Color bands, leg flags, and other field-readable marks are a core component of the ornithologist’s toolkit. Mark-resight studies have led to invaluable insights into the demographics, movements, territoriality, and migration patterns of birds. But clear, confident IDs can be hard to obtain in the field. Colors are difficult to distinguish in low light or when worn, alphanumeric codes are easily mis-remembered or mis-recorded, and was it blue on the left, red on the right, or the other way around?
Woodpeckers make holes in trees. Don’t they?
So what did we learn about how House Finch songs have changed since the 1970s—the equivalent of a millennium of cultural evolution in human terms? Here are the main results, and how we interpret them.
The first bird song I ever recorded was that of a House Finch. When I was a kid growing up in Leominster, Massachusetts, the bird that nested behind my front porch lamp would fly out to a particular birch tree or the telephone wire and belt out a complex four-second warble over and over again.
Marbled Godwits are common and conspicuous North American shorebirds. On its prairie breeding grounds, the godwit’s raucous call and proud flight display alerts all to its presence, and the species is equally obvious on its temperate nonbreeding grounds along both the Atlantic and Pacific coasts due to its gregarious nature and telltale alarm call. So how did such a charismatic species go largely undetected in Alaska until the 1980s?
Western Burrowing Owls (Athene cunicularia hypugaea) and Pulex irritans, the so-called human flea, have a curious host-parasite relationship. Although we’ve known about it for some time, many details of their connection remain unclear, including why it appears mainly in the northwestern portion of the Burrowing Owl’s range despite the fact that both species have much broader geographic distributions.
The Martial Eagle is one of the largest and most powerful of the booted eagles. These menacing giants dominate the skies over sub-Saharan Africa, ranging from Senegal to Somalia and down to South Africa.