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black-throated blue warblers in captivity
A female and male Black-throated Blue Warbler in captivity. Photo by Jessica Deakin.

Getting to the Bottom of Male Black-Throated Blue Warblers’ Migratory Behavior

Many species of migrant songbirds have a reproductive strategy called protandry, where males arrive at stopovers and breeding sites earlier than females. Ornithologists believe that males do this because it increases their mating opportunities and reduces competition among males for high-quality nest sites. Although it’s a common phenomenon, the question of how males arrive earlier is still unanswered for most species.

graph from study
The greater the magnitude of nuthatch’s winter irruption, the lower the next summer’s breeding population.

Do Songbirds Pay a Price for Winter Wandering?

In years when winter conditions are especially harsh, birds that depend on conifer seeds for food are sometimes forced to leave their homes in northern forests and wander far from their normal ranges to find enough to eat. A new study published in The Auk: Ornithological Advances uses citizen science data to show for the first time …

Are Homebody Warblers More Likely to Sing Together?

Scientists who want to study the evolution of behavior face a fundamental problem: unlike bones, behavior generally doesn’t fossilize. However, that doesn’t mean that extinct species’ behavior doesn’t leave any evidence. The behavior of living or “extant” species can give us clues about the behavior of their ancestors, and we can use the behavior of living species, the evolutionary relationships among species, and computational modelling to make inferences about extinct species’ behavior.

scrub-jay specimens
Devon DeRaad lines up Woodhouse’s Scrub-Jays (left) and Sumichrast’s Scrub-Jays (right) to compare back color between the forms. Photo by John McCormack.

How Do Traits Change Across a Scrub-Jay Hybrid Zone?

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.

volunteer observing shorebirds
A Delaware Shorebird Project volunteer scans a flock of foraging shorebirds looking for leg flags. Photo by Jean Hall.

Resighting Errors Are Easy to Make and Hard to Measure

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?

Tracking Cultural Evolution in House Finch Song, Part 1

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.