Advances in GPS and biologging technology have greatly enhanced our understanding of wildlife ecology, providing valuable data on movement, habitat use, behaviour, and biological rhythms.

The climate is warming, and many bird species are keeping up by altering when they migrate, breed, and molt, that is, by altering their phenology. To make accurate predictions about future responses to climate warming, knowledge of the mechanisms regulating timing is needed.

While tree swallows have been the focal species in hundreds of studies, little is known about their high elevation populations. Simons et al. addressed this gap by researching a breeding population of swallows at Colorado State University’s Mountain Campus.

Before we can assess the impact of environmental factors on bird communities, it is crucial to first understand natural variation in physiological indicators.