Why are ornithological studies so focused on the breeding stage? A test of hypotheses

Unequal representation of focal research areas can arise during the initial stages of project development when investigators make decisions about what, when, and where to study. Regarding when research is conducted, publications on vertebrates are strongly skewed toward breeding-stage studies, leaving sizeable gaps in our knowledge pertaining to behavior and demography in nonbreeding stages. Here, we quantified how the focus on different annual cycle stages has changed over the past 64 years in the field of ornithology, and tested 3 hypotheses to explain underlying correlates of the focus on different stages. We surveyed field-based studies published in Ornithology from 1960 to 2024 and documented the annual cycle stages examined, regions of study, migratory strategies of focal species, and author affiliation for each paper. The tendency to conduct breeding-stage research in ornithology became more, rather than less, pronounced over the 64-year interval, and breeding-stage research was more common when field work focused on migratory species. Therefore, investigators, authors, and editors could likely increase representation of other annual-cycle stages by supporting, conducting, and publishing more studies in the tropics and more studies using remote tracking technologies. More nonbreeding and year-round studies are necessary to fully understand the ecology and evolution of species and develop the most effective strategies for conservation.