Connecticut Warbler Oporornis agilis Scientific name definitions

Jay Pitocchelli, Julie L. Jones, and David C. Jones
Version: 2.0 — Published June 2, 2023

Priorities for Future Research


The global population of the Connecticut Warbler is declining and climate change could exacerbate these trends (72, 259, 261). The primary driver of population declines is believed to be habitat loss and fragmentation on the breeding grounds (64). Therefore, basic information on breeding biology and the effects of land-use practices on breeding birds from throughout the range should be a priority. We have learned a great deal more about the breeding biology of the Connecticut Warbler from work by Marie Christine Saulnier (27). Her use of new technologies such as digital video recording cameras placed at various nest sites and STR-1000 telemetry receivers attached to males and females have provided interesting details about parental behavior (e.g., incubation, brooding), nest sanitation, and division of labor among the sexes. However, details are still lacking on nest site selection, nest construction, fledgling and immature stages, post-breeding dispersal, nest predators, and more. Saulnier’s (27) research was conducted in mature jack pine (Pinus banksiana) forests in Quebec to assess the possible impact of blueberry farming on breeding birds. In other parts of the breeding range, the majority of the global population breeds in spruce‒tamarack bogs, muskeg, and aspen‒poplar woodlands. More information is needed from these breeding populations which have different ecological requirements and are exposed to different land use practices.

Additional information is needed on the nonbreeding period of the annual cycle. The extent of the overwintering range is still poorly known and basic research is needed on habitat selection, diet, foraging behavior, social behavior, site fidelity, and abundance on the overwintering grounds. Although we have learned more about fall migration (128, 64), the routes of spring migration and stopover ecology in general need further study. Information for these periods of the annual cycle may uncover new threats that contribute to observed population declines.

Eastern and western breeding populations have very different ecological requirements. These distinct differences in habitat preferences could influence the evolution of eastern and western populations at the genetic and behavioral levels. Comparative research on mtDNA or nucDNA from eastern and western populations may uncover genetic differences. Different habitats affect sound transmission and cultural evolution of song. Comparing physical parameters of song (e.g., frequency, duration variables) and habitat differences between eastern and western populations may reveal the extent to which acoustic adaptation has occurred and influenced the cultural evolution of song.

Although we now know that there is individual variation in song among males at the microgeographic (204) and macrogeographic (205) levels, the remainder of the vocal repertoire is poorly known. We are still lacking vocal analyses of call notes used in a variety of different behavioral contexts including male‒male territorial aggression, male‒female pre- and post-copulatory contact, anti-predator behavior, parent‒young contact, food-begging of young, etc.

Recommended Citation

Pitocchelli, J., J. L. Jones, and D. Jones (2023). Connecticut Warbler (Oporornis agilis), version 2.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.conwar.02