Atmospheric pressure predicts probability of departure for migratory songbirds

  • May 1, 2023
  • by Nathan W. Cooper, Bryant C. Dossman, Lucas E. Berrigan, J. Morgan Brown, Dominic A. Cormier, Camille Bégin‑Marchand, Amanda D. Rodewald, Philip D. Taylor, Junior A. Tremblay & Peter P. Marra


Background: Weather can have both delayed and immediate impacts on animal populations, and species have
evolved behavioral adaptions to respond to weather conditions. Weather has long been hypothesized to affect the
timing and intensity of avian migration, and radar studies have demonstrated strong correlations between weather
and broad-scale migration patterns. How weather affects individual decisions about the initiation of migratory flights,
particularly at the beginning of migration, remains uncertain.

Methods: Here, we combine automated radio telemetry data from four species of songbirds collected at five breeding
and wintering sites in North America with hourly weather data from a global weather model. We use these data to
determine how wind profit, atmospheric pressure, precipitation, and cloud cover affect probability of departure from
breeding and wintering sites.

Results: We found that the probability of departure was related to changes in atmospheric pressure, almost completely
regardless of species, season, or location. Individuals were more likely to depart on nights when atmospheric
pressure had been rising over the past 24 h, which is predictive of fair weather over the next several days. By contrast,
wind profit, precipitation, and cloud cover were each only informative predictors of departure probability in a single

Conclusions: Our results suggest that individual birds actively use weather information to inform decision-making
regarding the initiation of departure from the breeding and wintering grounds. We propose that birds likely choose
which date to depart on migration in a hierarchical fashion with weather not influencing decision-making until after
the departure window has already been narrowed down by other ultimate and proximate factors.

Publication Date
May 1, 2023

Atmospheric pressure, Cloud cover, Departure probability, Migration, Precipitation, Weather, Wind profit,

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