Abstract
How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal.
Highlights
A central ecological topic is to quantify extrinsic and intrinsic factors behind population growth rate
The climate window analyses identified three climate windows during the preceding non-breeding season that appeared to be associated with population growth rate: winter temperature in the Mediterranean region, precipitation in Africa during the previous autumn, and spring precipitation in Europe (January–April)
We examined in two different steps how climatic factors along different parts of the annual cycle and migratory route affect population growth rate in a long-distance migrant, the pied flycatcher
Summary
A central ecological topic is to quantify extrinsic (e.g. weather conditions) and intrinsic (e.g. population density and breeding success) factors behind population growth rate. Conditions in non-breeding areas and along migratory route directly affect individual survival but may have carry-over effects on breeding success via condition and timing of reproduction (Webster et al 2002; Norris and Taylor 2006; Sæther et al 2006; van de Pol et al 2010; Rushing et al 2017). Whether it is the breeding, nonbreeding, or migration phase that most affect the population. Adverse weather conditions along the migratory route may delay arrival and decrease survival during migration with potential adverse effects on population size (Hüppop and Winkel 2006; Møller et al 2008; Sillett and Holmes 2002; Klaassen et al 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
