Interannual variation and long-term trends in proportions of resident individuals in partially migratory birds
Contributor(s)
University of Helsinki, Department of BiosciencesUniversity of Helsinki, Department of Environmental Sciences
University of Helsinki, Finnish Museum of Natural History
University of Helsinki, Finnish Museum of Natural History
Keywords
animal movementbird feeding
climate change
density-dependent strategy
fluctuating food availability
non-breeding habitat quality
range shift
wintering area
CLIMATE-CHANGE
AUTUMN MIGRATION
EUROPEAN BIRDS
POPULATION
FINLAND
REPRODUCTION
BEHAVIOR
1181 Ecology, evolutionary biology
animal movement
bird feeding
climate change
density-dependent strategy
fluctuating food availability
non-breeding habitat quality
range shift
wintering area
CLIMATE-CHANGE
AUTUMN MIGRATION
EUROPEAN BIRDS
POPULATION
FINLAND
REPRODUCTION
BEHAVIOR
1181 Ecology, evolutionary biology
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http://hdl.handle.net/10138/231228Abstract
Partial migration - a part of a population migrates and another part stays resident year-round on the breeding site - is probably the most common type of migration in the animal kingdom, yet it has only lately garnered more attention. Theoretical studies indicate that in partially migratory populations, the proportion of resident individuals (PoR) should increase in high latitudes in response to the warming climate, but empirical evidence exists for few species. We provide the first comprehensive overview of the environmental factors affecting PoR and the long-term trends in PoR by studying 27 common partially migratory bird species in Finland. The annual PoR values were calculated by dividing the winter bird abundance by the preceding breeding abundance. First, we analysed whether early-winter temperature, winter temperature year before or the abundance of tree seeds just before overwintering explains the interannual variation in PoR. Secondly, we analysed the trends in PoR between 1987 and 2011. Early-winter temperature explained the interannual variation in PoR in the waterbirds (waterfowl and gulls), most likely because the temperature affects the ice conditions and thereby the feeding opportunities for the waterbirds. In terrestrial species, the abundance of seeds was the best explanatory variable. Previous winter's temperature did not explain PoR in any species, and thus, we conclude that the variation in food availability caused the interannual variation in PoR. During the study period, PoR increased in waterbirds, but did not change in terrestrial birds. Partially migratory species living in physically contrasting habitats can differ in their annual and long-term population-level behavioural responses to warming climate, possibly because warm winter temperatures reduce ice cover and improve the feeding possibilities of waterbirds but do not directly regulate the food availability for terrestrial birds.Date
2016-03Type
ArticleIdentifier
oai:helda.helsinki.fi:10138/231228http://hdl.handle.net/10138/231228
0021-8790