A1 Refereed original research article in a scientific journal
Demographic routes to variability and regulation in bird populations
Authors: Saether BE, Grotan V, Engen S, Coulson T, Grant PR, Visser ME, Brommer JE, Grant BR, Gustafsson L, Hatchwell BJ, Jerstad K, Karell P, Pietiainen H, Roulin A, Rostad OW, Weimerskirch H
Publisher: NATURE PUBLISHING GROUP
Publication year: 2016
Journal: Nature Communications
Journal name in source: NATURE COMMUNICATIONS
Journal acronym: NAT COMMUN
Article number: ARTN 12001
Volume: 7
Number of pages: 8
ISSN: 2041-1723
DOI: https://doi.org/10.1038/ncomms12001(external)
There is large interspecific variation in the magnitude of population fluctuations, even among closely related species. The factors generating this variation are not well understood, primarily because of the challenges of separating the relative impact of variation in population size from fluctuations in the environment. Here, we show using demographic data from 13 bird populations that magnitudes of fluctuations in population size are mainly driven by stochastic fluctuations in the environment. Regulation towards an equilibrium population size occurs through density-dependent mortality. At small population sizes, population dynamics are primarily driven by environment-driven variation in recruitment, whereas close to the carrying capacity K, variation in population growth is more strongly influenced by density-dependent mortality of both juveniles and adults. Our results provide evidence for the hypothesis proposed by Lack that population fluctuations in birds arise from temporal variation in the difference between density-independent recruitment and density-dependent mortality during the non-breeding season.
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