Predictors of contraction and expansion of area of occupancy for British birds.
Geographical range dynamics are driven by the joint effects of abiotic factors, human ecosystem modifications, biotic interactions and the intrinsic organismal responses to these. However, the relative contribution of each component remains largely unknown. Here, we compare the contribution of life-history attributes, broad-scale gradients in climate and geographical context of species' historical ranges, as predictors of recent changes in area of occupancy for 116 terrestrial British breeding birds (74 contractors, 42 expanders) between the early 1970s and late 1990 s. Regional threat classifications demonstrated that the species of highest conservation concern showed both the largest contractions and the smallest expansions. Species responded differently to climate depending on geographical distribution-northern species changed their area of occupancy (expansion or contraction) more in warmer and drier regions, whereas southern species changed more in colder and wetter environments. Species with slow life history (larger body size) tended to have a lower probability of changing their area of occupancy than species with faster life history, whereas species with greater natal dispersal capacity resisted contraction and, counterintuitively, expansion. Higher geographical fragmentation of species' range also increased expansion probability, possibly indicating a release from a previously limiting condition, for example through agricultural abandonment since the 1970s. After accounting statistically for the complexity and nonlinearity of the data, our results demonstrate two key aspects of changing area of occupancy for British birds: (i) climate is the dominant driver of change, but direction of effect depends on geographical context, and (ii) all of our predictors generally had a similar effect regardless of the direction of the change (contraction versus expansion). Although we caution applying results from Britain's highly modified and well-studied bird community to other biogeographic regions, our results do indicate that a species' propensity to change area of occupancy over decadal scales can be explained partially by a combination of simple allometric predictors of life-history pace, average climate conditions and geographical context.
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia corey.bradshaw@adelaide.edu.au.
Corey J A
CJ
Bradshaw
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Barry W
BW
Brook
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Steven
S
Delean
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Damien A
DA
Fordham
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), C/José Gutierrez Abascal, 2, Madrid 28006, Spain.
Salvador
S
Herrando-Pérez
The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Phillip
P
Cassey
Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), C/José Gutierrez Abascal, 2, Madrid 28006, Spain Centre for Ecology and Conservation Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Treliever Road, Penryn, Cornwall TR10 9FE, UK InBio/CIBIO, University of Évora, Largo dos Colegiais, Évora 7000, Portugal.
Regan
R
Early
Department of Biology, University of Utah, 257 S. 1400 E. Rm 201, Salt Lake City, UT 84112, USA KuzeyDoga Dernegi, Ortakapı Mah. Şehit Yusuf Cad, No: 93/1, Kars 36100, Turkey.
Cagan H
CH
Sekercioglu
Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), C/José Gutierrez Abascal, 2, Madrid 28006, Spain InBio/CIBIO, University of Évora, Largo dos Colegiais, Évora 7000, Portugal Imperial College London, Silwood Park Campus, Buckhurst Road Ascot, Berkshire SL5 7PY, UK.
Miguel B
MB
Araújo
D063147:Animal Distribution; D000818:Animals; D001717:Birds / Q000502:physiology*; D057231:Climate Change; D004777:Environment; D005843:Geography; D011157:Population Dynamics; D012621:Seasons; D006113:United Kingdom
biogeography; body size; climate; demography; dispersal; threatened species