Habitat loss, not fragmentation, drives occurrence patterns of Canada lynx at the southern range periphery.
Peripheral populations often experience more extreme environmental conditions than those in the centre of a species' range. Such extreme conditions include habitat loss, defined as a reduction in the amount of suitable habitat, as well as habitat fragmentation, which involves the breaking apart of habitat independent of habitat loss. The 'threshold hypothesis' predicts that organisms will be more affected by habitat fragmentation when the amount of habitat on the landscape is scarce (i.e., less than 30%) than when habitat is abundant, implying that habitat fragmentation may compound habitat loss through changes in patch size and configuration. Alternatively, the 'flexibility hypothesis' predicts that individuals may respond to increased habitat disturbance by altering their selection patterns and thereby reducing sensitivity to habitat loss and fragmentation. While the range of Canada lynx (Lynx canadensis) has contracted during recent decades, the relative importance of habitat loss and habitat fragmentation on this phenomenon is poorly understood. We used a habitat suitability model for lynx to identify suitable land cover in Ontario, and contrasted occupancy patterns across landscapes differing in cover, to test the 'threshold hypothesis' and 'flexibility hypothesis'. When suitable land cover was widely available, lynx avoided areas with less than 30% habitat and were unaffected by habitat fragmentation. However, on landscapes with minimal suitable land cover, lynx occurrence was not related to either habitat loss or habitat fragmentation, indicating support for the 'flexibility hypothesis'. We conclude that lynx are broadly affected by habitat loss, and not specifically by habitat fragmentation, although occurrence patterns are flexible and dependent on landscape condition. We suggest that lynx may alter their habitat selection patterns depending on local conditions, thereby reducing their sensitivity to anthropogenically-driven habitat alteration.
Environmental and Life Sciences, Trent University, Peterborough, Canada.
Megan L
ML
Hornseth
Wildlife Research & Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Peterborough, Canada.
Aaron A
AA
Walpole
Regional Operations Division, Ontario Ministry of Natural Resources, South Porcupine, Canada.
Lyle R
LR
Walton
Wildlife Research & Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Peterborough, Canada.
Jeff
J
Bowman
Wildlife Conservation Society Canada, Toronto, Canada.
Justina C
JC
Ray
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.
Marie-Josée
MJ
Fortin
Department of Biology, Trent University, Peterborough, Canada.
Dennis L
DL
Murray
D000818:Animals; D002170:Canada; D017753:Ecosystem; D004777:Environment; D046008:Lynx / Q000502:physiology*; D008962:Models, Theoretical; D011156:Population Density; D011157:Population Dynamics