Fitness and fur colouration - testing the camouflage and thermoregulation hypotheses in an Arctic mammal

1. Selection for crypsis has been recognised as an important ecological driver of animal coloration, whereas the relative importance of thermoregulation is more contentious with mixed empirical support. A potential thermal advantage of darker individuals has been observed in a wide range of animal species. Arctic animals that exhibit colour polymorphisms and undergo seasonal colour moults are interesting study subjects for testing the two alternative hypotheses: demographic performance of different colour morphs might be differentially affected by snow cover with a cryptic advantage for lighter morphs, or conversely by winter temperature with a thermal advantage for darker morphs. 

2. In this study, we explored whether camouflage and thermoregulation might explain differences in reproduction and survival between the white and blue colour morphs of the Arctic fox (Vulpes lagopus) under natural conditions.

3. Juvenile and adult survival, breeding propensity, and litter size were mea...