The paper extends our previous research on plasticity in the timing of coat color molts to a second study site which differed dramatically in climate and day length (= photoperiod). We compared the timing at the two sites and jointly tested the effects of variables influencing the molt timing. We confirmed our previous finding that hares initiate both the spring and fall molts at the same time each year, consistent with a photoperiod modulator of timing. Next, we confirmed that hares exhibit some ability to adjust the rate of the spring white-to-brown molt to the immediate snow conditions.
Finally, we investigated, for the first time in any mammal species, whether hares modify their anti-predatory behaviors (hiding, fleeing, or micro-site selection) in a manner that reduces camouflage mismatch. We found that hares do not hide more in vegetation or do not increase the distance at which they flee from predators when color mismatched against their background. Additionally, hares do not select their hiding spots with background color that matches their coat color. Conversely, they prefer spots with relatively little snow which in turn increases camouflage mismatch.
Based on those findings, we concluded that the current levels in phenotypic plasticity are insufficient to facilitate adaptation to camouflage mismatch and any future adaptation to climate change will require natural selection on the molt timing or on hare behavior.
– by Marketa Zimova