Bed sites as thermal refuges for a cold‐adapted ungulate in summer

Ungulates that are adapted to cold climates may use bed sites as thermal refuges during summer. At the southern edge of their distribution moose Alces alces often encounter ambient summer temperatures above their upper critical temperature. Summer is also when moose increase food consumption and metabolism, which increases heat generation that must typically be lost at bed sites. To determine if moose use bed sites that enable heat loss when temperatures are hot, we randomly sampled bed sites of moose from across the entire range of ambient summer temperatures. We calculated kernel density estimates for each day and night using GPS locations collected each 20 min for an entire summer to identify bed sites. Kernel density estimates identified bed sites accurately. During the day, moose bedded under lowland forest canopies where substrates had high water content. At night, bed sites were in openings which are associated with greater browse availability and net heat loss. Lowland forests interspersed with openings should help moose to maintain thermal balance during summer. Because thermoregulatory behavior is linked with fitness, thermal refuges should be especially important in areas where moose population declines have been positively correlated with warming temperatures.