Causes and consequences of variation in incubation behaviour in the Canada jay (Perisoreus canadensis), a winter-nesting boreal passerine
Understanding of avian incubation is primarily gained from species nesting during spring and summer, under conditions markedly different from those prevailing in late winter. Using nest temperature loggers, we explored how ambient temperature and rainfall influenced off-bout frequency and off-bout duration and how incubation metrics influenced nest success of female Canada jays, a resident of boreal and subalpine forests that incubates eggs under sub-zero temperatures. Females spent 95.3 % ± 0.1 of their time incubating, and variation in attentiveness was driven primarily by variation in off-bout frequency than duration. Females took longer, less frequent off-bouts during warmer days and females that experienced high rainfall took shorter off-bouts. Nest success was negatively related to off-bout frequency but not duration. Our results suggest that attentiveness of females is driven by, and adjusted to, adverse conditions of late winter whereas low off-bout frequencies are driven by the need to avoid attracting nest predators.