Intraspecific variation in incubation behaviors along a latitudinal gradient is driven by nest microclimate and selection on neonate quality

The strategies by which animals allocate reproductive effort across their lifetimes vary, and the causes of variation in those strategies are actively debated. In birds, most research has focused heavily on variation in clutch size and fecundity, but incubation behavior and other functionally related traits have received less attention. Variation in incubation period duration is notable because time-dependent sources of clutch mortality should impose strong directional selection to minimize the incubation period. However, life-history theory predicts multiple mechanisms by which inter- and intraspecific variation in incubation behaviors may be adaptive.

We conducted one of the first studies of intraspecific latitudinal variation in avian incubation behaviors across a large portion of a single species’ range. We used motion-activated nest cameras inside Burrowing Owl nests at 5 study sites to quantify variation in daily nest attentiveness, cumulative nest attendance, and incubation pe...