Division of labor:: Incubation and biparental care in house sparrows (Passer domesticus)

In the great majority of animal taxa, males do not participate in parental care, but substantial paternal care is common across avian species. We examined male and female incubation contributions in House Sparrows (Passer domesticus), quantifying the incubation behavior of free-living, individually color-banded parents during 47 nesting cycles. We also measured the relative warmth of male and female incubation surfaces. Females spent more time incubating than their male partners, and female time incubating served as the best single predictor for hatching success. Considered alone, male time incubating correlated negatively with hatching success, but that effect was nullified when female incubation was taken into account. Females had warmer abdomens than males, a difference that may reflect greater development of brood patch and effectiveness of incubation in that sex. Here, male badge size was not demonstrably associated with either male or female incubation patterns or hatching success.