Fitness consequences of male provisioning of incubating females in a desert passerine bird

Male provisioning of incubating females can increase reproductive success by maintaining physiological condition of females and consistency of incubation. The effects of male provisioning on the maintenance of incubation temperature and embryo development should be particularly pronounced in environments where ambient temperature exceeds the tolerance of unincubated eggs and where consistency of female incubation might be particularly important for hatching success. Here, we investigated the reproductive consequences of incubation feeding in a desert population of House Finches (Carpodacus mexicanus) in southwestern Arizona. We found that greater nest attentiveness by females was related to higher minimum incubation nest temperature, that in turn was closely associated with hatching success. Only 44% of males regularly provisioned their incubating females. Although provisioned females maintained higher incubation temperature and took fewer incubation breaks than non-provisioned females, overall, male provisioning did not influence incubation dynamics or hatching success. Further, a male's incubation feeding rate did not correlate with male provisioning of nestlings. These results corroborate the finding that, in male House Finches, neither provisioning of incubating females nor pre-incubation courtship feeding are associated with increases in circulating pituitary prolactin--the hormone regulating male provisioning of nestlings. We suggest that incubation provisioning by male might be a component of pair maintenance behavior and that variation in male incubation behavior is best understood in relation to asymmetries in residual reproductive values between the mates.