When the going gets tough, the dove gets going: feral pigeons maintain nest attendance rates during food shortages with asymmetrical biparental care

Abstract Reproduction is an important but costly life history stage, and birds may share this cooperatively through biparental care. However, parental efforts are not always shared equally, with many bird species exhibiting asymmetrical biparental care. In feral pigeons (Columba livia) both sexes incubate the eggs, although males (the ‘helper’) do so far less than females (the primary parent). We conducted a supplementary feeding study in food-scarce environments to understand how food availability affects energy constraints and incubation effort in breeding pigeons. We found responses to food availability to differ between sexes. Supplementary feeding was associated with mass gain in incubating females but not males. This suggests primary parents were more energetically constrained than helper parents when incubating eggs. Daily incubation time in females was 6% longer when fed, while this was 5% lower in males. Overall nest attendance (98%) and nest activity remained unchanged regardless of food availability. These suggest that in species with asymmetrical biparental care, helper parents, which invest less time incubating relative to the primary parent, can compensate for reduced nest attention by the latter during food shortages (i.e. longer foraging trips). In doing so, parents cooperatively buffer offspring from acute environmental variability without sacrificing parental care.