Breeding ecology of the common myna Acridotheres tristis : rural nestlings exhibit enhanced growth compared to urban conspecifics

Urbanization alters ecological conditions, yet its impacts on avian reproduction are not fully understood. In many bird species, nestlings growing up in cities tend to have slower growth rates and poorer body conditions than those in rural areas. Using nest boxes, we compared the breeding ecology and nestling growth of the common myna Acridotheres tristis in urban and rural environments of Mardan, Pakistan. Nest‐box occupancies were higher in rural areas, but both rural and urban nest boxes were rarely and unsuccessfully reused for the second breeding attempt. Fledging success was closely related to box orientation, and east‐facing boxes had the greatest number of fledglings in both habitats. Nest architecture within the boxes differed considerably, with nest construction taking longer at urban sites than at rural sites. Urban nests were heavier, with smaller outer diameters but slightly larger inner diameters, whereas nest depth did not differ between habitats. Urban nests contained anthropogenic materials (plastic) and feathers, whereas rural nests primarily contained natural plant materials. Urban pairs began breeding earlier than their rural counterparts; however, rural nests had longer incubation and nestling periods, resulting in extended overall breeding timelines. Clutch and brood sizes did not vary between habitats, although urban eggs were smaller, narrower, and more elongated. Fledging success was significantly higher in urban nest boxes than in rural nest boxes. Most importantly, urban fledglings had compromised growth trajectories and poorer body conditions, indicating physiological and developmental costs of growing up in a city. Our results suggest that common mynas in anthropogenic habitats show wide variations in the timing of breeding and the growth trajectory of nestlings. These results enhance our understanding of avian life‐history plasticity in the face of rapid urbanization and offer a broad perspective on the evolutionary ecology of urban bird adaptation.