Abstract

Climate change will select for adaptations to warmer conditions, including increased size of exposed body parts (Allen’s rule). In birds, the bill and legs appear to help regulate heat loss.  Plasticity in growth with higher developmental temperatures could buy time for more profound genetic change. Our study asks if nestling American crows (Corvus brachyrhynchos), a widespread North American species, develop different bill and leg morphology in relation to temperatures experienced during the nestling period.  Using a data set of bill, tarsus and weight measures of  >2300 nestlings over 30 years in Ithaca, NY, plus weather data from a nearby station,  we tested the prediction that bill and tarsus will be relatively larger in nestlings experiencing higher temperatures during development. Initial results suggested that bill surface area relative to mass grew larger when temperatures were high. We report further results on leg and bill morphology with an expanded data set.