Multiple ecological and sociobiological processes drive the coordination of timing of reproduction for a wide array of species (Lack, 1968;Perrins, 1970). Matching reproductive activities with optimal environmental conditions is crucial to optimize reproductive success (Ims, 1990a). As such, temporal clustering of reproductively active individuals is typically driven by climatic seasonality (Ims, 1990a), especially when breeding seasons are restricted to shorter temporal periods (Emlen & Demong,