Annual schedules reflect an evolved balance of survival and reproduction. Seasonality of food in the temperate zone is a strong selective force underlying scheduling in birds, and release from this through exploitation of non-seasonal food is presumed to have led to opportunistic breeding. Red crossbills (Loxia curvirostra) feed on conifer seeds that can persist through an entire annual cycle and are highly flexible in that they can often breed in the north-temperate winter. Prior research on one crossbill ecotype suggests that, despite this flexibility, crossbills remain seasonal in some important aspects of their reproductive physiology. Further, different ecotypes that forage on different conifers– including some that produce more stable seed crops – may display different temporal patterns of breeding in the wild. Here we show that while four different eco-types of red crossbill demonstrate some quantitative variation in winter breeding activity, they all exhibit clear bi-modal and highly seasonal breeding patterns. We discuss these results in the context of photoperiod, temperature and food to examine selective pressures on the evolution of opportunism in the temperate zone.