The influence of ambient temperature on avian reproduction.

摘要

Ambient temperature exerts a strong influence on reproductive behavior and reproductive success in birds. I examined how variation in springtime temperature both among-years and within-years is related to variation in breeding initiation, productivity, and incubation behavior in a passerine species nesting in coniferous forest. I also examined how temperature and breeding initiation vary in populations of two species nesting in coniferous forests at different elevations. For the Mountain Chickadee (Poecile gambeli) breeding in nestboxes in three years, the year with the earliest increase in springtime temperatures (2004) was associated with the earliest mean egg laying initiation for the population. However, mean clutch size and mean nestling mass were the lowest in that same year. Within years, the relationship between pre-laying nestbox temperature and lay initiation date of individual pairs differed in each year (negative in 2005, positive in 2007). In both years, pairs with larger clutches had lighter nestlings but clutch size had no significant relationship to the proportion of eggs that survived to 14 days of age in either year. Male provisioning rate was higher at lower average nestbox temperatures in both years, but temperature explained only a modest portion of variation in male food delivery rate. The best model of female on-bout duration included temperature, provisioning rate and clutch size. The response to male provisioning depended on the length of time the female had invested in the current on-bout. The relationship between temperature and laying initiation date varied across years for populations of two passerine species (Mountain Chickadee and Dusky Flycatcher, Empidonax oberholseri) breeding in forests at different elevations. For both species in all forest types, lay initiation date and May temperatures were negatively associated. The most supported model for each species assumed that both the slopes and intercepts of the regressions of laying initiation date and temperature differed. Overall, these results are important for helping to predict how populations may respond to the immediate effects of temperature variation that could occur independent of long-term vegetation change should spring temperatures increase as projected under global climate change scenarios.