Diurnal patterns of ambient temperature but not precipitation influence incubation behavior in Great Tits

Abstract

Environmental conditions affect incubation behavior, but whilst the effect of ambient temperature is studied and still controversially discussed, the role of precipitation is unknown. Here, we analyzed the effect of local ambient temperature and precipitation on incubation behavior of female Great Tits (Parus major) and accounted for diurnal patterns of weather conditions. We monitored the incubation behavior of females using temperature data loggers, thus identifying periods of staying inside nest boxes incubating, and leaving nest boxes (off-bout). In total, 685 single off-bouts were analyzed between the first 8 days of incubation directly after clutches were completed. Our study showed that whilst precipitation had no effect on incubation behavior, number and duration of off-bouts were negatively related to ambient temperature, which varied throughout the day. We showed that females took longer off-bouts during low-temperature early mornings, which may result from the need to forage after fasting during the night. Thus, foraging in the early morning seemed to outcompete energy requirements during these cold temperature periods. In addition, females spent less time off the nest as incubation progressed. Our results emphasize that patterns of incubation behavior cannot be understood without taking into account varying temperature conditions throughout the day.