Avian frugivory rates at an abundant tree species are constant throughout the day and slightly influenced by weather conditions

Abstract

Birds, like most animals, are expected to adjust their foraging activity in response to biotic and abiotic variations to optimize energy intake and reduce costs associated with finding and ingesting food. This may lead to temporal variation in the exploitation of food resources, which has been investigated for birds of different feeding guilds but remains poorly understood for frugivorous species. Here, we tested whether the frugivory activity of birds on Schinus terebinthifolia trees varies throughout the day during the austral autumn and winter and whether variation is related to weather conditions. For two consecutive years, we quantified frugivory events for 304 h in 19 individuals of S. terebinthifolia observed across four time periods throughout the day. We found that the number of frugivory events was similar irrespective of the time period, both for the entire assemblage (all species pooled together) and for the most common species analyzed individually. We additionally found that frugivory activity was slightly influenced by temperature and wind. The lack of any effect of daytime period on fruit consumption may relate to the high and prolonged levels of fruit availability in S. terebinthifolia and the short photoperiod of the autumn–winter, which favors frequent feeding throughout the day. Such constant removal of fruits by a diverse assemblage of generalist fruit consumers probably enhances seed dispersal and may have important implications for the population dynamics of this abundant plant. Our results also demonstrate that data on avian frugivory in temperate, open-vegetation environments can be quantified throughout the entire daytime during the cold season without temporal bias, which has important methodological implications for studies on bird–plant interactions.