Supplementary material for: "Who gets the pole position? Spatial and social behaviour of snowfinches at winter feeders in Alpine habitat"

Abstract

In collective foraging, an individual’s ability to compete with conspecifics can considerably influence its foraging strategy and success. Strong competitors can fight for prioritised access to food, while weak competitors may avoid aggressions and rather seek out less contested foraging opportunities. However, insecure access to food can be detrimental to weak competitors, especially during periods of low and unpredictable resource availability. Here we investigated individual foraging behaviour of White-winged snowfinches Montifringilla nivalis, specialists of alpine habitats and their strategies for coping with competition for food resources in winter. A difference in condition dependence of survival rates between males and females in this species has made us hypothesise that males may be more dominant in accessing food resources than females. We set up artificial experimental food patches in the Swiss Alps to observe foraging male and female snow finches and recorded their behaviour in interactions with conspecifics and their spatial position relative to the food. We found that individuals frequently occupying positions close to the food resources were more involved in agonistic interactions than individuals staying in more distant positions. This result suggests that different individuals use different foraging strategies, probably depending on their level of competitiveness. Furthermore, we observed males to forage slightly closer to the food source than females, which could imply that females may have less access to artificial feeders than males.