Differences in flight initiation distances between African and Australian birds

Abstract

Associations between escape behaviours of birds approached by humans and life history traits differ between continents. This suggests environment and history have shaped the evolution of escape at the continental scale. We compared the escape behaviour of birds between eastern Australia (relatively low density and shorter history of human presence) and eastern Africa (high density and substantially longer history of human presence), in relation to life and natural history traits known to influence escape behaviour. We examined associations between flight initiation distance (FID) and life and natural history variables, using phylogenetically controlled analysis and model selection procedures, for 9372 FIDs from 516 bird species. Overall, African birds had shorter FIDs than Australian birds; however, this difference was only observed among nonmigratory (resident) species. Migratory birds showed no continental level differences in FIDs. Across continents, birds in ‘wetland’ and ‘treed’ habitats both had significantly longer FIDs than birds in ‘scrub’ habitats. Diet and social traits (cooperative breeding and flocking) did not significantly influence FID. The relationship between body mass and FID was positive for Australian birds but not so for African birds. This study (1) suggests that resident eastern African birds are more tolerant of humans and (2) supports the contention that some principles regarding escape behaviour of birds might represent universal patterns (e.g. longer FIDs in open wetland habitats), others (e.g. longer FIDs in larger birds) vary geographically or with habituation, perhaps in relation to the history of cohabitation between humans (and other predators) and birds.