Bird flight initiation distances in relation to distance from human settlements in a Tanzanian floodplain habitat

Abstract

Human activity affects wildlife in many ways, but there have been few studies of how wildlife behavioural responses to human disturbance vary with distance from centres of human activity. Theory suggests that fear responses may be either higher in areas with high disturbance (disturbance avoidance) or lower in such areas (e.g. due to habituation). We used flight initiation distance (FID) to study how fear responses of 16 bird species varied with distance from villages (range 0.1–11.6 km) within the Ramsar site of Kilombero Valley, Tanzania. A linear model indicated that FID was not related to distance from villages, but varied between habitats. However, a piecewise linear model (linear response up to 2 km, flat response >2 km from villages) provided a better fit and suggested that there may be a small decrease in FID close to human settlements, in particular for the Common Bulbul (Pycnonotus barbatus) and a few other species, although the majority of species still showed little change in FID with distance from human settlements. Our results suggest that a few species may respond to human disturbance with a decreased FID, whereas the majority of species showed little variation in FID in relation to distance from human settlements, and may therefore be negatively affected by increasing frequency of human disturbance.