Effects of climate variation on bird escape distances modulate community responses to global change

Climate and land use are rapidly changing environmental conditions. Behavioral responses to such global perturbations can be used to incorporate interspecific interactions into predictive models of population responses to global change. Flight initiation distance (FID) reflects antipredator behaviour defined as the distance at which an individual takes flight when approached by a human, under standardized conditions. This behavioural trait results from a balance between disturbance, predation risk, food availability and physiological needs, and it is related to geographical range and population trends in European birds. Using 32,145 records of flight initiation distances for 229 bird species during 2006-2019 in 24 European localities, we show that FIDs decreased with increasing temperature and precipitation, as expected if foraging success decreased under warm and humid conditions. Trends were further altered by latitude, urbanisation and body mass, as expected if climate effects on FIDs were mediated by food abundance and need, differing according to position in food webs, supporting foraging models. This provides evidence for a role of behavioural responses within food webs on how bird populations and communities are affected by global change.

Automated summary

Climate and land use changes are affecting bird populations' behavior and flight initiation distance (FID) in response to human approaches. FIDs decrease with increasing temperature and precipitation, indicating reduced foraging success in warm and humid conditions. Factors like latitude, urbanization, and body mass also influence FID trends, suggesting that climate effects on FIDs are mediated by food availability and hierarchical positions in food webs. This study highlights the importance of behavioral responses within food webs in influencing bird populations and communities under global change.