Lockdown effects on fear: direct and indirect effects mediated by release of urban predators

Abstract

The Covid-19 lockdown reduced drastically human presence outdoors, providing an uncontrolled experiment for disentangling direct and indirect effects of human presence on animal fearfulness. We measured 18,494 flight initiation distances (FIDs, the distance at which individual animals fly away when approached by a human) from 1,333 populations of 202 bird species taken in four European cities both before, during and after the lockdown. Differential responses to lockdown among urban and rural habitats and between signing and non-singing birds showed that lockdown relaxed direct disturbance effects on birds in rural habitats, but increased indirect fear effects mediated by predator release (mainly feral cats) in cities.

Urban birds become less fearful following COVID-19 reopenings

“…It could be that urban colonists from non-urban origins might have a lower baseline fear response in comparison to the non-urban population at large, and potentially decrease their fear response with human activity. We note, that in contrast to virtually all other studies of anthropause effects in birds (e.g., 1,3,4,[28][29][30] ) that used unmarked birds and were unable to focus on individuals, these insights emerged only from a detailed, longitudinal study of individuals.…”

“…Collectively, our results suggest that changes in fear responses might not be as predictable as we might expect, and likely depends on which individuals and how their behaviors develop and shift in combination with strong and rapidly shifting collective human behaviors. Only through studies on individual animals tracked over time can we understand the mechanisms underlying population response, which cannot be confirmed from contradictory broadscale patterns found in metanalyses 28,30 . While the anthropause created much human hardship, it offered a unique opportunity to identify an important new avenue of ontogenetic research that can create insights which will help us better conserve biodiversity in a rapidly changing, human-dominated world.…”