Urban birds become less fearful following COVID-19 reopenings

Abstract

Following the COVID-19 pandemic, many people around the world stayed home, drastically altering human activity in cities. This exceptional moment provided researchers the opportunity to test how urban animals respond to human disturbance, in some cases testing fundamental questions on the mechanistic impact of urban behaviors on animal behavior. However, at the end of this "anthropause," human activity returned to cities. How might each of these strong shifts affect wildlife in the short and long term? We focused on fear response, a trait essential to tolerating urban life. We measured flight initiation distance--at both individual and population-levels--for an urban bird before, during, and after the anthropause to examine if birds experienced longer-term changes after a year of lowered human presence. Dark-eyed juncos did not change fear levels during the anthropause, but they became drastically less fearful afterwards. These surprising and counter-intuitive findings, made possible by following the behavior of individuals over time, has led to a novel understanding that fear response can be driven by plasticity, yet not habituation-like processes. The pandemic-caused changes in human activity have shown that there is great complexity in how humans modify a behavioral trait fundamental to urban tolerance in animals.