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.
Prey monitor surrounding dangers independently or cooperatively (synchronized and coordinated vigilance), with independent and synchronized scanning being prevalent. Coordinated vigilance, including unique sentinel behaviour, is rare in nature, since it is time-consuming and benefit-limited. Evidence does not indicate animals adopting alternative vigilance strategies during antipredation scanning. Considering the cooperative nature of both synchronization and coordination, we assessed whether group members could keep alert synchronously or coordinatedly under different circumstances, determining whether cooperative vigilance is context dependent. Under the framework of conservation behavior, we studied how human behaviour and species-specific variables impacted individual and collective vigilance of globally threatened Black-necked Cranes (Grus nigricollis) and explored behaviour-based wildlife management. We tested both predation risk (juveniles in group) and human disturbance (level and distance) effects on individual and collective antipredation vigilance of black-necked crane families. Adults spent significantly more time (proportion and duration) on scanning than juveniles, and parents with juveniles behaved more vigilant. Observer distance affected individual vigilance of adults while juveniles were influenced by none of these variables. With the number of juveniles and disturbance increased, crane couples decreased synchronization of vigilance and they shifted to coordination, which has so far never been reported yet. Similarly, with observer approaching, adults shift vigilance from synchronization to coordination. The collective vigilance shift from synchronization to coordination as a function of observer distance could help us determining a safe distance of c. 400m for the most vulnerable family groups with two juveniles, so as no obvious interference with the threatened birds by human proximity. We argue that vigilance behaviour could be a reliable indicator in future nature-based tourist management and decision-making, which can be derived from conservation solutions in nature.