Fear in urban landscapes: conspecific flock size drives escape decisions in tropical birds

Uncovering the Effects of COVID-19 Mask Wearing on Bird Flight Initiation Distance in Urbanized Areas in the Southern Philippines

The COVID-19 pandemic has caused significant changes in public and human activities worldwide, including using masks and reducing human interaction. These changes have also affected wildlife behavior, especially in urban areas. However, there is limited understanding of the impact of COVID-19-related human activities, mainly mask wearing, on the behavior of urban bird species. This case is intriguing in the Philippines, where COVID-19 restrictions and mask wearing have been more prolonged than in other countries. We studied two common urban bird species (Geopelia striata and Passer montanus) in Southcentral Mindanao, Philippines, to assess their response to mask wearing by examining their alert distance (AD) and flight initiation distance (FID). We found that birds had a reduced FID to mask wearing, but only significantly in G. striata (Zebra Doves) and not in P. montanus (Eurasian tree sparrow). The effect of the variables related to urbanization on FID was contrasting. For example, ambient noise increased bird vigilance while proximity to roads reduced bird FID in urbanized areas, but their effects were weaker compared to mask wearing. We conclude that mask wearing during the COVID-19 pandemic is a significant environmental element that alters bird escape responses in urban areas, and the effects may be species-specific.

Fear in urban landscapes: conspecific flock size drives escape decisions in tropical birds

Human-induced disturbances affect animal behaviours such as anti-predatory responses. Animals in urban environments tend to exhibit a reduced escape response, measured as a shorter flight initiation distance (FID), compared to their rural counterparts. While FID has been evaluated in animals dwelling in contrasting habitats (e.g. urban versus rural), little is known about how this response varies within urban environments, especially in tropical cities. Here, we studied the FID of 15 resident bird species in Bogota, Colombia, at 22 sites grouped into four categories (natural sites, metropolitan parks, zonal parks and residential areas) that differed in landscape features and evaluated which factors affected the escape responses of birds. We showed that birds foraging in larger flocks are more tolerant when being approached but they do not seem to be influenced by other factors such as heterospecific flock size, noise levels, pedestrian density, predator density, natural cover or body length. Also, birds inhabiting residential areas and parks showed a shorter FID compared to birds in natural areas suggesting that they are more tolerant of human-related disturbances compared to their conspecifics that live in natural areas within the city. Our study shows important differences in bird anti-predatory responses within the city and suggests that social strategies (i.e. flocking patterns) may be a mechanism for adapting to human-induced disturbances in urban tropical environments.