# Living on the Edge: Juvenile Foraging and Adult Breeding Ecology of an Aerial Top Predator in Urban Environments

## TL;DR

This study explores how urban environments support Common Buzzards, revealing their use of residential areas for foraging and breeding, and the risks posed by rodenticides.

## Contribution

The study provides new insights into the foraging and breeding ecology of raptors in urban settings using GPS tracking and nest monitoring data.

## Key findings

- Common Buzzards utilize residential open areas like courtyards for foraging in urban Berlin.
- Urban green spaces such as parks and cemeteries serve as suitable breeding habitats for the species.
- Rats are a prevalent prey in urban foraging areas, but anticoagulant rodenticides pose a poisoning risk.

## Abstract

Urbanization is irreversibly transforming natural ecosystems globally, yet we still lack a holistic understanding of the challenges and opportunities that urban environments present to wildlife. To investigate how raptors utilize urban landscapes, we analyzed 4 years of GPS tracking data of 22 juveniles collected during natal dispersal, combined with 7 years of nest‐monitoring data from an urban population of the Common Buzzard (
Buteo buteo
), an opportunistic rodent specialist, in Berlin (Germany). Our goals were threefold: (a) to estimate core foraging ranges (CFRs), (b) to characterize small‐scale temporal foraging areas (TFAs) within these ranges, and (c) to model the breeding habitat suitability based on environmental predictors. CFRs were distributed across the city, with a mean area of 11.0 km2 (±13.9 sd). TFAs within these ranges had a mean area of 0.2 km2 (±0.3) and were occupied over a mean time span of 274 days (±198). TFAs were mostly located in residential open areas (e.g., courtyards) and were characterized by decreasing area and shorter occupation duration with increasing human population density. Urban TFAs showed a high prevalence of rats (
Rattus norvegicus
). Active pest control measures were observed at most TFAs, particularly in residential areas. We mapped a total of 17.3 km2 of suitable breeding habitat within the study area (217 km2) and 45.4 km2 when projected across the city region (890 km2). Suitable breeding habitat consisted of isolated patches, i.e., single courtyards in residential areas, and a network of urban green spaces, e.g., city parks and cemeteries. Cities can provide profitable foraging and breeding conditions for raptors, with abundant prey in proximity to suitable breeding sites. The study improves our understanding of how raptors utilize the urban city landscape and underlines the importance of urban green spaces as a basis for the protection and conservation of urban wildlife.

We analyzed a combination of GPS tracking data and nest‐monitoring data from an urban population of an opportunistic rodent specialist, the Common Buzzard (
Buteo buteo
), to analyze how raptors utilize urban landscapes. Buzzards occupied even extreme habitats such as residential areas for foraging and breeding and benefit from lucrative foraging conditions, abundant prey and mature tree stands. The advantages may be counteracted by the risk of poisoning with anticoagulant rodenticides used for pest control, thus underlining the thin line between chances and risks for urban wildlife in cities.