Variation in forest area influences post‐fledging development and dispersal onset in the Eurasian Goshawk ( <i>Astur gentilis</i> )

Natal dispersal is a key ecological process influencing gene flow, population connectivity and individual fitness. In altricial birds, the transition from fledging to natal dispersal is mediated by the post‐fledging dependence period, which is often difficult to observe in elusive, forest‐dwelling species. We used GPS telemetry to track 35 juvenile Eurasian Goshawks ( Astur gentilis ) in Scotland to examine how age, sex and habitat structure within the natal territory and surrounding landscape affected their post‐fledging development and, hence, the onset of natal dispersal. The onset of dispersal was determined using spatial and temporal thresholds, which were applied to identify key changes in mobility. The age at dispersal ranged from 60 to 95 days. The development period, defined as the time between first detectable movement and dispersal onset, varied considerably among individuals, ranging from 2 to 37 days. The older an individual was at the first detectable movement, the shorter the development period, suggesting that physical development constrained dispersal onset. Females dispersed approximately 4 days later than males, consistent with raptors' reversed sexual size dimorphism. Notably, the development period was shorter in natal territories with greater forest area and when there was a greater ratio of forest in the wider environment relative to the natal territory. Forest fragmentation may therefore delay dispersal onset, potentially through reduced food availability hindering physical development, or due to juveniles' reluctance to traverse more open habitats. Our results highlight the influence of habitat structure on Goshawk development and dispersal timing, with implications for forestry management and conservation planning.