Search for a command to run...
Abstract Current rates of urbanization are unprecedented and wildlife must adapt or face population declines. Falco sparverius (American Kestrel) inhabit urban areas; however, whether human-dominated landscapes impact their space-use, survival, and reproductive success is largely unknown. We monitored F. sparverius nest boxes along a gradient of urbanization, measured using impervious surface area (ISA), and deployed 108 GPS loggers on breeding adults to examine the relationship between urbanization, home range size, and adult and nestling health during the 2021–2023 breeding seasons. Male home ranges (n = 29) were 9.14 times larger than those of females (n = 44), and home range sizes decreased as ISA increased for both sexes. Adult females lost weight at twice the rate of adult males; and, although there was no relationship between weight loss and home range size, females lost more weight as ISA increased. The effect of female home range size on individual nestling weight and the weight variation within broods depended on ISA. In less urbanized areas, larger home ranges led to higher nestling weight and lower within-brood weight variation, but this relationship was reversed in more urbanized areas, where larger home ranges led to lower nestling weight and higher variation compared to smaller home ranges with similar ISA. Male home range size did not explain nestling weight but showed a similar, dependent effect on within-brood weight variation as the female home range size. Results suggest that smaller home range sizes in urban areas may be adaptive for F. sparverius. However, the effects of urbanization on adult female weight loss shows that while they can successfully breed in urban areas, it could come at a cost to female health and potentially survival. Falco sparverius may be more sensitive to urbanization than previously reported.