Evaluation of mitigation translocation as a management tool to reduce conflicts between humans and American kestrels

Abstract

Raptor‐aircraft collisions (bird strikes) pose a serious safety risk to civil aircraft. Even smaller raptors, such as American kestrels (Falco sparverius), can be problematic within airport environments. Given widespread declines in kestrel populations, public interest, logistical and financial constraints, and other factors, managing kestrels at airports presents some unique challenges. I conducted a study to determine which biological (e.g., age and sex of the bird) and logistical factors (e.g., month and translocation distance) might influence the return of American kestrels live‐captured and translocated from 42 civil airports and military airbases within the contiguous USA during 2016–2021. American kestrels were live‐captured, banded, and translocated various distances from the airfields which were then monitored for returning kestrels. I developed a set of candidate generalized linear mixed models (binomial distribution) involving all possible subsets of 4 factors (age, sex, month, and distance translocated) as well as interactions, and used the location where a kestrel was live‐captured (i.e., airport) as a random factor in all mixed models. The return rate of American kestrels was very low (<4% of the individuals that were translocated). I found no evidence that the biological and logistical factors examined influenced return rates or the number of days it took returning birds to be resighted/recaptured. Management programs that use release sites 15 km from airfields would increase program efficacy and decrease implementation costs. There is no scientific information available regarding the efficacy of American kestrel management programs for reducing kestrel presence on airfields thus, these results provide a basis for informing such management decisions.