An assessment of the effectiveness of walk-in traps to capture a Neotropical raptor, the Chimango Caracara (Milvago chimango), across different environments

Abstract

Many raptor studies require the capture of individuals and selection of the most effective trapping techniques may be crucial to achieving research goals. We assessed the effectiveness of walk-in traps to capture a very common, but poorly studied Neotropical raptor bird, the Chimango Caracara (Milvago chimango) in different environments and we evaluated the effects of environmental and methodological variables on trapping success and number of individuals captured. During 2009–2013 we captured a total of 1452 individuals (188 days and 2178 hours of effective trapping) with at least 423 birds being recaptured at least once during the study. The mean daily capture rate was 0.90 ind/h, with a maximum of 11 ind/h. Number of individuals captured and trapping success were higher during the breeding season and in larger colonies but were lower when longer lapse of non-trapping periods were recorded, then these variables were independent of any other methodological factor and environment type. Trapping success, but not number of individuals captured, increased during the morning when compared with afternoon hours. Trapping success and number of individuals captured were not biased towards any sex, or age group. Our results show that the walk-in trap is a useful and highly effective trapping technique for the Chimango Caracara measured both in terms of number of captures and trapping success throughout the year.