Adjusting trail cameras to improve monitoring of small open cup nesting birds

Abstract

Camera traps are a valuable tool in wildlife monitoring. Despite their wide use to capture large or medium-sized species, modern techniques also allow them to capture small animals. However, customized cameras, which meet the challenging demands for this purpose during fieldwork, are still quite expensive and require a certain technical know-how. Here we present a way to modify commercial trail cameras to monitor open-nesting songbirds. In particular, we describe how to adjust focus and exposure in order to capture close-up situations of small animals which are very distinct from the default settings when capturing large wildlife. We illustrate the applicability of the modifications from data of a nest predation survey in the Blackcap (Sylvia atricapilla). Compared to pictures from a preliminary study using unmodified trail cameras of the same kind, the pictures were much improved in picture focus and in nocturnal exposure. In addition to improved species identification, the modifications also allowed the cameras to capture more details of life-history events (e.g. of hatching processes and feeding). The manipulation protocol offers a promising and cost-effective approach for nest monitoring as well as for different areas of “close-up” applications to study small endothermic animals.