An Aquatic Bal-Chatri for Trapping Snail Kites (Rostrhamus sociabilis)

Abstract

The endangered Rostrhamus sociabilis plumbeus (Florida Snail Kite) has been the focus of several ecological studies emphasizing movements between and within wetland fragments. These studies have required the ability to trap and radiotag free-flying adults without significant risk of injury. We developed and tested a safe alternative to previous methods for trapping Snail Kites as part of a comparative study of VHF and satellite telemetry. The aquatic bal-chatri borrows from historical trap designs with modifications for trapping aquatic birds at the surface of the water. It consists of a square PVC frame with a series of parallel flourocarbon stringers and a mesh basket to restrain the lure species. Nooses are attached to the stringers and used to ensnare the toes of a predatory bird. The trap is held afloat by the PVC frame, with the mesh basket, stringers, and nooses positioned just beneath the surface of the water. After determining effective trap placement in relation to perched birds, we captured 11 kites in 13 days with native pomacea paludosa (Florida Apple Snail) and exotic Pomacea insularum (Island Apple Snail) as lures. Our results indicated that the aquatic bal-chatri can be used to target specific Snail Kites and recapture previously trapped individuals. This trap design is a safe, efficient, and low-cost alternative to methods previously used for capturing Snail Kites. Additionally, the aquatic bal-chatri is relatively easy to use and appears to have minimal impact on foraging behavior and breeding performance of Snail Kites.