Proceedings of the Vertebrate Pest Conference

Double-crested Cormorants (Phalacrocorax auritus) often roost in cypress oxbows and nest on islands making their capture for research studies difficult. In the southeastern United States we used a capture technique involving a boat equipped with flood lights, flushing the birds out of their roost trees, and capturing them with a landing net. On the Great Lakes we devised a capture technique using modified padded leg-hold traps placed in nest trees or on the ground in the colony. We captured >250 cormorants using these two techniques with very few injuries to the birds. In a study with captive birds, we evaluated the short-term effects of backpack and patagial tag VHF transmitters and their attachment techniques for use on cormorants. We conclude that backpack VHF transmitters are applicable for use on double-crested cormorants and that patagial solar powered transmitters should be further tested. We also tested two methods for simultaneously attaching a VHF transmitter and a backpack satellite transmitter to cormorants. Birds with the VHF patagial tag attachment showed moderate to heavy feather wear and abrasions on the ventral surface of the patagium. We recommend gluing the VHF transmitter to the backpack satellite transmitter for attaching both VHF and satellite transmitters to double-crested cormorants. These adaptable cormorant capture and telemetry techniques should prove suitable for use in other habitats and situations.