Cormorant capture methods for scientific research: field experience and review

Capturing cormorants is challenging due to their behavioural patterns, diverse colonial nesting habits and avoidance of humans. In this study, at first nine techniques were tested to capture Great Cormorant (Phalacrocorax carbo) at tree-breeding colonies and ground roosting sites across the Lithuanian coastal area in the south-eastern Baltic Sea. The use of mist nets, cannon nets and noose traps were found successful and are recommended, while other tested methods were shown as unsuccessful under the described conditions. As the second part, a review of published capture methods for all Phalacrocoracidae species presents varying methods at different locations, largely due to differences in landscape characteristics, vegetation cover and species-specific behaviour. We suggest that careful evaluation of site-specific conditions and bird behaviour is essential when selecting the most appropriate capture techniques and study colonies. Prioritising methods shown to be successful in comparable settings can reduce trial-and-error and save valuable time within limited capture windows to capture cormorants within the breeding season. We describe the capture methods applied to cormorants, adding practical insights and suggestions for successful, ethical and safe capture and handling of cormorants.