Experimental study of territorial structure in the Gull-billed Tern. - E.V. Barbazyuk. - Berkut. 14 (1). 2005. - P. 111-123.
The nest territory structure and territorial behavior of the Gull-billed Tern was studied at Lakes Shalkar and Ayke (southern Russia) in 2000, 2001 and 2003. To examine the defended area around nests, field experiments were conducted during which one nest was moved gradually toward the nearest neighboring nest. The area surrounding a Gull-billed Tern nest was shown to consist of at least three territorial units, not visible by direct observation: immediately surrounding the nest is a small area designated as the Core Area; the Core Area is surrounded by a larger area called the Conflict Zone, consisting of a more aggressive Inner Layer directly bor-dering the Core Zone, and a less aggressive Outer Layer. The hostility of the both birds increased as the distance between the nests lessened. In the Core Area tern aggression was maximal, and was expressed by absolute in-tolerance of other individuals. [English].
Key words: Gull-billed Tern, Gelochelidon nilotica, territorial behaviour, colony, nest territory structure.
Address: E.V. Barbazyuk, Laboratory of Biocenological Processes, Institute of Plant and Animal Ecology, 8-Marta St., 202, Ekaterinburg, 620144, Russia; e-mail: bev@mail.esoo.ru.