Responses to human disturbance from nesting Gull-billed Terns. - E.V. Barbazyuk. - Berkut. 14 (2). 2005. - P. 221-230.
The phenomenon of nest relocation was found in colonies of Gull-billed Terns on Lakes Shalkar and Ayke, southern Russia, in 2000 and 2001. The phenomenon manifested itself largely on Lake Shalkar in 2001, while research work was conducted in a Gull-billed Tern colony. After visiting the island that colony occupied, during 14 days it was observed that some birds had abandoned their nests mainly in the densest plots of the colony, and at the same time new nests had appeared on the colony periphery. A typical detached nesting site of the colony (the sample plot) was charted on the map. In the sample plot, the number of nests decreased 1.7 times – from 113, before research work, to 68, after work in the colony. The sample plot area increased from 130.8 m2 to 161.3 m2, the length increased from 19.0 m to 21.1 m. Mean nearest-neighbor distance increased from 70.6 ± 2.2 cm (n = 113) to 96.4 ± 4.9 cm (n = 68; t180 = 5.5; p < 0.0001), density reduced 2.1 times – from 0.9 to 0.4 nests per m2. It is supposed that such changes in the colony territorial structure resulted from repeated human disturbance caused by the long-term research activity in this colony of Gull-billed Terns. [English].
Key words: Gull-billed Tern, Gelochelidon nilotica, human disturbance, density, colony, nest relocation.
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.