Off-nest behaviourof the Little Tern  Sterna albifrons during incubation

GOUTNER V. and CHARALAMBIDOU I.



Abstract:

The off-nest behaviour of the Little Tem Sterna albifrons was studied in the Axios Delta, a Macedonian wetland. The time taken up by the following components of this behaviour was measured during incubation in four nests and during different parts of the day: Away from nest, Shift during incubation, Chase of intruders, Throwing Sideways, Around nest, Wake Up and fly, Courtship Feeding and Human Disturbance. Data were analysed by Repeated-Measures ANOV A. There were significant effects of nest, day and part ofthe day on a number ofthese components of off-nest behaviour. The birds from one of the nests spent very different proportions of time on the various activities than those at the other nests. The effects ofthe part ofthe day were clear and some activities exhibited trends: time spent on Away and Shift typically decreased from the beginning to the end ofthe day, Human Disturbance was diminished in the third part ofthe day and Wake Up and Throwing Sideways were greater in the middle ofthe day. Despite clear day effects on many variables there was no regular pattem to these. There was also an interaction of day and part of the day on Away, Throwing Sideways, Human Disturbance and Wake Up denoting that these activities were affected by unpredictable events.