Consultez les articles du Bulletin Aves !
Aves, 12/3 | 1975 | 130-159
Having localized and described the biotpoe used each winter as roosting place by a small population of Hen harriers (Circus cyaneus), the author synthesizes numerical and ethological data gathered by a group of local ornithologists during 150 observation trips spread over 7 years. Observations were led in order to be able to describe the Hen Harriers' behaviour and to note their time of arrival and of resting according to sunset. Winter is arbitrarily divided into four periods which all but the second show a peak in the number of exemplars present, and the causes of these fluctuations are studied. Inter- and intrapspecific relations are tackled. Some vocal manifestations are described and theories are formed as for their motivation. Finally, the Hen Harriers' diet during winter stays in Belgian Lorraine has been established by pellet analysis and a map showing the distribution of the hunting territories has been completed. The Hen Harrier can be regarded as a regular winter visitor in Belgian Lorraine but this region is only a small part of the whole wintering area. Similar studies should lead to a better knowledge of the winter ecology and ethology of this bird of prey in continental Europe and synchronous numberings should permit to follow the fluctuations of population.