|
Résumé :
|
Despite the widespread distribution of the Lesser Spotted Woodpecker. many aspects of the species' biology are poorly known, particularly regarding its habitat requirements in central European forests. Recent studies suggest population declines in many areas of its range, making the need for appropriate management guidelines urgent. In 1997, we examined which habitat factors affect the presence of the Lesser Spotted Woodpecker in deciduous lowland, non-riverine forests of northeastern Switzerland and evaluated the usefulness of playback tapes for censusing the species. Selected on the basis of prior knowledge of the species' distribution, 27 forests were searched for Lesser Spotted Woodpeckers using playbacks from March to early May. The species was still present in 17 of these formerly occupied forests, while 5 new registrations were made in previously unoccupied forests. Ninety percent of the registrations occurred between 16 March and 24 April, and the woodpeckers responded to the playbacks most often with call series. The habitat structure of forests with Lesser Spotted Woodpeckers was compared with that of forests where the species had been absent both during previous censuses and in 1997, and which had a similar tree species composition, forest structure and elevation to the occupied forests. Logistic regression analysis identified four habitat variables as significant predictors of the species' presence/absence. Accordingly, forests were most likely occupied by the Lesser Spotted Woodpecker if more softwoods, but fewer snags (with a DBH greater than or equal to 15 cm) per area were available, if the distance to lakes and rivers was small, and the elevation was low. Therefore, the distribution of the Lesser Spotted Woodpecker seems to be affected by variables reflecting both forest structure and relative position of the forests within the landscape. We conclude that the Lesser Spotted Woodpecker will benefit from protection and promotion of softwood in all forest types, resulting in increased habitat connectivity. Moreover, censuses using playbacks can be efficiently conducted during a short period in March/April.
|