Efectes de la maduresa del bosc sobre les poblacions del nòctul petit (Nyctalus leisleri) a partir de l’ocupació de caixes refugi en fagedes del nord est de Catalunya

Abstract

The density and the distribution of lesser noctule (Nyctalus leisleri) can be conditioned by the structural heterogeneity and the availability of cavities in the wooden habitat. On the other hand, ecological factors as the trophic availability or the protection from predators probably are also conditioned by the forest structure. At the same time, wood structures depend on the management made on the forests. In order to answer these questions, the structure of beeches forests has been specialized in relation to relevant parameters for the use of nest boxes and noctule population has been sampled in different structures of beech forests in North–East of Catalonia. Therefore, it has determined the activity by means of inspection of nest boxes. They have been reviewed periodically in summer, winter and autumn during 2006 and 2014 a total of 382 nest boxes localized in different kind of beech forests. The results we got in the characterization of the different beech forests show a big contrast between them depending on the management to what they are being subjected : It is evident a decrease in structural heterogeneity and availability of cavities in immature beech woods and defectives. Whereas the results obtained for the taxes of occupation show an increase of the activity of the nest boxes in diminishing the maturity of the forests masses. It has been observed how the mature beech forests and the mature under silvicultural management, registered some taxes of low activity, whereas beech clarified woods and coppice woods registered a much higher occupancy rates. It has been observed also as a good forest specialist, the small noctule tends to occupy much more boxes located inside the forest, probably in search of greater thermal comfort and protection from predation. The maturity of the forests and, consequently, the management done on them, can influence in the distribution of lesser noctule on a wider geographic scale as it could be in a massif or in a country. It is recommended to focus the forest management of the beech woods of Catalonia on a way to promote the density of big trees with cavities in the trunk, as well as the interspecific heterogeneity and vegetative layers. It also presents as a valid alternative to try to stabilize the populations of small noctules, the location of nest boxes in beech forests where the natural shelter are scarce