THE BATS OF GRAN PARADISO NATIONAL PARK: A PRELIMINARY CHARACTERIZATION BASED ON SUMMER SURVEYS

Abstract

ABSTRACT

From 2011 to 2015, we carried out summer surveys aimed at inventorying bat species and furnishing a preliminary characterization of their distribution in Gran Paradiso National Park, the largest protected area in the Western Italian Alps. Data were collected through mist-netting, acoustic recording and inspection of potential roost sites.

A total of 187 individuals were mist-netted, belonging to 10 different species. Among them, P. pipistrellus and P. macrobullaris were the most abundant and frequently caught, respectively on water bodies and on alpine pastures and prairies.

At least 14 species were detected through acoustic surveys.

Most of the acoustic data resulted from operating according to standardized protocols involving early and late summer samplings at fixed points located far from artificial light sources. P. pipistrellus, genus Myotis and H. savii, in this order, were the most recorded taxa in ecotones (wood edges, clearings, forest trails) and open habitat types (pastures above current forest limits) between 800 and 2200 m a.s.l. No clear dominance of any species or acoustic group could be recognized in the recordings collected between 2200 and 2600 m, although at a site where a greater sampling effort was performed genus Plecotus turned out to be the most record taxon. Acoustic and mist-netting data revealed the presence at high elevations of species such as P. macrobullaris and T. teniotis – which certainly find there both foraging and roosting opportunities – together with bats usually associated with lower elevations, like M. myotis vel blythii and N. leisleri, possibly attracted to pastures and prairies by the availability of some prey.

As a general trend, mean bat activity decreased with elevation and when moving to zones with a simpler vegetation structure, but profound differences, both in terms of activity and species occurrence, were observed on a local basis.

Two open areas of a same valley, both characterized by pastures, absence of artificial lighting and similar elevation (about 2000-2100 m), but differing in other ecological conditions (presence/absence of lentic water bodies, distance from woods, exposition, zootechnical use) were surveyed more in depths. In one area bat activity resulted by far dominated by P. pipistrellus, with genus Myotis and E. nilssonii following far behind; in the other area co-dominance of H. savii and P. pipistrellus was observed, while the next most recorded acoustic category was the group of species Eptesicus serotinus/ Vespertilio murinus/ Nyctalus leisleri/ Nyctalus noctula.

Part of the acoustic surveys were carried out in presence of insect-attractive artificial light sources. Results suggest that artificial lighting plays an important role in conditioning the presence and the activity of bats in the Park. According to the preliminary data collected along valley bottoms, genera Myotis and Plecotus and B. barbastellus seem to occur more frequently at unlighted than at lighted sites. At high elevation profound differences were observed between a strongly lighted and some unlighted sites: total bat activity was exceptionally higher at the former; moreover, data suggested different levels of attraction to forage at lamps among bat species and  no attraction at all for genus Myotis.

Because of the scarcity of underground sites in the Park, only few results were obtained by inspecting potential roost sites. Sixteen roost (mainly in buildings) were identified; they were used by at least 5 species, among which P. macrobullaris prevailed.

As a whole, the presence of at least 16 bat species was ascertained in the Park: M. daubentonii, M. mystacinus, Myotis myotis vel blythii, Myotis nattereri complex, P. kuhlii, P. pipistrellus, P. pygmaeus, H. savii, E. nilssonii, E. serotinus, V. murinus,  N. leisleri, P. auritus, P. macrobullaris, B. barbastellus and T. teniotis. For most of the species national altitudinal records were recorded.

Keywords: Bats, Chiroptera, Parco Nazionale Gran Paradiso, Alps, distribution, elevation, artificial lighting.

* Corresponding Author: Elena Patriarca, S.Te.P.  c/o Museo Civ. St. Nat., via S. Francesco di Sales, 188; 10022 Carmagnola (TO) Email: teriologi@gmail.com