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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10277/144

Autori: Spada, Martina
Titolo: Environment, biodiversity and rare species: analysis of factors affecting bat conservation.
Abstract: To assess the conservation status of rare and threatened species it is necessary to have background information about their distribution, and population size and trends. While all these information are available for well-studied taxa, there is a lack of knowledge for other poorly studied species. Among Mammals, bats and rodents represent the orders with the larger than average percentage of Data Deficient species and information scarcity is one of the greatest threats to bats. The understanding and identification of key resources for bats is of vital importance for their conservation. In the present study we analysed the main ecological requirements of some rare bat species during breeding, mating and hibernation in Varese province (Lombardy, N Italy). The analyis of space use, activity pattern and resource selection during the breeding period was focused on a small colony of females Geoffroy’s bat (Myotis emarginatus), roosting in the town hall of a small city, through monitoring and radiotracking. The timing of birth was in the first days of July and lactation lasted for less than a month. After weaning animals abandoned the roost and in september they reached swarming/wintering sites. Geoffroy’s bat females exploited a restricted area, covering short distances during dispersion and between summer and wintering sites. Animals showed large home ranges without a centre of activity (core area), concentrating their foraging behaviour on mountain foothills on the interface between meadows and woodlands. The favourite preys were spiders, which formed three-quarters of arthropod fragments in bat droppings, followed by beetles, planthoppers, moths and mosquitoes. Lactating females appeared to use foraging areas located closer to the breeding site, although they didn’t nurse often the youngsters during the night: this may be better explained as a energy-saving behaviour during a period of high energetic constraint. Nightly activity pattern was the same for lactating and non reproductive females; they both showed an unimodal pattern, spending most of the time on the wing foraging, with a mean of 7 hours per night. The analysis of swarming and roosting behaviour during hibernation was centered on the analysis of bat activity and the characterisation of roosts in twelve underground sites of Campo dei Fiori Regional Park through monitoring. These caves were swarming and hibernating sites for six species, one of which was the Geoffroy’s bat, a species not known to swarm. Swarming activity started at the end of August, after a rapid decrease in mean environment temperature, and peaked in September. For all species sex ratio during swarming was skewed toward males (1:3), and this bias was even stronger for Myotis emarginatus (7% females). Bat activity was highest in caves positioned at high elevation, showing large entrances, low hydrological activity and exposition toward south-sothwest. The undergroud sites most used by animals were long and deep caves or short and shallow hollows: the former show a structure and hence microclimate suited for both swarming and hibernation, while the latter should be less fit for hibernation due to poor conditions of isolation from the athmosferic agents. Underground sites are key resources for bats, in relation to breeding, mating and hibernation, and their uneven distribution on the territory makes them used by a large number of bats that gather from a vaste area. In addition, bats show a high fidelity to single roosting sites, therefore the loss or deterioration of underground sites can result in a complete loss of suitable roosting place at a large scale, thus affecting different bat populations that could be subject to a decrease and a genetic deterioration. The two most abundant species in the caves of Campo dei Fiori Regional Park (Myotis emarginatus and M. nattereri) showed a positive trend during the last 11 years. This increase may be due to the protection efforts that has been put in bat conservation, but a longer data set is required to discern natural population fluctuations from real trends. The understanding of ecological requirements of rare and threatened species is imperative for the enhancement of effective conservation programs and the identification of features that affect bat choice of roosts is important to make predictions about the areas suitable for bat presence in order to concentrate our efforts in identifying new important roosting areas.
Data: 2009
Lingua: en
Corso di dottorato: Analisi, Protezione e Gestione delle Biodiversità
Ciclo di dottorato: 21
Università di conseguimento titolo: Università degli Studi dell'Insubria
Citazione: Spada, M.Environment, biodiversity and rare species: analysis of factors affecting bat conservation. (Doctoral Thesis, Università degli Studi dell'Insubria, 2009).

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