Time filter

Source Type

Rulison E.L.,Hofstra University | Luiselli L.,Centro di Studi Ambientali Demetra Srl | Burke R.L.,Hofstra University
American Midland Naturalist | Year: 2012

We compared relative impacts of habitat type vs. location in the diet of a generalist omnivore, the raccoon (Procyon lotor). Raccoon diets were analyzed from 161 scat samples collected in a marine coastal habitat over 13 mo. We used a suite of statistical tools including univariate indices of diversity, descriptive statistics, niche similarity analyses, and two contrasted randomization algorithms with Monte Carlo to test whether raccoons maintained similar diets in different habitats. We compared these results to raccoon diet studies in geographically distant locations with similar habitats to relevant studies conducted geographically closer but with different habitats. Logistic regression analyses revealed that among habitat similarity, geographic closeness, and diet diversity (i.e., relative dietary specialization of each population), only habitat similarity significantly (and positively) influenced probability of observing a greater-than-expected diet similarity. This demonstrated that raccoons in similar habitats had similar diets, with substitution of ecologically equivalent prey species.

Battisti C.,Environmental Service Inc. | Luiselli L.,Centro di Studi Ambientali Demetra Srl
Journal for Nature Conservation | Year: 2011

In connectivity conservation and ecological network planning, the selection of focal fragmentation-sensitive species represents a priority step. Nevertheless, despite their strategic role, selection of focal species has traditionally been carried out using charismatic and/or non objective approaches. In this way, actions of planning and conservation could be ineffective. Using as a case study Italian reptiles, we apply an expert-based approach for the selection of focal species on the basis of sensitivity to components of habitat fragmentation (habitat area reduction, increase of habitat isolation, increase of edge effect and landscape matrix disturbance) and of intrinsic ecological traits of the species (trophic level, dispersal ability, body size, niche breadth, rarity). The threshold values for each component of fragmentation defined a set of 21 focal species that can be divided into the three macro-components of human-induced habitat fragmentation (HIHF) towards which they show a sensitivity, the suitable spatial scale of populations and relative suitable habitat categories. Among these species, seven can be sampled easily with standard, low-cost field protocols. The selected species largely coincide with the species known in literature as fragmentation-sensitive. © 2010 Elsevier GmbH.

Walker R.,Nautilus Ecology | Walker R.,Open University Milton Keynes | Luiselli L.,Centro di Studi Ambientali Demetra Srl | Rafeliarisoa T.,University of Antananarivo | Rafeliarisoa T.,Grewcocks Center for Conservation and Research
Amphibia Reptilia | Year: 2012

The spider tortoise (Pyxis arachnoides) is endemic to the coastal, dry forests of southwest Madagascar, one of the country's most threatened habitats. Very little is known of the biology of this Critically Endangered species. We devised a three year capture-mark-recapture study to assess mean annual survival for the following cohorts; juvenile, adult male, adult female and adult of both sexes, for a population of spider tortoises using a Cormack-Jolly-Seber model. Low recapture probabilities prevented the modelling of all but the adult of both sexes cohort. Mean annual survival was 0.823 (SE = 0.15; 95% CI = 0.565-1.0). We hypothesise that habitat loss could be impacting the survival of this cohort; however establishing control data to test for this is difficult because of the widespread habitat loss, even within protected areas. Therefore we suggest extending the study across a number of gradients of impacted habitat and increase the duration of the study to assess this risk to the population and improve model robustness. © 2012 Koninklijke Brill NV, Leiden.

Mebert K.,University of Basel | Jagar T.,Herpetolosko drustvo Societas herpetologica slovenica | Grzelj R.,Herpetolosko drustvo Societas herpetologica slovenica | Cafuta V.,Herpetolosko drustvo Societas herpetologica slovenica | And 7 more authors.
Biological Journal of the Linnean Society | Year: 2015

Contact zones of closely related and ecologically similar species constitute rare opportunities to study the evolutionary consequences of past speciation processes. They represent natural laboratories in which strong competition could lead to the exclusion of one species, or the various species may switch into distinct ecological niches. Alternatively, if reproductive isolation has not yet been achieved, they may hybridize. We elucidate the degree of taxon integrity by comparing genetics and habitat use of three similar-sized congeneric viper species, Vipera ammodytes, Vipera aspis, and Vipera berus, of Nadiza Valley in western Slovenia. No hybridization was detected for either mitochondrial or nuclear genomes. Similarly, external intermediacy by a single prestudy viper (probably V. ammodytes × V. aspis) indicates that hybridization occasionally occurs, but should be very rare. Populations of the three related viperids are partially allopatric in Nadiza Valley, but they also coexist in a narrow contact zone in the montane grassland along the south-exposed slope of Mount Stol (1673 m a.s.l.). Here, the three species that occupy areas in or near patches of rocky microhabitats (e.g. stone piles, slides, and walls) live in syntopy. However, fine-scale measurements of structural components show partial habitat segregation, in which V. berus becomes more dominant at elevations above 1400 m and occupies mostly the mountain ridge and north-exposed slopes of Mount Stol, V. aspis occurs below 1300 m and is the only species to inhabit stoneless patches of grass and bushes around 1000 m and lower, and V. ammodytes occurs at all elevations up to 1500 m, but is restricted to a rocky microhabitat. We suggest that a high degree of microstructure divergence, slightly different environmental niches, and a generally favourable habitat for all three viper species, keep the pressure for mis-mating and hybridization low, although mechanisms such as reduced hybrid inferiority and temporal mating segregation cannot yet be excluded. © 2015 The Linnean Society of London.

Filippi E.,Centro di Studi Ambientali Demetra Srl | Rugiero L.,Centro di Studi Ambientali Demetra Srl | Capula M.,Museo Civico di Zoologia | Burke R.L.,Hofstra University | Luiselli L.,Centro di Studi Ambientali Demetra Srl
Chelonian Conservation and Biology | Year: 2010

Herman's tortoise, Testudo h. hermanni, is an endangered subspecies in Italy, France, and Spain. We studied a Herman's tortoise population in the Riserva Naturale Regionale Monterano in the Tolfa Mountains of central Italy. We found that, unlike most other studies of this and related species, sex ratios were 11, and half the population was made up of juveniles. Sexual maturity was reached at 12 years in males and 1213 years in females, and females were significantly larger. Tortoises greatly preferred open maquis habitat over other habitat types and thermoregulated so that body temperatures stayed consistently above ambient temperatures, especially under low ambient temperature conditions. Presence of ticks was significantly associated with an index of thermoregulatory behavior. We suggest that maintenance of open maquis habitat in this reserve is essential to high hatchling production and effective thermoregulation. © 2010 Chelonian Research Foundation.

Discover hidden collaborations