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Title: Effects of seed availability on eurasian red squirrel (Sciurus vulgaris):life-history and demographic parameters in two pine forests in the italian Alps
Authors: Rodrigues, Diana Clamote
Orientador: Wauters, Lucas A.
Mathias, Maria da Luz, 1952-
Keywords: Mamíferos
Teses de mestrado
Issue Date: 2008
Abstract: Resumo alargado em português disponível no documento
In North Italy, the Eurasian red squirrel (Sciurus vulgaris) is threatened by the expansion of the introduced, invasive North-American grey squirrel (Sciurus carolinensis). Alpine conifer forests might constitute a stronghold for the long-term persistence of red squirrel populations in North Italy and adjacent countries. In resource limited systems, with a high degree of temporal variation in habitat quality, as Alpine conifer forests, the distribution and defensibility of critical resources are the main factors affecting life-history and demographic parameters of squirrels, which are still poorly understood in these more or less isolated and extreme habitats. In the present study, variation in tree-seed availability, red squirrels population densities, body size and mass and spacing patterns were monitored over different seasons in 2006 and 2007, to explore how differences in food availability between two alpine pine forests, Bormio (BOR) and Cancano (CAN), affected the behaviour and body condition of individual squirrels and the population densities, assuming that CAN was a marginal habitat contrary to BOR which was not one. Only in 2007, food availability was significantly different in the study sites, with seed-crop size being three times bigger at BOR than CAN. Red squirrels used larger home ranges and core areas and had a higher core area overlap at CAN than BOR, as predicted due to the need to meet daily energy-requirements. However, the expected increase in female-female core area overlap in CAN was not significant. Annual squirrel densities (BOR, 0.13 and 0.20 squirrels ha-1; CAN, 0.10 and 0.18 squirrels ha-1) and proportion of reproducing females were similar in both study sites and so was body mass, in contradiction with predictions that assumed lower density and body mass values for Cancano. These results suggest that there is no marked difference in habitat-quality between CAN and BOR and that the latter 'behaves' as a marginal habitat in years with poor pine-crops but as a medium-quality habitat in years of good pine-crops. Despite the logistic difficulties, future research should comprise long-term monitoring in both study sites and the comparison of lifehistory and demographic parameters from these populations with populations in other types of alpine forests, characterised by different temporal patterns in tree-seed availability and abundance.
Description: Tese de mestrado em Ecologia e Gestão Ambiental, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2008
Appears in Collections:FC - Dissertações de Mestrado

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