A general approach of using hair-tubes to monitor the European red squirrel: A method applicable at regional and national scales (original) (raw)
Related papers
During the nineties of the last Century, under the inspiration of Luigi Cagnolaro, it had been founded a " Sciurus group " , within the Research Centres of the Società Italiana di Scienze Naturali. Aim of the group was to start a campaign of researches on red squirrel populations in Lombardy, Italy promoting field master thesis on various topics: colour phases and indirect estimations of population densities. The researches were carried out during 10 years in 5 study areas. An investigation and census with questionnaires were started in parallel, with the collaboration of Forest Guards (CFS), Ecological Guards (GEV) and students of biological and natural sciences. The results were published in Italian or exposed in national and international congresses. This review has the purpose to show and critically discuss the overall results, and make them available to a broader audience. The dark colour phase, in the red squirrel, resulted associated to elevation and conifer woodlands, according to the thermoregulation theory, which consider the dark fur thicker and more suitable in cold environments. Squirrel population densities are subject to periodical fluctuations, in conifer woodlands, due to cones availability. Cone crops are subject to cycle with years of great production followed by years of lean. The recorded squirrel densities are middle-lows, but in line with data from similar environments.
A grey future for Europe: Sciurus carolinensis is replacing native red squirrels in Italy
Biological Invasions, 2014
Introduced mammals can cause extinction of native species due to replacement competition, disease, predation or hybridization. We studied the colonization of Piedmont (NW-Italy) by American grey squirrel (Sciurus carolinensis) and its effect on the native red squirrel (Sciurus vulgaris). Presence/ absence data (2 9 2 km 2 ), of both species were (re)constructed using questionnaires, literature, existing databases, unpublished information, and direct monitoring with hair-tubes. In 1970 red squirrels were still widespread and greys were restricted to forests near the introduction site. By 1990, grey squirrels had increased their range to 220 km 2 , which coincided with the disappearance of native squirrels from 33 squares inside this range. The invasive species continued its spread occupying an area of 2,016 km 2 in 2010; within this area red squirrels went extinct in 88 squares. Overall, from 1970 to 2010 red squirrel went extinct in 62 % of 2 9 2 km 2 (ca. 1,689 km 2 ), and were replaced by grey squirrels. The spread of the alien species was slow in the first 20 years, but doubled in the successive two decades. Nevertheless spread was slower than in Ireland and England. Grey squirrel adapt to climate and habitats in both North and South Europe, causing extinction of the native red squirrel. A EU LIFE co-funded project with the aim to control the grey squirrel in North Italy and recent trade-restrictions and trade-ban are a first step in reducing the risk of grey squirrels invading other countries, but their effectiveness will have to be evaluated.
Occupancy of isolated woodlots by the red squirrel Sciurus vulgaris L. in Italy
Biological Conservation, 1994
Effects of habitat fragmentation on the pattern of occupancy by the red squirrel Sciurus vulgaris were investigated in 46 isolated oakwoods in the Po Plain and 34 in the Apennines, where habitat structure variables were also measured Presence of the red squirrel was detected by the presence of dreys. Logistic regression analysis showed that only woodlot size in the Apennines and distance from the nearest 'source-area' in the Po Plain influenced the presence of the species. No habitat structure variable improved the models in the Apennines. Interdependent dynamics of patches and a 'source-sink' structure are suggested for the Apennine and the Po Plain study areas, respectively. In more isolated woodlots in the Po Plain short-term extinctions are likely to occur.
Biological Conservation, 2003
In 1997, the National Wildlife Institute, in co-operation with the University of Turin, produced an action plan to eradicate the American grey squirrel from Italy, as this introduced species replaces the native red squirrel through competitive exclusion and damages trees through de-barking. The first step, a trial eradication of a small population of grey squirrels at Racconigi (Turin) to evaluate the efficiency of the removal techniques, started in May 1997. Preliminary results showed that eradication was feasible, but the project was opposed by radical animal rights groups which took the National Wildlife Institute to court in June 1997. This legal action caused a suspension of the project and led to a lengthy judicial enquiry that ended in July 2000 with the acquittal of the Institute. Nevertheless, the 3-year suspension of all actions led to a significant expansion of the grey squirrel's range and thus eradication is no longer considered practical. Therefore, in the medium to long term, grey squirrels are likely to expand through continental Eurasia. This constitutes a major threat to the survival of the red squirrel over a large portion of its distribution range and will have a significant impact on forests, with economic damage to timber crops. #
Wildlife Biology, 1997
American grey squirrels Sciurus carolinensis introduced to northern Italy in 1948 have caused damage to commercial poplar plantations and have replaced the native red squirrel Sciurus vulgaris from most of the 350 km2 of the Piedmont Po‐plain they currently occupy. In order to plan a control programme aiming to stop grey squirrels from further spreading and to decrease their numbers, the current distribution and population size in the highly fragmented landscape of the Po‐plain were studied. The probability of finding grey squirrels in woodland fragments increased with habitat quality (diversity of trees producing large, consumable seeds), woodlot size and the proportion of poplar. Adding isolation variables did not improve the fit of the logistic regression model that predicted squirrel presence. The density of squirrel dreys, an index of population density, in the large Stupinigi forest also increased with tree species diversity. An estimate of the minimum population size for all ...
Headcount 2010: The Multiplication of the Grey Squirrel Introduced in Italy
2010
The introduction of non-native animal species is an important cause of loss of biodiversity. Tree squirrels as a taxon and grey squirrels (Sciurus carolinensis) in particular are among the most successful invasive alien species. Here we present the current situation (October 2010) of the grey squirrel in Italy. The grey squirrel was first reported in Piedmont in 1948. Subsequent major introductions were reported in Genova-Nervi (1966) and the Ticino Valley Regional Park in Lombardy (1999). In 2010, there were 24 areas with a (meta) population or nucleus of grey squirrels: 23 of these were in the three regions most affected by the invasive species Piedmont, Lombardy and Liguria. The number of known areas with grey squirrel presence has strongly increased in the last years. With the exception of the Genova-Nervi population, there is a lack of detailed knowledge on grey squirrel distribution and population size in areas where animals are now known or believed to be present. We underlin...