Simulation of the spread of grey squirrels. Different colours represent the predicted densities (no/ha) at 10 year intervals. a) year 2011; b) year 2021; c) year 2031; d) year 2041.

Istituto Oikos, ONG Vareses, Italy carried out the research for Parco Regionale della Valle del Ticino Lombardo. Guido Tosi was the Prof. in charge.

Investigation of the Asian chipmunk(Eutamias sibiricus Laxmann 1769) in De Panne (Belgium)

by Goedele Verbeyen - 17th January 2001

The Asian chipmunk is being imported in Belgium as a pet since the beginning of the sixties. Now there are four free-living populations in Belgium, one in the Zoniënwoud (Brussels, estimated at 18.000 individuals in 2000!), one in Westerlo, one in a Castle park in Zwijnaarde and the one from this study in the Calmeynbos in De Panne. About 20 years ago, 17 animals were released in the Calmeynbos by the amusement park Meli. In their original distribution area these animals can, at high densities, cause a lot of damage to agricultural fields. In the Zoniënwoud a negative influence on some ground breeding birds is indicated. Because of the danger of negative consequences on the ecological system due to increasing population pressure, preventive measures have been suggested. There is the need of a more specific study of the interaction of the chipmunks with the forestal ecological system. At first step taken in this direction is this study, conducted in fall 1998, 1999 and 2000 in De Panne.

The aim of this project is to estimate chipmunk numbers and distribution and to look at their behaviour (especially feeding habits). The study includes two parts : (1) an estimation of the population density based on the transect method in the whole study area and (2) a more accurate estimation of the population density based on capture-mark-recapture data in part of the study area.

The chipmunks preferred the forested area but in years with high densities they spread out in the surrounding gardens and dunes. Estimates were about 350 chipmunks in 1998, 160 in 1999 and 70 in 2000, so there seems to be a decrease in population size. The low number of chipmunks left in 2000 were concentrated in the part of the forest with the most food. The forest is divided by a road, with remarkable differences in sex ratio between both sides: at one side, with a low chipmunk density, sex ratio was about 1:1, while at the other side, with much higher densities, there were about 4 females for 1 male.

Pallas's squirrel (Callosciurus erythraeus erythrogaster) in France

by Peter Lurz - 8th September 2003

Pallas’s Squirrel was introduced to Cap d’Antibes in the 1970s. The species is thought to occur at higher densities than the native red squirrel and causes damage to trees and crops in the area (Jouanin 1990, 1992). Measurements of specimens are reported as: tail: 163-193 mm, head and body length: 204-225 mm and weight: 340-360 g.

Literature

• Jouanin, C. 1990. L’ecureuil a ventre rouge d’Antibes. In: Introductions et reintroductions de mammiferes sauvages. (ed. M. Guernieau). Actes du XIV Colloque Francophone de Mammalogie de la Societe Francaise pour L’Etude et la Protection des Mammiferes, Orleans 1990.
• Jouanin, C. (1992) L'écureuil à ventre rouge d'Antibes. In: Introductions and réintroductions des Mammiferes sauvages. Actes du XIVème colloque francophone de Mammalogie de la Société française pour l'étude et la protection des Mammifères. Orlèans/Saint Jean de Braye: 277-284.
• Mitchel-Jones et al. (1999). The Atlas of European Mammals. Poyser Natural History, Academic Press, London.

The Finlayson's squirrel Callosciurus finlaysoni : a new alien squirrel in Italy

by Sandro Bertolino - 1st January 2001

The Finlayson's squirrel Callosciurus finlaysoni is a species naturally present in Burma, Thailand, Laos, Cambodia and South Vietnam. In 1998 a population of this species was found in a 2 ha park at Acqui Terme (44°40'N - 8°28'E, province of Alessandria, northwestern Italy). It took origin from two couples released 18 years ago; about 40-50 animals were estimated to be present in 1999.

At Acqui Terme squirrels built their dreys both in broadleaf and conifer trees, and use tree holes as well. Reproductive activity was observed in April, July and November/December, while juveniles were seen outside the dreys in June, September, and February.Squirrels consume fruits, flowers, buds, and sap; frequently they were observed eating insects and honeydew on trees. Several old broadleaf and conifer trees present in the park show evident bark-stripping wounds, sometimes so wide to compromise the survival of the trees.

A risk assessment for the Finlayson's squirrel in Italy was performed and showed that the species seems to be able to adapt to Italian habitats. The potential high reproductive ratio will probably lead to the colonisation of woodlands in the hills around the city. In such a case, a medium to high degree of damage can be expected through bark-stripping and fruit consumption (e.g. in orchards, vineyards, hazelnut plantations). For this reason, and considering the experience developed in Italy and UK on the grey squirrel, the removal of the species was strongly recommended. Anyway, operating in a town park puts several problems on the choice of the most efficient and acceptable method to be used.

Literature

• Bertolino S. (in press) Reducing the risks of non-indigenous species introduction: rodents and lagomorphs. Biol. Cons. Fauna.
• Bertolino S., Currado I., Mazzoglio P.J. & Amori G. (in press) Native and alien squirrels in Italy. Hystris Italian Journal of Mammalogy.
• Bertolino S., Currado I. & Mazzoglio P.J. (1999a) Finlayson's (Variable) Squirrel Callosciurus finlaysoni in Italy. Mammalia, 63 (4): 522-525.
• Bertolino S., Mazzoglio P.J., Vaiana M. & Currado I. (in press) Reproductive biology and bark-stripping behaviour of Callosciurus finlaysoni (Rodentia, Sciuridae) in Italy. Biol. Cons. Fauna.

The grey squirrel in Italy: species expansion and threats for neighbouring countries

by Sandro Bertolino - 1st January 2001

Origin and spread of the grey squirrel in Italy

The grey squirrel was introduced into Piedmont (north-western Italy) in 1948, when two pairs were released at Stupinigi (province of Turin) (Bertolino et al., 2000). In 1966, 5 animals imported from Norfolk (Virginia, USA) were released into the park of Villa Groppallo at Genoa Nervi. The Piedmont population has shown a rapid increase of its range in the last decades. From their introduction until 1970 the grey squirrel was recorded only close to the release site, occupying an area of about 25 Km2 (Wauters et al., 1997). Subsequently, the species started to spread into the surrounding area: in 1990 the species' range arrived to 243 Km2, in 1997 to 380 Km2. After 1997 the range showed a dramatic increase, and in 1999 the grey squirrel was present in an area of 880 Km2 (Wauters et al., 1997; Bertolino and Genovesi, submitted).

Competition with red squirrel and damage

The grey squirrel was introduced into Great Britain and Ireland several times from the end of the last century, causing the progressive disappearance of the native red squirrel from a wide portion of the two islands (Reynolds 1985, Gurnell and Pepper 1993), and severe damage to forests and commercial tree plantations (Rowe and Gill 1985, Dagnall et al. 1998). Bark-stripping activity inflicts wounds that severely degrade timber quality and can facilitate the penetration of insects and fungi (Kenward 1989). It is remarkable that gray squirrel produces little damage to tree in its native area in north America (Kenward 1989). Italian data confirm the competitive exclusion of the red squirrel from the grey squirrel range. A distribution survey in the area where grey squirrels are present, showed a reduction of 46% in the range of the red squirrel from 1970 to 1990, and a further decrease of 55% from 1990 to 1996 (Wauters et al. 1997a).

Eradication proposal and failure of the project

In respect to the urgency of remove the grey squirrel from Italy, in 1997 the NWI (National Wildlife Institute), in co-operation with the University of Turin, produced an action plan finalised to the eradication of the alien species. One of the first steps of the plan was the experimental removal of the small population present in the Racconigi park, in order to produce a pilot eradication scheme. The trial eradication started in May 1997, and the preliminary results were very encouraging, but some animal right groups took the NWI to court, managing to halt the project. In July 2000 the Appeal Court of Turin discharged the two officers.

Outcomes

The three years legal struggle determined the failure of the campaign. Since then, as a consequence of the suspension of the eradication campaign, the species has significantly expanded its range and nowadays the complete eradication is considered not feasible anymore (Genovesi and Bertolino 2000). In fact, the range of the grey squirrel has reached the continous wood belt of the Alps, and of the hilly system of the eastern Piedmont. The dramatic expansion of the species' range in the last two years, and the homogeneous and continuous broadleaf woodlands characterising the Alpine region, make a colonisation of the entire alpine arch in a few years very probable. Such pessimistic prediction is also supported by the results of a model developed by Lurz et al. (submitted), that predicts that grey squirrel spread is likely to speed up once they are in the pre-alpine forest due to reduced fragmentation, and indicate two possible scenarios, with the greys across Alps and in France in 30-50 years. The NWI to produce a strategy for the control of the Grey squirrel, and after an assessment of the range expansion, the NWI proposed a strategy aimed to: 1) identify and protect key areas for the conservation of viable populations of red squirrels, 2) contain the grey squirrel in order to delay its expansion to neighbouring countries and to the mountain system of Italy (Genovesi and Bertolino 2000).

Threats to other countries

The grey squirrel has colonised in Italy a mean of 17.2 Km2 per year, similarly to the values reported for Great Britain (18 Km2/year, Okubo et al., 1989). The colonisation of new areas has not been constant since 1970, ranging from 1.1 Km2/year in the first phase, when the spread outside the wooded area of Stupinigi was hindered by the presence of extended cultivated fields with a very reduced and fragmented woods, to 10-20 Km2/year, once the species started spreading along the rivers, and recently increased to 250 Km2/year, when the grey squirrel reached the hilly areas of eastern Piedmont and the Po river (Bertolino & Genovesi, submitted). Considering these data and the model developed by Lurz et al. (submitted), a scenario with the grey squirrel through the Alps and in France in the next decades is likely.

References

• Bertolino, S., Currado, I., Mazzoglio, P.J., Amori, G., 2000. Native and alien squirrels in Italy. Hystrix Italian Journal of Mammalogy (n.s.) 11 (2), 49-58 .
• Bertolino, S. and P. Genovesi (submitted). Eradication of the grey squirrel (Sciurus carolinensis) from Italy: failure of the project and consequences for red squirrel (Sciurus vulgaris) conservation in Eurasia
• Dagnall, J., Gurnell, J., Pepper, H., 1998. Bark-stripping by gray squirrels in state forests of the United Kingdom: a review.
  In: Steele, M.A., Merritt, J.F., Zegers, D.A., (Ed). Ecology and Evolutionary Biology of Tree Squirrels. Virginia Museum of Natural History, Special Publication, n. 6, 249-261.
• Genovesi, P., Bertolino, S., 2000. Piano di Azione Nazionale per il controllo dello Scoiattolo grigio (Scirus carolinensis). Ministero dell'Ambiente, Servizio Conservazione della natura, pp. 31.
• Gurnell, J., Pepper, H., 1993. A critical look at conserving the British red squirrel Sciurus vulgaris. Mamm. Rev. 23, 125-136.
• Kenward, R. E., 1989. Bark-stripping by grey squirrels in Britain and North America: why does the damage differ? In: Putman, R.J., (Ed), Mammals as Pests. Chapman and Hall, pp. 144-154.
• Lurz P.W.W., Rushton S.P., Wauters L.A., Bertolino S., Currado I. , Mazzoglio P.J, (submitted). Predicting grey squirrel expansion in North Italy: a spatially explicit modelling approach.
• Okubo, A., Maini, P.K., Williamson, M.H., Murray, J.D., 1989. On the spatial spread of the grey squirrel in Britain. Proocedings of the Royal Society of London B 238, 113-125.
• Reynolds, J.C., 1985. Details of the geographic replacement of the red squirrel (Sciurus vulgaris) by the grey squirrel (Sciurus carolinensis) in eastern England. J. Anim. Ecology 54, 149-162.
• Rowe, J.J., Gill, M.A., 1985. The susceptibility of tree species to bark-stripping damage by grey squirrels (Sciurus carolinensis) in England and Wales. Quaterly Journal of Forestry 79, 183-190.
• Wauters, L.A., Currado, I., Mazzoglio, P.J., Gurnell, J., 1997. Replacement of red squirrels by introduced grey squirrels in Italy. In: Gurnell, J., Lurz, P., (Ed), The Conservation of Red Squirrels, Sciurus vulgaris L. People Trust for Endangered Species, pp. 79-88.

National Wildlife Institute condemned for illegal hunting and cruelty - November 26th 1999.

30th November 1999

On November 26th, I and the director of my institute were condemned for illegal hunting and cruelty towards animals, for the trial eradication of the grey squirrel that I coordinated in Piedmont (north-west Italy) in 1997.

This is the last step of a long story. The National Wildlife Institute, where I work as a researcher, is the Italian government agency for research and management of wildlife. In recent years, we received alarmed communications from several Italian and foreign organisations (including WWF and IUCN) underlying the need to eradicate the introduced grey squirrel (Sciurus carolinensis) from Italy.

UK data show that the grey squirrel causes the extinction of the autochtonous red squirrel (S. vulgaris), and the same is happening in Italy: the red squirrel has in fact disappeared from all of the range colonised by the alien species. There is a real possibility that the Italian population of the grey squirrel will spread to the Alps and to neighbouring countries, potentially causing an ecological catastrophe in all of continental Europe.

In this respect, in 1995 we made an official resolution asking the Ministry of Environment, the Ministry of Agriculture, and the provincial and regional administrations of Piedmont to eradicate the grey squirrel. Furthermore, in 1996 we asked the Health Ministry to stop the import of grey squirrels.

At the end of 1996 we programmed a trial eradication. For the Italian legislation, our Institute is competent for research and for giving advice on pest control methods, but pest control only can be directly done by regional and provincial wildlife services. The study was based on the experience of coypu in the UK, and was aimed:

• to test the efficency and reliability of an eradication campaign using live trapping
• to carry on sanitary researches to test for the presence of parapoxvirus, that was suspected to be present in the grey squirrel population

The plan was to provide the provincial wildlife services with guidelines for the eradication, based on rthe results from the trial eradication.

The trial eradication programme was sent to NGOs for comments, and opposition to the plans was raised by Animal Rights Groups. For this reason we met the Animal Rights Groups to explain the aims of the programme, and asking for suggestions on how to minimise animals stress. On the basis of the comments we received, we decided to use halothane (an anesthetic that causes little stress in rodents) to tranquillise and euthanise the squirrels. Other suggestions (e.g. taking back the grey squirrels to North America, taking all the animals to an island, neutering all the squirrels and releasing them in the wild) were discussed and rejected by our team.

The programme was officially presented to the regional authorities in April 1997. At a meeting involving NGOs: several NGOs (e.g. WWF, Bird protection organisations) approved the programme, while the League Against Hunting, the League Against Experiments on Animals, and Other Animals (a branch of Legambiente, the second largest environmental NGO in Italy), opposed the project.

We started the trial eradication in May 1997 in the Racconigi Park, and the results were very encouraging: half of the local population was removed within 2 weeks, and the use of halothane determined rapid unconsciusness of animals before euthanasia.

In June we were taken to court by the 3 Animal Rights Groups. The court trial started in 1997 (justice in Italy is very slow); we have been defended by the State lawyer service. An officer of the Ministry of Environment witnessed that we were acting to protect the Italian fauna, and recalled that Italy signed the Rio Convention and the Bern Convention imposing States to eradicate allochtonous species threatening biodiversity.

The Animal Rights Groups were supported by Giorgio Celli, an entomologist at the University of Bologna who is very famous in Italy for his television programme, and was recently elected by the Green Party to the European parliament (during the trial he was in the middle of his electoral campaign).

In the trial they affirmed that it is impossible to eradicate a species (they also affirm that the coypus has not been eradicated from UK); that it is not sure that the grey squirrel replaces the red squirrel; that we should have neuterised all the squirrels instead of "gasing" them.

Incredibly, the judge condemned us (cruelty toward animals for the Italian legislation means to determine sufferences without any purpose, other than the personal enjoyment....). It was very likley that the personal fame of Celli played a role in the decision.

Of course we will appeal, but it will take 2-3 years to arrive to a final judgement. The penalty is a fine of few thousand dollars (for a long time we have been asking for stiffer penalties for poachers; it is good that the parliament did not follow our advice....), but provincial administrators will be unlikely to decide to start the eradication before the legal case is closed.

In the mean while, the grey squirrel rapidly expanded its range, it has recently been recorded very close to the Alps (through hair trap monitoring), and I am quite pessimistic on the possibility to eradicate the species in the future.

The media reported the Animal Rights Groups declarations (including our condemnation as a stop to 'slaughter', and asking for a new Institute to protect of allochtonous species in Italy).NGOs (who firstly promoted and supported the eradication trial) adopted a low profile so as not to cause a split between their two internal wings: animal rights and conservation supporters.

All Italian conservationists supported our Institute, but at the moment we have not succeeded in making media report our position. I am trying to contact journalists, and many collegues are doing the same.

If the grey squirrel expands its range as we fear, I hope that this story will at least become an example to show people the threats caused by biological invasions, and to promote the acceptance of eradications as a means for conservation.