sign in sign up
<<
Home , Province of Novara, Siberian chipmunk, Squirrel, Trecate

Hystrix, (n.s.) 11 (2) (2000): 65-74

NATIVE AND ALIEN IN

SANDRO BERTOLINO", ITALO CURRADO", PETER J. MAZZOGLIO" AND GIOVANNIAMORI"

* Di. Va2R.A. Entomologia e Zoologia, Universita di Torino, via L. da Vinci 44, 10095 Grugliasco (TO), Italy.

O CNR, Centro Genetica Evoluzionistica, via Lancisi 29, 00161 Roma, Italy.

ABSTRACT - In Italy there are four of squirrels: the native red and other three species recently introduced. The is present in the Italian peninsula with three subspecies, and is missing only in Salento, and Italian islands. This species is common on Alps and Apennines, while in the plains it is declining because of the loss. Competition with the grey squirrel and habitat fragmentation are considered the major threats to the survival of the red squirrel. The grey squirrel is present in and Liguria. A study on the Piedmontese colony showed that the red squirrel is disappearing from the area colonised by the grey squirrel and the damage due to bark-stripping and feeding is considerable. Free-ranging populations of the Siberian live in Belluno, Verona, and Rome, but records of single were reported for other areas. The Finlayson's squirrel is pre- sent with a small nucleus in an urban area of Piedmont. Here, the impact of this species on the veg- etation appears dramatic. The eradication of the grey squirrel is a priority for the conservation of the red squirrel, but control plans for the other are also needed. Key words: Red squirrel ( vulgaris), Grey squirrel (Sciurus carolinensis), ( sibiricus), Finlayson's squirrel ( finluysoni), alien species, Italy.

INTRODUCTION but other species have been introduced late- ly. These are: the grey squirrel (Sciurus car- The introduction of alien species is one of the olinensis) that was introduced into Piedmont greatest threats to native biodiversity, only the in 1948 and into Liguria in 1966; the Siber- destruction of habitat is worse. A UN report ian chipmunk (Tamias sibiricus) released in shows that 20% of the endangered vertebrate different sites of North and Central Italy; the species are so because of introduced species Finlayson's squirrel (Callosciurus fin- (Baskin, 1996). Furthermore, a lot of aliens laysoni) introduced into Acqui Terme (AL) may interact negatively with human activi- 16-18 years ago. The presence of the grey ties, thus causing a remarkable economic loss squirrel in Italy poses a serious conservation (Lever, 1994). The Convention on Biological problem: in fact this species competes with Diversity, adopted in 1992 by the summit in the native red squirrel and causes its disap- Rio de Janeiro, and signed also by Italy, rec- pearance. The first introduction into ognized these dangers and obliged all sub- of the grey squirrel occurred in scribing nations to prevent the introduction of in the late 19th century (Laidler, 1980; new species and to control or eradicate those Lloyd, 1983). In less than a century the alien already introduced, which proved to cause a squirrel has replaced the native one over threat to the ecosystems. most of the country (Reynolds, 1985; Ush- The red squirrel (Sciurus vulgaris) is the on- er et al., 1992; Gurnell and Pepper, 1993); ly squirrel species naturally present in Italy, the same is happening in Italy (Wauters et 66 S. Bertolino et al.

Table 1 - Presence of the red squirrel in different regions of Italy, differentiated in: widespread (+); localized (+I-); rare or absent (-). Data are taken from literature (, Valle d’Aosta: S.TE.P., 1994; Lombardia: Prigioni et al., in press; Venezia: Bon et al., 1995; Friuli: Lapini et al., 1996; Gros- seto: Sforzi and Ragni, 1997; Forli: Gellini et al., 1992; Marche: Pandolfi, 1992).

Area Alps Apennines Hills Plains

Valle d’Aosta +/- Piemonte + +I- Lombardia +/ - +/- Venezia +I- Friuli + Grosseto + + Forli +/- Marche + ? al., 1997b). Keeping in mind this situation em Italy, there is the subspecies S. v. merid- there is a growing concern about the possi- ionalis Lucifero, 1907, having the upper ble spread of the grey squirrel throughout parts of the body black and the lower parts the European continent. white. According to Cavazza (1913, in The aim of this paper is: (i) to point out the Cagnolaro, 1981) the body size increases status of the red squirrel and of the other in- gradually from the Alps to Calabria. troduced squirrels; (ii) to list the threats for The red squirrel was hunted until 1977 and the ecosystems where these species have was considered a pest to in the past been introduced; (iii) to supply information (Cagnolaro, 1981); nowadays this species is for the management of these species. protected by the Italian law (no. 157/92). Until now an organic research on the status RED SQUIRREL of the red squirrel in Italy is not available, (Sciurus vulgaris Linnaeus, 1758) but some information can be collected from atlases published locally (Table 1). The red squirrel has a Palaearctic distribu- In northern Italy this species is common on tion, from the Iberic peninsula to . Up Alps and pre-Alps, especially where there to date about 40 subspecies have been de- are mature and well grown forests, and it is scribed, but most of them are dubious. In present on most of the hills (S.TE.P., 1994; Italy three subspecies are present (Toschi, Bon et al., 1995; Lapini et al., 1996; Prigioni 1965), and the red squirrel is missing only in et al., in press). The situation in the plains is Salento (southern Apulia) and on the islands. different; here this species is endangered and On the Alps, and more generally north of the declining because of a high habitat fragmen- Apennines, one finds the subspecies S. vul- tation preventing the possibility of recoloni- garis fuscoater Altum, 1876, which is also sation when local extintion occurs. In Vene- widespread in Central Europe. The pelage tia and Friuli, the red squirrel is almost ab- colour goes from light red to dark brown, al- sent in the plains (Bon et al., 1995; Lapini et most black. In central Italy, north of Abruz- al., 1996), while in Piedmont and Lombardy zo, there is S. v. italicus Bonaparte, 1838, al- it still occupies some large lowland woods, ways having a light and a dark phase, but but local extinctions are common (Celada er less intensively pigmented. Finally, in south- al., 1994). The information on central and Squirrels in Italy 67

Table 2 - Tactics for conserving the red squirrel in Europe.

Management interventions useful to assure the survival of the red squirrel in Europe. a) Eradication of the grey squirrel from Italy.

Management interventions useful to favour colonisation by the red squirrel in areas presently not oc- cupied or dwelled in a non stable manner. a) Modification of the present forms of management so to obtain an increase of the wilderness of woods. b) In the plains, creation of ecological corridors to link isolated areas large enough (20- 40 ha) to host a source population. c) Application of re-iqtroduction or re-stocking programmes to favour the recoloniza- tion of suitable areas.

southern Italy is scanty. Gellini et al. (1992) rel (Celada et al., 1994; van Apeldoorn et consider this species common in almost all al., 1994, Verboom and van Apeldoorn, woods of the province of Forli (Romagna), 1990; Asferg et al., 1997). Wood size, pres- Sforzi and Ragni (1997) point out a positive ence of conifers, and nearby forests were trend and the colonization of new areas in positively correlated with the presence of the province of Grosseto (Tuscany), while the red squirrel. The distance from woods Pandolfi (1992) retains that the red squirrel bigger than 20-30 ha (where a source popu- is not present in all feasible environments of lation may be maintained) was negatively Marche. In any case, this species is absent correlated with the presence of this species: from some areas of Latium where there are an increasing distance decreased the chance apparently good ecologic conditions (e.g. Ci- to find a squirrel. In the only study made in mini Mounts in the province of Viterbo; Lep- Italy, Celada et al. (1994) pointed out the ini Mounts in the provinces of Rome, Latina presence of the red squirrel only in 28.3% and Frosinone; parts of the coast). The red of the 46 wood areas investigated in the Po squirrel can colonise urban areas, also of big Plain, These were near the rivers and cities, such as Rome (Cignini et al., 1997), Po, where there are still woods of a certain Bologna, Forli (Scaravelli and Di Girolamo, size. Normally red squirrels do not disperse 1998), Gorizia, Trieste and Udine (Lapini et over open , thus a landscape man- al., 1996), when they host forest remnants. agement must lead to the reduction of The red squirrel is considered an endan- woodland isolation. The connection between gered species in Europe (Amori and Zima, woodland fragments containing a “source” 1994; Mitchell-Jones et al., 1999) and in population (20-40 ha in size), could be in- Italy (Amori et al., 1993). The competition creased by planting hedgerows, treerows with the grey squirrel and habitat fragmen- and small woodland patches (Wauters et al., tation are considered the major threats to the 1994; Wauters, 1997). Other management survival of this species. At a regional scale, interventions useful to safeguard this species population dynamics are strongly af- (Table 2) may be the increase of tree species fected by woodland isolation (Andrtn, quality and reintroduction programmes in 1994). Research carried out in areas with a areas considered suitable for the red squir- different degree of habitat fragmentation en- rel (Fornasari et al., 1997; Wauters et al., abled to point out the factors which influ- 1997a). However, actions to favour the red enced the presence/absence of the red squir- squirrel will have a limited effect if the erad- 68 S. Bertolino et al.

in the town park (Currado et al., 1997). These animals came from an importer of Varese who had bought about 20 individuals from a Dutch importer, the rest of the ani- mals had been sold to private customers of whom the importer said not to have kept any reference. A part of the squirrels of , which had reproduced in the meantime, have been captured by the local sanitary unit and given back to the importer (!). This species was still reported in 1997 at Trecate and it is probably present in the nearby Ticino Natur- al Park. The grey squirrel can be found in Liguria, where 5 individuals coming from Norfolk (Virginia) were introduced in 1966 into the park of Villa Groppallo at Genoa Nervi (Fig. 1) (Capocaccia Orsini and Doria, 1991). A survey in 1994 enabled to record the presence of this species also in the near- Figure 1 - Distribution of Sciurus carolinensis in by towns of S. Ilario and Bogliasco (Oliva, Italy. UTM 50 km grid. Black circle: established 1995). Both in Piedmont and in Liguria, population; empty cirle: colony partially re- monitoring programmes are in progress with moved. the technique of hair-tubes, so to determine precisely the actual territory occupied by this species (Bertolino et al., 1998; Marsan, pen. ication of the grey squirrel will not take comm.). place soon (Table 2). The grey squirrel has a strong negative im- pact on the natural habitats and on agricul- GREY SQUIRREL tural activities. In Great Britain its diffusion (Sciurus carolinensis Gmelin, 1788) is causing the progressive disappearance of the red squirrel, which is presently exclu- This is a nearctic species, naturally present sively restricted to pure conifer forests of in the eastern part of . Its dis- Scotland and other few areas (Reynolds, tribution has increased after the introductions 1985; Usher et al., 1992; Gurnell and Pep- into Great Britain (Middleton, 1930; Laidler, per, 1993). Such a phenomenon is happening 1980; Lloyd, 1983; Gurnell, 1987), South also in Italy (Wauters et al., 1997b); so the (Lever, 1985), and Italy (Currado et competitive exclusion between both species al., 1987). The first introduction into Italy would be confirmed. The impact of the grey took place in Piedmont (northwestern Italy) squirrel is negative also for agro-forestal ac- (Fig. 1) in 1948, when two couples of grey tivities. In Great Britain this causes squirrels coming from Washington D.C. heavy damage to forests and tree commercial were released at Candiolo () (Currado plantations, because of bark-stripping on et al., 1987). Presently this species occupies beech and plants (Rowe and Gill, an area of about 450 km2 in the provinces of 1985; Kenward et al., 1992). In Piedmont, Turin and Cuneo (Bertolino, unpublished da- damage to poplars, hornbeams and cereal ta). Always in Piedmont, at Trecate crops have been recorded (Currado et al., (province of ), the townhall intro- 1987; Currado, 1993). duced in 1994 three couples of grey squirrels The mechanisms which make the grey Squirrels in Italy 69 squirrel replace the red one are not yet clear tained in grey squirrel populations and and several hypotheses have been suggest- transmitted lethally to red squirrels. The ed (Gurnell, 1987; Gurnell and Pepper, risks connected to the presence of the grey 1993; Kenward and Holm, 1993; Skelcher, squirrel in Italy are plenty. If the popula- 1997). The most probable explanation tions present in Piedmont and Liguria reach seems linked to the higher competitivity of the Alps and the Apennines, an expansion the grey squirrel in the exploitment of envi- of this species to the rest of Europe would ronmental resources, especially in broadleaf be unavoidable, with a serious danger for and mixed woods. The grey squirrel weighs the survival of the red squirrel and a dra- in average the double of the red squirrel matic economic impact on agriculture. In (Gurnell, 1987, 1991a, 1991b) and it can in- consideration of these problems, the Italian crease its weight in of about 20%, Wildlife Institute has started an experimen- while the red squirrel has an increase of tal intervention project with the co-opera- 10% (Kenward and Tonkin, 1986). More- tion of the . Such a pro- over, Kenward and Holm (1993) proved ject was blocked in 1997 by a report to the that the grey squirrel is thus able to exploit court made by an animal rights group. better the autumn stock of with a high energy content produced by broadleaf trees, SIBERIAN CHIPMUNK increasing its reserves, which are useful (Tamias sibiricus Laxmann, 1769) to pass winter. The red squirel, instead, is more vulnerable to food shortage periods. A This is a small semi-terrestrial squirrel, with greater weight in autumn does not help on- a natural distribution comprising the forest ly to pass winter, but increases also the re- regions of northern Eurasia, eastern productive success (Wauters and Dhondt, and the countries on the White Sea; it ar- 1989a, 1989b; Wauters et al., 1993; Gurnell rives southwards to the Altai Mounts and 1996). Effectively, in the broadleaf woods northern (Niethammer and Krapp, the grey squirrel may reach a density of 2- 1978). Naturalized colonies derived from es- 8 animals per ha, while the red squirrel caped animals have become established in does not generally go over 1 animal per ha; , , , , Nether- in conifer woods the density of both species lands and (Niethammer and is equal to about 1 animal per ha (Gurnell, Krapp, 1978; Lever, 1985; Fernandez, 1987, 1991a, 1991b). In any case, the pres- 1995). In Italy (Fig. 2), free-ranging popu- ence of some broadleaf trees (even < 1%) lations are found in Belluno, Verona, and in the conifer woods permits the stable Rome (Amori and Gippoliti, 1995; Dal Far- presence of the grey squirrel (Smith and ra et al., 1996). Other records of T sibiricus Gurnell, 1997), favouring the replacement were reported for Bolzano, Genoa, Padua, of the red squirrel in the long term. Re- Trino Vercellese, and Udine (Currado et al., cently, Wauters (1998) found out a lower 1987; Dal Farra et al., 1996), but it is prob- survival rate in young red squirrels if grey able that some individuals have been re- squirrels are present, such a factor would be leased alsojn other sites. The colony of Bel- determinant in the replacement between luno came from several animals which had these squirrels. The possible influence of escaped from a big importer and presently it diseases on population dynamics of red has occupied an area of 5-6 km along the squirrels, already hypothesized in the past river Piave (Dal Farra et al., 1996). The area (Keymer, 1983), has had lately more con- where this species is present includes the firmations. It seems in fact that a Parapox river woods and the surrounding areas with virus, identified in both species (Duff et al., meadows and cultivations alternated with 1996; Sainsbury et al., 1997), may be main- woodlots and hedges (Dal Farra et al., 70 S. Bertolino et al.

U

Figure 2 - Distribution of Tamias sibiricus in Figure 3 - Distribution of Callosciurus~nlaysoni Italy. UTM 50 km grid. Black point: individuals; in Italy. UTM 50 km grid. Black circle: estab- black circle: established population. lished population.

1996). No interaction of Tamias sibiricus were released in a 2 ha park at Acqui Terme with other species is known; both in Belluno (Alessandria) 16-18 years ago (Fig. 3). and in Rome this species co-exists with Sci- Presently there are about fifty animals urus vulgaris, apparently without giving ori- which seem still concentrated in the original gin to interspecific competition (Amori and release area (Bertolino and Mazzoglio, un- Gippoliti, 1995; Dal Farra et al., 1996). published data). The size and colour corre- However this species should be eradicated spond to those of a population present in as a safety measure. Thailand in the region of Thonburi north of Ayutthaya and belonging to the subspecies FINLAYSON’S SQUIRREL C. finlaysoni bocourti (Milne-Edwards, (Callosciurus finlaysoni Horsfield, 1823) 1867), according to Corbet and Hill (1992). The impact of this species on the vegetation This is present in Burma, Thai- of the park of Acqui Terme appears consid- land, Laos, Cambogia and South Vietnam. erable, a lot of old trees show vast barkstrip- Its pelage is extremely variable, therefore it ping, sometimes so wide to compromise is also called variable squirrel. The pelage their survival (Bertolino et al., in press). may be black, red, white, or show parts with Such a phenomenon could be due to the high a different colour. Corbet and Hill (1992) concentration of animals, or correspond to a identified sixteen subspecies. In the areas of typical behaviour of this species, maybe en- origin, the Finlayson’s squirrel has been hanced by the presence in a habitat different recorded in different forest habitats, includ- from the originary one. Lever (1985) reports ing dense forests, thin woods and coconut on a similar behaviour shown by Callosciu- plantations (Lekagul and McNeely, 1988). rus caniceps, which was introduced in the Two couples of the Finlayson’s squirrel ‘40s in Japan. The same author reminds how, Squirrels in Italy 71 in a few decades, from some animals es- provocati da Sciuridae alloctoni in- caped from a zoo, a population of about trodotti in Italia. I1 Congresso Nazionale 20000 animals had taken origin. Bark-strip- di Selvicoltura, Venezia, 24-27 giugno ping is reported also for Callosciurus ery- 1998. thraeus (Kuo et al., 1982; Zhu et al., 1990). Bertolino, S., Currado, I., Mazzoglio, P.J. At present it is not possible to evaluate with and Pallavicino, L., 1998. L‘uso degli certainty what will be the impact of C. fin- hair-tubes nel monitoraggio di roditori laysoni once that it reaches the hills around arboricoli. I1 Congresso Italian0 di Teri- Acqui Terme. Considering what happened in ologia, Varese, Abstract book: 172. Japan with C. caniceps and the impact that Bon, M., Paolucci, F., De Battisti, R. and C. finlaysoni may have on the vegetation, its Vernier, E. (eds.), 1995. Atlante dei diffusion must be absolutely avoided. Mammiferi del Veneto. Lavori SOC.Ven. Sc. Nat., (n.s.) 21: 60. Cagnolaro, L., 1981. Scoiattolo Sciurus vul- garis Linnaeus, 1758. In: AA.VV. Dis- REEFERENCES tribuzione e biologia di 22 specie di Mammiferi in Italia. Progetto finalizzato Amori, G., Angelici, EM., Frugis, S., Gan- “Promozione della qualitb dell’ambiente”, dolfi, G., Groppali, R., Lanza, B., Reli- AQ/1/142-164, CNR Roma: 27-30. ni, G. and Vicini, G., 1993. Vertebrata. Capocaccia Orsini, L. and Doria, G., 1991. In: Minelli, A., Ruffo, S. and La Posta, L‘utile, il dilettevole, il clandestino: la S. (eds.), Checklist delle specie della fauna europea si trasforma. In: Capocac- fauna italiana, 110. Calderini, Bologna. cia Orsini, L., Doria, G. and Doria, G. Amori, G. and Gippoliti, S., 1995. Siberian (eds.). 1492-1992: Animali e piante dalle chipmunk Tamias sibiricus in Italy. Americhe all’Europa. SAGEP Editrice, Mammalia, 5 9( 2) : 28 8-289. Genova: 33-63. Amori, G. and Zima, J., 1994. Threat- Celada, C., Bogliani, G., Gariboldi, A. and ened in Europe: species sta- Maracci, A., 1994. Occupancy of isolat- tus and some suggestions for conser- ed woodlots by the red squirrel Sciurus vation strategies. Folia Zoologica, vulgaris L. in Italy. Biological Conser- 43(1): 1-9. vation, 69: 177-183. Andrtn, H., 1994. Effect of habitat frag- Cignini, B., Cristaldi, M. and Sartoretti, A., mentation on and in 1997. Lo Scoiattolo Sciurus vulgaris L., landscape with different proportion of 1758 nella cittb di Roma. Ecologia Ur- suitable habitat: a review. Oikos, 71: bana, 9(2-3): 14-15. 355-366. Corbet, G.B. and Hill, J.E., 1992. The mam- Asferg, T., Moller Nielsen, S., Rosengaard, mals of the Indomalayan region: a sys- M. and Bertelsenn, J., 1997. Presence/ab- tematic review. Natural History Museum sence of red squirrel Sciurus vulgaris in publications, Oxford University Press. Danish woodlots: demonstration of frag- Currado, I., 1993. Lo scoiattolo grigio amer- mentation effects. I11 European Squirrel icano (Sciurus carolinensis Gmelin), Workshop, Bavaria, Germany. nuovo nemico per l’arboricoltura da leg- Saugetierkundliche Informationen, 21. no in Italia (Rodentia: Sciuridae). Con- Baskin, Y., 1996. Curbing undesirable in- vegno Arboricoltura da legno e politiche vaders. BioScience, 46( 10): 732-736. comunitarie, Tempio Pausania: 85-94. Bertolino, S., Currado, I., Mazzoglio, P.J. Currado, I., Scaramozzino, P.L. and Brussi- and Vaiana, M., (in press). Danni a no, G., 1987. Note sulla presenza dello impianti per l’arboricoltura da legno Scoiattolo grigio (Sciurus carolinensis 72 S. Bertolino et al.

Gmelini, 1788) in Piemonte (Rodentia: Gurnell, J., 1996. The effects of food avail- Sciuridae). Ann. Fac. Sci. Agr. Univ. ability and winter weather on the dy- Torino, 14: 307-33 1. namics of a grey squirrel population in Currado, I., Mazzoglio, P.J., Amori, G. and southern England. Journal of Applied Wauters, L., 1997. Rischi biologici delle Ecology, 33: 325-338. introduzioni: il caso dello Scoiattolo gri- Gurnell, J. and Pepper, H., 1993. A critical gio (Sciurus carolinensis Gmelin, 1788) look at conserving the British red squir- in Italia. In: Spagnesi, M., Toso, S. and rel Sciurus vulgaris. Mamm. Rev., 23: Genovesi, P. (eds.). Atti del I11 Conveg- 125-136. no Nazionale dei Biologi della Selvaggi- Kenward, R.E. andTonkin, J.M., 1986. Red na. Suppl. Ric. Biol. Selvaggina, 27: and Grey squirrels: some behavioural 277-284. and biometric differences. J. Zool. Dal Farra, A., Cassol, M. and Lapini, L., Lond., 209: 279-28 1. 1996. Status del Burunduk (Tamias Kenward, R.E. and Holm, J.L., 1993. On the sibiricus [Laxmann, 17691, Rodentia, replacement of the red squirrel in Sciuridae) nel Bellunese (Italia Nord- Britain: a phytotoxic explanation. Pro- Orientale). Boll. Mus. civ. St. nat., ceedings of the Royal Society of London Venezia, 45 (1994): 189-193. B, 251: 187-197. Duff, J.P., Scott, A. and Keymer, I.F., Kenward, R.E., Parish, T. and Robertson, 1996. Parapox virus infection of the P.A., 1992. Are tree species mixtures too grey squirrel. Mammal News, The good for grey squirrel? In: Cannel, Quaterly Newsletter of the Mammal M.G.R., Malcolm, D.C. and Robertson, Society: 10. P.A. (eds.). The ecology of mixed Fernandez, H., 1995. Tamias sibiricus (Lax- species stands of trees. Blackwell Scien- mann, 1769). In: AA.VV. Mammiferi tific Publishers, Oxford: 243-253. della Svizzera. Distribuzione, biologia, Keymer, I.F., 1983. Diseases of squirrels in ecologia. Birkhauser Verlag, Basel- Britain. Mammal Review, 13: 155-158. Boston-Berlin: 236-238. Kuo, P.C., Kao, C., Liu, C.F. and Hwang, Fornasari, L., Casale, P. and Wauters, L.A., ED., 1982. Correlation of the damage by 1997. Red squirrel conservation: the as- Formosan red-bellied squirrel with sessment of a reintroduction experiment. chemical composition of wood: Part 111. Ital. J. Zool., 64: 163-167. Sugar content of bark. Memoirs of the Gellini, S., Casini, L. and Matteucci, C. (eds.), College of Agriculture National Taiwan 1992. Atlante dei mammiferi della Provin- University, 22(2): 25-36. cia di Forli. Maggioli Editore, 179 pp. Laidler, K., 1980. Squirrels in Britain. David Gurnell, J., 1987. The natural history of & Charles, North Pomfret, 192 pp. Squirrels. Christopher Helm, London, Lapini, L., Dall’Asta, A., Dublo, L., Spoto, pp. 201. M. and Vernier, E., 1996. Materiali per Gurnell, J., 1991a. The red squirrel. In: Cor- una Teriofauna dell’Italia Nord-orientale bet, G.B. and Harris, S. (eds.). The (Mammalia, Friuli-Venezia Giulia). Gor- Handbook of British Mammals. Black- tania, Atti del Museo Tridentino di Sto- well Scientific Publications, Oxford: ria Naturale, 17 (1995): 149-248. 176-186. Lekagul, B. and McNeely, J.A., 1988. Mam- Gurnell, J., 1991b. The grey squirrel. In: mals of Thailand. Darnsutha Press, Corbet, G.B. and Harris, S. (eds.). The Bangkok, 759 pp. Handbook of British Mammals. Black- Lever, C., 1985. Naturalized mammals of well Scientific Publications, Oxford: the world. Longman, London and New 186-191. York, 497 pp. Squirrels in Italy 73

Lever, C., 1994. Naturalized animals. T. and Scaravelli, D. and Di Girolamo, A,, 1998. AD. Poyser Natural History, London, La colonizzazione delle citth romagnole 354 pp. da parte di Sciurus vulgaris L., 1758. In: Lloyd, H.G., 1983. Past and present distrib- Bologna, M.A., Carpaneto, G.M. and ution of red and grey squirrels. Mammal Cignini, B. (eds.). I” Convegno sulla Review, 13: 155-158. Fauna Urbana, Fratelli Palombi Editori: Middleton, A.D., 1930. The ecology of the 233-234. American grey squirrel in the British Skelcher, G., 1997. The ecological replace- Isles. Proceedings of the Zoological So- ment of red by grey squirrels. In: Gur- ciety of London, 809-843. nell, J. and Lurz, P. (eds.). The Conser- Mitchell-Jones, A.J., Amori, G., Bogdanow- vation of Red Squirrels, Sciurus vulgaris icz, W., KryStufek, B., Reijnders, P.J.H., L. People Trust for Endangered Species: Spitzenberger, F., Stubbe, M., Thissen, 67-78. J.B.M., Vohralik, V. and Zima, J., 1999. Sforzi, A. and Ragni, B., 1997. Atlante dei The Atlas of European Mammals. The Mammiferi della provincia di Grosseto. Academic Press, London. 496 pp. Atti Museo di Storia Naturale della Niethammer, J. and Krapp, E, 1978. Hand- Maremma, n. 16 (suppl.). buch der Saugetiere Europas. Band 2/I: Smith, D. and Gurnell, J., 1997. The ecolo- Rodentia 11. Akademische Verlagsge- gy of the grey squirrel, Sciurus caroli- sellschaft, Wiesbaden: 116-121. nensis, in conifer forest. In: Gurnell, J. Oliva, E., 1995. Lo Scoiattolo grigio (Sciu- and Lurz, P. (eds.). The Conservation of rus carolinensis Gmelini, 1788) in Lig- Red Squirrels, Sciurus vulgaris L. People uria: problematiche di una reintro- Trust for Endangered Species: 109-1 19. duzione. Graduation Thesis, University S.TE.P. (Stazione Teriologica Piemontese), of Genoa, 84 pp. 1994. Progetto Atlante Mammiferi Pandolfi, M., 1992. Fauna nelle Marche. Piemonte - Valle D’Aosta. Dati a1 Mammiferi e Uccelli. Regione Marche, 3 1/05/93. Unpublished report. I1 Lavoro editoriale, 133 pp. Toschi, A., 1965. Fauna d’Italia VII. Mam- Prigioni, C., Cantini, M. and Zilio, A., (in malia: Lagomorpha, Rodentia, Carnivo- press). Atlante dei Mammiferi della ra, Ungulata, Cetacea. Calderini, Lombardia. Regione Lombardia. Bologna, 647 pp. Reynolds, J.C., 1985. Details of the geo- Usher, M.B., Crawford, T.J. and Banwell, graphic replacement of the red squirrel J.L., 1992. An American Invasion of (Sciurus vulgaris) by the grey squirrel Britain: The Case of the Native and (Sciurus carolinensis) in eastern Eng- Alien (Sciurus) species. Conservation land. J. Anim. Ecology, 54: 149-162. Biology, 6: 108-1 15. Rowe, J.J. and Gill, M.A., 1985. The suscep- Van Apeldoorn, R.C., Celada, C. and tibility of tree species to bark-stripping Nieuwenhuizen, W., 1994. Distribution damage by grey squirrels (Sciurus caroli- and dynamics of the red squirrel (Sciu- nensis) in England and Wales. Quaterly rus vulgaris L.) in a landscape with frag- Journal of Forestry, 79: 183-190. mented habitat. Landscape Ecology, 9: Sainsbury, A.W., Nettleton, P. and Gurnell, 227-235. J., 1997. Recent developments in the Verboom, B. and van Apeldoorn, R.C., study of parapoxvirus in red and grey 1990. Effects of habitat fragmentation on squirrels. In: Gurnell, J. and Lurz, P. the red squirrel, Sciurus vulgaris L. (eds.). The Conservation of Red Squir- Landscape Ecology, 4: 171-176. rels, Sciurus vulgaris L. People Trust for Wauters, L., 1997. The ecology of red squir- Endangered Species: 105- 108. rels (Sciurus vulgaris) in fragmented 74 S. Bertolino et al.

habitats: a review. In: Gurnell, J. and Wauters, L.A., Casale, P. and Dhondt, A.A., Lurz, P. (eds.). The Conservation of Red 1994. Space use and dispersal of red Squirrels, Sciurus vulgaris L. People squirrels in fragmented habitats. Oikos, Trust for Endangered Species: 5-12. 69: 140-146. Wauters, L., 1998. La competizione inter- Wauters, L.A., Casale, P. and Fornasari, L., specifica tra scoiattolo grigio e scoiatto- 1997a. Post-release behaviour, home lo rosso in Italia. I1 Congress0 Italian0 di range establishment and settlement suc- Teriologia, Varese, Abstract book: 8. cess of reintroduced red squirrels. Ital. J. Wauters, L.A. and Dhondt, A.A., 1989a. ZOO^., 64: 169-175. Variation in length and body-weight of Wauters, L.A., Currado, I., Mazzoglio, P.J. the red squirrel (Sciurus vulgaris) in two and Gurnell, J., 1997b. Replacement of different habitats. Journal of Zoology, red squirrels by introduced grey squirrels 217: 93-106. in Italy. In: Gurnell, J. and Lurz, P. Wauters, L.A. and Dhondt, A.A., 1989b. (eds.). The Conservation of Red Squir- Body weight, longevity and reproductive rels, Sciurus vulgaris L. People Trust for success in red squirrel (Sciurus vul- Endangered Species: 79-88. garis). J. Anim. Ecol., 58: 637-651. Zhu, Y., Zhang, W. and Zhu, X., 1990. Bark- Wauters, L.A., Bijens, L. and Dhondt, A.A., stripping damage to forest trees by red- 1993. Body mass at weaning and juve- bellied tree squirrel (Callosciurus ery- nile recruitment in the red squirrel. J. thraeus) in Zhejiang Province. Acta The- Anim. Ecol., 62: 280-286. riologica Sinica, lO(4): 276-281,