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Mammalia 73 (2009): 169–202 ᮊ 2009 by Walter de Gruyter • Berlin • New York. DOI 10.1515/MAMM.2009.029
Review
Mammals of the Mediterranean islands: homogenisation
and the loss of biodiversity
Marco Masseti ical and archaeozoological evidence demonstrates that
several of the fossil and subfossil island faunas differed
Dipartimento di Biologia Evoluzionistica ‘‘Leo Pardi’’ considerably from contemporary continental faunas, and
dell’Universita` di Firenze, Laboratori di Antropologia ed were characterised by a very low taxonomic diversity
Etnologia, Via del Proconsolo, 12 – 50122 Firenze, Italy, (Azzaroli 1971, 1977, Sondaar 1971, 1977). The great
e-mail: marco.masseti@unifi.it number of islands in the Mediterranean made this region
highly favourable to the evolution of island endemics
Abstract (Sondaar and Boekschoten 1967, Dermitzakis and Son-
daar 1978, Kotsakis et al. 1980, Sondaar et al. 1986,
There is possibly no other location in the world which has Marra 2005). Examples from the Balearics, Corsica and
been so intensively influenced by human activity over a Sardinia, the Tuscan archipelago, Capri, Sicily, Malta,
prolonged period as the Mediterranean. Virtually no eco- Crete, many Aegean islands, and Cyprus are significant
systems have been left untouched. Since prehistory, the (Azzaroli 1971, 1977, Sondaar 1971, 1977, Vigne 1992,
human settlers of the Mediterranean islands brought Masseti and Mazza 1996) (Figure 1). From a biogeo-
about a radical turnover between ancient and modern graphical point of view, all these insular territories have
mammalian faunas, introducing a variety of allochtho- to be regarded as ‘‘oceanic islands’’ (cf. Wallace 1876,
nous continental taxa. The data available for the Medi- Ghigi 1950, Dermitzakis and Theodorou 1994). In effect,
terranean islands point to endemic mammalian extinction within the Mediterranean basin it is almost impossible to
being largely the result of human activities of land clear- ascertain the existence of islands of an authentically
ance and the introduction of allochthonous animals. ‘‘oceanic type’’, which is the term generally adopted to
Today, this fauna is no longer characterised by the indicate volcanic islands formed independently of conti-
majority of the endemic mammals previously reported. nental land masses. In conceptual terms, oceanic islands
It displays virtually the same species composition, being are indeed the opposite of ‘‘continental islands’’, the lat-
almost exclusively characterised by continental ter being territories that are instead close to a continental
mammals whose appearance on the islands has essen- landmass, and geologically related to it, having been
tially been influenced by man, and dominated by gener- formed by separation from the nearest mainland (cf.
alist species. The invasion of ecosystems by exotic taxa Lincoln and Boxshall 1987). Perhaps it would be more
is currently viewed as one of the most important causes precise to refer to them as ‘‘oceanic-like islands’’ (cf.
of the loss of biodiversity. Today, in view of the vulnera- Alcover et al. 1998), or genuinely ‘‘true islands’’, which is
bility of the insular ecosystems it is critically important to an expression used to designate insular territories that
prevent further introductions. But this results in the ques- have been separated from the closest mainland for a very
tion of how to treat the allochthonous mammalian pop- long time, since at least the beginning of the Upper Pleis-
ulations of certified ancient anthropochorous origin, tocene (Vigne 1999, cf. Gorman 1979). Addressing the
which instead deserve to be protected and considered in obvious difficulties faced by most organisms in trying to
terms of a veritable ‘‘cultural heritage’’. Moreover, their cross salt water, biogeographers used to postulate that
protection and their study can provide an opportunity for most remote islands were once linked to continents by
testing a range of different evolutionary theories. land-bridges now sunk from view (Gorman 1979). It is in
fact commonly assumed that, before becoming dwarfed,
Keywords: anthropochorous mammals; endemic many of the Mediterranean macromammals reached the
faunas; generalist species; Holocene; Mediterranean islands from the mainland via temporary land-bridges
islands; Upper Pleistocene. that originated as a result of the lowering of the sea level
during glacial episodes. According to Azzaroli (1971,
Introduction 1977, 1983), this may have happened in Sardinia and
Sicily. On the basis of tectonic factors, Malatesta (1980)
The Mediterranean shores have always offered a unique observes that Crete may also have been joined to con-
range of peculiar biological elements. Amongst these, it tinental Greece during the Pleistocene. However, as not-
may be interesting to recall the former existence of ed by Davis (1987), it is then difficult to explain why the
endemic insular mammals. In fact, the late Quaternary Pleistocene faunas of the latter islands are relatively rich
island ecosystems were quite different in some ways compared to that of Cyprus. It may be that only a few
from the adjacent continental ecosystems. Palaeontolog- species migrated to this eastern Mediterranean island,
which was somewhat more difficult to reach (cf. Azzaroli
1977).
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