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particularly the presence ofnative mammals in the Pleistocene. Por instance, in the
Sardo-Corso Massif, paleo-introduced ungulates can have a positive role in the
ecosystem through a moderatevegetation disturbance (Verdù et al., 2000). On the
contrary, in oceanic islands like Formentera and Zannone, which never had
autochthonous ungulates, endemie plants could suffer from the introduction of
ungulates because of the absence of any adaptation to protect them from grazing

(Bowen and Van Vuren, 1997). While the impact of species such as Rattus rattus

on colonial nesting sea birds is well known (Thibault, 1995), the effects on other
components ofisland biodiversity is generally less appreciated. In the Balearic islands,
Mallorca and Minorea, introduced carnivores caused the extinction ofthe endemie

lizard Podarcispityusensis, and, as consequence, causing a ehange in seed dispersion
of the endemie plant Cneorurn triccon (Riera et al., 2002). Comparing the

tenebrionid fauna of 51 islets of the Balearic, Palmer and Pons (1996) found that
the presence of rats, while increasing the extinction rate of endemie tenebrionid
species, does not alter the total number of species due to replacement by non-
endemie, synantropic species.

Abundance of'exotic' preys on islands has been proved to cause the possible
extinction ofendemie taxa. In a Californian island, the presence offeral pigs lead
to the establishment ofgolden eagles and the reduction ofan endemie fox preyed
upon by the eagles (Roemer et al., 2002). This case offers a model to explain the
almost total extinction of small palaeoendemic mammals in the Mediterranean

islands- the only exceptions being two species ofshrews of the genus Crocidura,

usually not considered edible by mammalian predators. On the other hand,
modern instùar mammals had a key role in maintaining poptùation ofcharismatic

species such as birds ofprey (see for example Bonelli's eagle, Hieraaetusfasciatus,

Arroyo and Ferreiro, 2001). This may create a conflict between protection of
birds of prey - another group of great interest for conservationists and the
safeguard of neglected groups such as invertebrates or plants.

Less than 20 years ago, a group of mammalogists discussing the status of
Mediterranean mammals, identified the monk seal, the Corsican red deer, the
fallow deer and the otter, as four conservation priorities for insular mammals
(Cheylan, 1988). Nowadays, more data and the awareness of the need to direet
our efforts toward truly insular endemie species, allow us to compite a more
rigorous set ofpriorities induding:
a) paleoendemic taxa, such as the monk seal and the Cretan white-toothed shrew

Crocidura zirnrnerrnanni;

b) island populations whose present distribution is unlikely to have been

mediated by humans, such as Talpa stankovici on Corfu and the snow vale
Chionornys nivalis on Euboea;

c) bats, especially populations of Crete and of the Sardo-Corso Massif.

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