What is a native species?

It is a species that is naturally present within a given geographical range where it originated or arrived without the direct intervention (whether intentional or not) of man.

What is an alien species?

It is a species that does not belong to the original flora or fauna of a given geographical area, but which was introduced there (intentionally or not) by man.

What is an invasive alien species?

It is an exotic species whose introduction and/or expansion constitutes a threat to biological diversity.

Where do Yelkouan Shearwaters live and what are their ecological characteristics?

The Yelkouan Shearwater (Puffinus yelkouan) is a pelagic bird that nests on rocky coasts and islands. During the non-breeding season they disperse throughout the Mediterranean and the Black Sea, often forming large storms. At least seven colonies went extinct in recent decades, probably due to predation on the part of Black Rats, which are the main threat to this species.

Why is Caprobrotus spp. a threat for protected habitats?

The genus Caprobrotus comprises several plant species that are native to South Africa. They are found all along the Italian coast, were they were introduced for ornamental purposes and in order to stabilize sand dunes. They can form thick, impenetrable mats 20 cm wide and 50 cm deep and aggressively compete with native species. They can change the nature of the soil by lowering its pH balance and altering soil nutrients.

What are the ecological characteristics, the place of origin, and the current distribution of the Black Rat?

Black Rats are Asian in origin; according to some authors, their original range was south-east Asia, while others believe it was the Indian subcontinent. They are though to have been introduced to Italy in paleontological times; the earliest evidence of its presence in Italy comes from Sardinia and is estimated to be about 5,000 years old. They easily adapt to a great variety of habitat, and can live in close contact with humans as well as in more remote areas. Black Rats have been proven to have a negative impact on plant life and on vertebrate and invertebrate fauna both on islands and in continental areas. They can prey on the eggs and nestlings of both ground-nesting and tree-nesting birds. The presence of Black Rats on islands can also contribute to high population densities of native predators such as gulls.

What are the possible causes of the alien species introduction?

In Italy, the presence of alien species can be traced to three main factors: accidental introduction, introductions aiming to obtain established populations of exotic species, and escapes from captivity. With regards to the latter, some species were introduced to Italy in order to be farmed for fur or meat, while others were imported for ornamental purposes and were either voluntarily released into the wild or escaped from captivity. Other species are introduced for hunting purposes, in which case they are voluntarily released into the wild, sometimes in large numbers. In some cases the introduced species are quite closely related to native species, leading to the risk of hybridization and genetic pollution. A final category of alien species includes those introduced into other countries which autonomously colonized Italy (secondary introduction).