We review and update available information on the population size and
distribution of Cory's Shearwater, Calonectris diomedea, and Yelkouan Shearwater,
Puffinus yelkouan, in Italy. More than 90% of the population of these species rely on 64
islands, but the former breeds on twice as many islands as the latter. Some cases of local
extinction were recorded. The analysis of distributions, along with that of island features
and presence of rats, showed inter-specific differences. The Yelkouan Shearwater
tends to occupy larger and more offshore islands than the other species does. It's the
only one that shows a clear positive correlation between abundance and island size.
Finally, it is not present in rat-free islands, with a single exception of no quantitative
relevance. Available data on the breeding success of both species are presented; complete
failures where rats occur were recorded. Operations of rat control or eradication are
presented and their consequences on seabirds' breeding success commented