MASS KILLS OF GREAT CORMORANTS Phalacrocorax carbo
IN WESTERN SARDINIA

Nicola Baccetti

The lagoon system surrounding the town of Oristano, W Sardinia, hosted in recent years the largest Great Cormorant Phalacrocorax carbo flocks to be observed in Italy. Despite its relatively small size, at least compared to N Adriatic lagoons, in the winter of 1995/96 Oristano reached the top figure of some 15,000 cormorants concentrated on ca. 7,500 ha of potential feeding area for the species (excluding the sea, where birds did not forage regularly). Almost all coastal lakes are independent from each other and connected to the sea by artificially regulated canals, according to the needs of traditional and economically important Grey Mullet fisheries (mainly involving Liza species). The lakes are state property and mostly Ramsar sites. Fish is collected by professional fisherman groups, each one having the exclusive rights of exploitation of a single lagoon. Contrary to the Adriatic 'valli', natural inflow of fish-fry from the sea is large enough to obtain a profitable economic balance to the fishing activities. Thus, fishing indeed represents an important income and occupational source for the villages around Oristano, and competition with the cormorants was therefore felt as a serious socio-economic problem by a large fraction of the local human population.

This is, very basically, the background situation which motivated politicians (after much campaigning in newspapers, occupation of Cagliari regional headquarters by fishermen, etc.) to authorise Great Cormorant shooting in Oristano. After a trial conducted late in the previous wintering season (February 1995: less than 200 birds officially shot), hostilities were resumed at the start of December 1995 and lasted till about the end of the month. The authorisation by the regional administration had arbitrarily fixed a limit at 1,500 birds (10% of the initial population size), despite the different opinion of INFS - the national advisory agency for wildlife issues. The latter had suggested to limit shooting to a few individuals as an additional disturbance measure to be addressed only to socially foraging flocks at the very start of the winter, and not at roosts. This strategy would not so much have aimed at reducing bird numbers directly, but rather at reducing the availability of suitable feeding areas. It was thought that in this way the juvenile fraction of the population would eventually be forced to resume migration before site fixation to winter quarters had occurred. Indeed, this was apparently the case: in spite of the fact that 'only' some 700 birds were officially shot in about 20 days on feeding sites, roosts and wherever it was possible, the overall population had decreased from 15,000 to about 5,000 at the end of the same period, apparently with no parallel increase in the rest of Sardinia. There are claims of a common grave dug somewhere in the saltmarshes, to hide additional corpses collected when guards were absent. This may be true, but it still seems very unlikely, that illegal kills would have exceeded legal ones and after the end of the shooting period only single birds may have been illegally killed. Thousands of Great Cormorants, therefore, were missing in the second count, and did not re-appear during the whole course of the winter, suggesting they moved elsewhere.

Shooting was forbidden once it was realised that only 5,000 birds remained in the area, a figure which had been tolerated by the fishermen in the past when it naturally occurred. The Christmas tree in the main square of Cabras, one of the fishermen villages, was promptly decorated with cormorant cutouts (and maybe rings too!). Most corpses (500) were examined, sexed and measured by a team led by Giuseppe Cherubini, who managed to transform mid-winter holidays in the wonderful Sardinian countryside into a quite unpleasant job. Only a part of the stomachs has been examined so far, the rest still lays inside the INFS freezers... waiting for time, money and people wishing to open them. Censuses were conducted by observers belonging to IVRAM and Molenargius Association, under the coordination of Helmar Schenk.

Comments on this operation are not easy, particularly in view of its probable recurrence in future seasons. Some negative consequences are quite important. I shall mention three of them.

* Additional mortality in flocks of wintering Great Cormorants: beside kills and birds which probably left the area, the remaining ones were in poor physical conditions. Fat reserves were large in birds shot in the early days, and totally absent in samples from the end of the period, when most birds had to spend much time foraging at sea or unsuccessfully attempting to move to the lagoons.

* Threat to the relict Sardinian colony of Great Cormorants: these birds breed quite close to the lagoons and were at risk to be shot together with non-local birds.

* Disturbance to other waterfowl: nobody counted birds - apart from cormorants - on the lagoons before the start of shooting, but I personally saw huge Pochard Aythya ferina flocks and the usual Greater Flamingo Phoenicopterus ruber numbers in early December, which I could not find again among the results of the following mid-January counts. Indeed, there are no reasons why, if Great Cormorants left the area, other species should not have done the same, as - beside shooting - disturbance was created in all possible ways - boats, noises, etc. - in every part of the wetlands.

As damage by Great Cormorants to fish production is most likely to be realistic on Sardinia (the stomach analyses carried out so far confirmed an almost exclusive Liza diet) and other forms of prevention are hardly conceivable in large natural waterbodies, a similar operation, preferably more reduced in time and better controlled by conservationists, seems to be the only possible strategy available to Sardinian administrators for the next season.

Nicola Baccetti, Istituto Nazionale per la Fauna Selvatica, Via Ca' Fornacetta 9, 40064 Ozzano Emilia (Bologna), Italy