Nesting seabirds in SE Spain : distribution , numbers and trends in the province of Almería *

Knowledge on distribution, numbers and trends of seabirds colonies around the Mediterranean Sea still has to be improved. This is the case of the Almería coast in south-east Spain, where there is only partial information regarding number and trends of seabird nesting pairs (e.g., Aguilar et al., 1993; de Juana, 1984; Paracuellos and Nevado, 1995; Paterson, 1997; Tasker and Reid, 1997; Tucker and Evans, 1997). This work reports on seabird numbers and trends SCI. MAR., 67 (Suppl. 2): 125-128 SCIENTIA MARINA 2003

The saltpans of Guardias Viejas was a shallow, saline and seasonal wetland of 150 ha, which disappeared during the period 1994-1998 because of urban development in the area.The lagoons of Punta Entinas-Sabinar (200 ha) are also shallow, salty and seasonal waterbodies.Cañada de las Norias (200 ha) is a deep, brackish and permanent water pool complex that, owing to the extraction of clay and mud for commercial purposes, presents multiple beaches and islets suitable for the breeding of waterbirds.The saltpans of Cerrillos (450 ha) is an abandoned saltpan complex of shallow, salty and seasonal waters.The saltpans of Cabo de Gata (340 ha), still with industrial activity today, have salty, shallow and permanent waters throughout the year.The Cañarete is a rocky coast some 10 km long in the mountains of Gádor, near Almería city, with vertical cliffs on all its shores.The marine cliffs of Cabo de Gata, La Higuera and Cabrera (i.e. from the lighthouse of Cabo de Gata to Carboneras) form another extensive (50 km) and abrupt coast mainly dominated by steep marine slopes, among which beaches of different width are interspersed.San Andrés Island is a rocky islet situated opposite the locality of Carboneras (0.4 km off the coast), of low relief, small size (1.2 ha) and little plant coverage.The islands of Terreros and Negra, very close to each other (1.3 km) and to the littoral cliffs of the mainland (0.7 and 0.1 km respectively), are two rocky promontories with small surface areas (1 and 0.6 ha respectively) and little vegetation cover.Finally, Alborán Island is the largest (7.1 ha) and also the least close to the coast (100 km from the Iberian coast and 50 km from the Maghreb coast).It is delimited by low cliffs and shows a flat profile with sparse bushy vegetation.Some of these sites are legally protected and the others are in the process of protection (Guirado et al., 1997).

METHODS
Data collection started in 1992 but only from 1996 to 2000 a periodical monitoring of the study sites was performed.We censused annually adult seabirds and/or nests during the breeding season (Tellería, 1986).Population trends were obtained for all species except for Cory's shearwater Calonectris diomedea, the European storm-petrel Hydrobates pelagicus and the shag Phalacrocorax aristotelis, owing to the paucity of information.
The Spearman rank correlation coefficient was used when appropriate (Siegel and Castellan, 1988).

RESULTS
Eight seabird species were detected as breeders in Almería during the period 1992-2000 (Table 1).Of these, the most abundant was always the yellow-legged gull Larus cachinnans, with an average of 1,000 pairs, approximately 71% of the total number of seabird breeding pairs per year.Audouin's gull Larus audouinii represented ca.13% of the total and little tern Sterna albifrons 7%.The black-headed gull Larus ridibundus, the common tern Sterna hirundo, Cory's shearwater, the shag and the European storm-petrel represented the remaining 9% (Fig. 2).
We have shown in Table 1 the number of seabird breeding pairs during the breeding season of 2000.The sites with the largest number of pairs during 2000 were Alborán Island and the sea cliffs of Cabo de Gata, La Higuera and Cabrera (i.e.accounting for 50% of the total population).

DISCUSSION
Despite the environmental degradation along the coast of the Almería province during the 20 th century, some seabird colonies of relative importance existed in this region (Paracuellos and Nevado, 1995;Paracuellos and Jerez, 2003).However, the most common species were those favoured by human activities, like the black-headed gull and yel-  low-legged gull (Aguilar et al., 1993).The low degree of human presence at several study sites has also influenced their population increases.
The healthy conservation status of common and little terns was probably linked to the existence of ca.1,000 ha of well-preserved salty wetlands in the province.The common tern was very scarce locally before the 1990s, when it colonised the zone (Aguirre et al., 1995-96).Colonisation of this species was probably caused by an increase in the population on a regional scale (e.g.Díaz et al., 1996) and also by the absence of human disturbance at nesting sites.
Colonies of Cory's shearwater, the European storm-petrel, Audouin's gull and the shag in Almería were the only or some of few known breeding sites for these species in the whole Andalusian territory and in the Spanish Mediterranean, hence deserving full protection (e.g.Aguilar et al., 1993;Paterson, 1997;Ruiz and Rodríguez, 2001).
FIG. 1. -Geographical location of the study sites.Solid circles = wetlands: GV, the saltpans of Guardias Viejas; ES, the lagoons of Punta Entinas-Sabinar; NO, Cañada de las Norias; CE, the saltpans of Cerrillos; CG, the saltpans of Cabo de Gata.Open circles = marine sites: CT, The Cañarete; SG, the cliffs of Cabo de Gata, La Higuera and Cabrera; IS, San Andrés Island; TN, the surroundings of the islands of Terreros and Negra; IA, Alborán Island.

TABLE 1 .
-Number of seabird breeding pairs and number of species at the study sites along the coast of Almería (southern Spain) in 2000.For abbreviations of the study site names see Fig. 1.
FIG.2.-Changes in breeding seabird population numbers in the province of Almería (southern Spain).Data only for those species with ample information available for the period 1992-2000.