Update of the Population Status of Magellanic Penguins in Península Valdés, Chubut, Argentina

Abstract

During 1991 and 1993 we surveyed the coasts of Península Valdés , identifying five colonies of Magellanic penguins (Spheniscus magellanicus): Isla de los Pájaros, Estancia San Lorenzo, Caleta Externa, Islas de la Caleta and Caleta Interna. At Isla de los Pájaros there were 47 active nests. The Estancia San Lorenzo colon y, with 17034 ± 2553 active nests in 1993, occupied an area of 73 ha (3 km long by 50 and 450 m wide) and presented a mean nesting density of 2,43 nests/100 m2. During October 1994 we found a small settlement of 483 active nests about 4 km W of this colony. The Caleta Externa colony, with 10973 ± 1807 active nests, extended 5 km long and 100 and 500 m wide. Nesting density was significantly higher in 1993 (0.77 nests/100 m2) than during 1991 (0.50 nests/100 m2). The Islas de la Caleta colony, with 9456 and 13780 active nests in 1991 and 1993, respectively, occupied 21 ha on the SE coast of Isla Primera. During 1993, we found 38 new nests at Isla Segunda and 19 nests in front of Isla Primera, on the W coast of Caleta Valdés. Finally, the Caleta Interna colony, with 1281 and 1553 active nests in 1991 and 1993, respectively, extended in patches along 4,7 km of coastline. The observed increase in the number of nests suggests that the population is recruiting individuals from colonies close to Península Valdés . Even though the population is increasing, the current trend in the use of natural resources in Península Valdés for tourist purposes and the coastal development of nearby areas requires careful design of management guidelines to minimize the impact on Magellanic penguins.