Population Dynamics of Magellanic Penguins in North and Central Patagonia: A Metapopulation Approach

POZZI, LUCIANA; GARCÍA BORBOROGLU, PABLO; BOERSMA, DEE; PASCUAL, MIGUEL

Victoria

Congreso; 1st World Seabird Congress; 2010

Birdlife International

Magellanic penguins (Spheniscus magellanicus) have 63 breeding colonies distributed along 4000 km of coastline in Patagonia, Argentina, with a minimum population of 950,000 breeding pairs. No demographic studies have been conducted to evaluate trends under a regional perspective. We estimated population size and breeding success at large colonies scattered along Northern and Central Patagonia and assessed trends using population growth models. To evaluate dispersion we searched five colonies for penguins hatched and banded between 1983 and 2009 at Punta Tombo. In the North, colonies increased steadily after theiy were first establishment in the late 1960’s. Río Negro, the northernmost Atlantic breeding location, increased from 22 breeding pairs in 2002 to 3,751 in 2009 ( = 2.21) In Peninsula Valdes, large colonies increased: San Lorenzo incremented from 93 breeding pairs in 1977 to 100,000 in 2008 ( = 1.22). In Central Patagonia, the biggest colonies declined, including the largest colony in the world, Punta Tombo. Isla Leones decreased from 96,287 pairs in 1995 to 47492 in 2009 ( = 0.95). Islas Vernacci, an order of magnitude smaller grew from 21,868 pairs in 1993 to 27,736 in 2008 ( = 1.02). Breeding success was higher in northern colonies. Out of 82,695 birds checked for bands, the three banded penguins found breeding in the Peninsula Valdes hatched at Punta Tombo in 1988 and .. Closed-population scenarios may not explain trends for particular locations hence dispersal might be an important driver on colonies that are expanding at the northern part of the Magellanic penguin’s breeding range and in the decline of penguins in the central part of their range.