Magellanic Penguins (Spheniscus Magellanicus ) Population Dynamics in Patagonia, Argentina.

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

Hobart, Tasmania, Australia

Congreso; International Penguin Conference; 2007

University of Tasmania

There are 63 breeding colonies of Magellanic penguin (Spheniscus magellanicus ) along the Patagonian coast of Argentina. The total minimum population size is 950 000 breeding pairs. Historical information suggest that penguins colonization proceeded in a northward direction in the last century. Current population trends are mixed. In Chubut province, some colonies are declining, including the largest Magellanic penguin colony in the world, Punta Tombo (44° 02´S 65° 11´W), while the northern most colonies at Península Valdés are increasing. Spatially structured populations can be divided in population units. The balance between its internal and external processes produces changes in its populations and differentiates the population types described: sources, sinks and pseudosinks. Punta Tombo was first colonized in the early 1920s and initially would have been a sink, attracting individuals from southern colonies. It probably turned into a pseudo-sink, becoming the largest Magellanic penguin colony in the world. This colony may have been a source for the colonies in the Península Valdés where breeding penguins were first seen in 1969. Population models, however, indicate that the actual numbers found at Península Valdés colonies should be much lower than they are. We suggest that the northern colonies are still dependant on the southern colonies for their rapid growth.