Moving northward: comparison of the foraging effort of Magellanic penguins from three colonies of northern Patagonia

Abstract

The Magellanic penguin Spheniscus magellanicus has recently colonized two new coastal sites (Islote Lobos and El Pedral), increasing the number of colonies in northern Patagonia, Argentina. Assuming foraging parameters during the breeding season to be valid short-term indicators of population health, we studied several foraging parameters of penguins from the two new established sites and from an older and well-established colony (Punta Norte) also localized in the north of Patagonia. Penguins from the recently formed colonies performed shorter foraging trips and visited waters closer to their colony than birds from Punta Norte, with penguins from Punta Norte spending almost twice the time at sea spent by penguins from El Pedral. Penguins from Punta Norte also spent more time underwater, spent a higher proportion of the complete diving cycle searching for prey, performed more wiggles (indicative of prey capture) and had fewer estimated prey captures per unit time underwater than penguins from Islote Lobos and El Pedral. This information suggests that, given no limitations on nest-site availability and no prevalence of predators, the good foraging conditions around El Pedral and Islote Lobos may be implicated in the increase in these two relatively new colonies.