Spatial scales of foraging in breeding Magellanic Penguins

The greatest human threats to most penguin species occur in their marine environment. Development of effective conservation measures has been difficult because until recently, little was known about the location of birds at sea and how these changed with season and among years. We used satellite telemetry to track Magellanic Penguins (Spheniscus magellanicus) in the South Atlantic for eight years to examine how use of the marine environment changes among years and among three breeding stages: incubation, small chick and large chick. Spatial scales of Magellanic Penguins’ use of the marine environment differ among stages of the breeding season. At Punta Tombo, Argentina, Penguins foraged up to 600 km away from their breeding site during incubation, but stayed within about 150 km during small chick, and 300 km during large chick. These scale differences with breeding stage are consistent among years but the distances and exact locations where birds foraged differed among years. The scale differences reflect seasonal oceanographic processes which determine the availability of the Penguins’ prey. The seasonal fronts that concentrate prey species, especially Anchovy (Engraulis anchoita), near the breeding colony occur during the chick-rearing stages. Because Magellanic Penguins forage over large areas, conservation strategies relying on marine reserves or fixed zoning will likely be inadequate. Instead larger scale approaches that encompass the Penguins’ foraging areas, such as resource management zones, are necessary. A conservation model that considers breeding stage and environmental variation in management of the marine environment may be useful for other long-distance foragers.