Population distribution shifts of Magellanic Penguins in northern Patagonia, Argentina: Implications for conservation and management strategies

Abstract

Wildlife populations are dynamic and changes in their spatial distribution and/or abundance at different locations may potentially change the scenarios under which conservation efforts should be allocated. To maximize success in management and/or conservation actions, regular monitoring and dynamic frameworks to re-adapt strategies are needed. Fluctuations in the size of penguin populations and shifts in the distribution pattern may reflect the combination of natural and anthropogenic alterations in their marine and coastal habitats where they forage and breed, respectively. This study updates information on the breeding distribution of Magellanic penguin (Spheniscus magellanicus) and their abundance along 1,200 km of coastline along its northernmost Atlantic breeding range, allowing to assess population trends at the colony level and to compare the status of the overall population at the regional scale. A total population of 643,070 pairs was estimated at 30 colonies, most of which were located on islands (70%). Colony size was highly variable, from 3 to 204,416 breeding pairs. Results show a clear northward redistribution with new recent settlements expanding the breeding range by 1° latitude. The overall breeding population in this coastal sector increased by about 19.7% (CI 10.7%–29.72%) from the mid-1990s to the 2015–2017 period. Growth rates varied among coastal sectors, but most colonies in the northernmost area (Rio Negro and northern Chubut) had consistently high rates of increase, while colonies in central and southern Chubut declined or remained relatively stable. Our results reflect the status of Magellanic penguins for over half of their global population and show considerable changes in their breeding distribution in a relatively short time. This dynamic scenario generates new conservation challenges, highlighting the importance of long-term monitoring and the need for coordination between resource managers of the different jurisdictions where Magellanic penguins breed.