The conservation status and population decline of the African penguin deconstructed in space and time

• Published in: Ecology and evolution 2020-08, Vol.10 (15), p.8506-8516
• Main Authors: Sherley, Richard B., Crawford, Robert J. M., Blocq, Andrew D., Dyer, Bruce M., Geldenhuys, Deon, Hagen, Christina, Kemper, Jessica, Makhado, Azwianewi B., Pichegru, Lorien, Tom, Desmond, Upfold, Leshia, Visagie, Johan, Waller, Lauren J., Winker, Henning
• Format: Article
• Language: English
• Subjects: Abundance; Bayesian analysis; Bayesian state‐space model; Benguela ecosystem; Colonies; Conservation; Conservation status; Eggs; extinction risk; Fisheries; Growth models; Growth rate; IUCN Red List assessment; Mathematical models; Original Research; Population; Population decline; population dynamics; Population growth; Prey; seabird conservation; Threatened species
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6554

Understanding changes in abundance is crucial for conservation, but population growth rates often vary over space and time. We use 40 years of count data (1979–2019) and Bayesian state‐space models to assess the African penguin Spheniscus demersus population under IUCN Red List Criterion A. We deconstruct the overall decline in time and space to identify where urgent conservation action is needed. The global African penguin population met the threshold for Endangered with a high probability (97%), having declined by almost 65% since 1989. An historical low of ~17,700 pairs bred in 2019. Annual changes were faster in the South African population (−4.2%, highest posterior density interval, HPDI: −7.8 to −0.6%) than the Namibian one (−0.3%, HPDI: −3.3 to +2.6%), and since 1999 were almost −10% at South African colonies north of Cape Town. Over the 40‐year period, the Eastern Cape colonies went from holding ~25% of the total penguin population to ~40% as numbers decreased more rapidly elsewhere. These changes coincided with an altered abundance and availability of the main prey of African penguins. Our results underline the dynamic nature of population declines in space as well as time and highlight which penguin colonies require urgent conservation attention. Understanding changes in abundance over space and time is crucial for conservation. We use 40 years of count data and Bayesian state‐space models to deconstruct the decline of the African penguin population (almost 65% since 1989) in time and space. Our results underline the dynamic nature of population declines and highlight areas in need of urgent conservation attention, such as the South African colonies north of Cape Town that have declined at nearly 10% per annum since 1999.