Emu Emu Society
Journal of BirdLife Australia
RESEARCH ARTICLE

Female-biased mortality of Magellanic Penguins (Spheniscus magellanicus) on the wintering grounds

Ralph Eric Thijl Vanstreels A E , Andréa Corrado Adornes B , Paula Lima Canabarro B , Valeria Ruoppolo A C , Marcos Amaku D , Rodolfo Pinho da Silva-Filho B and José Luiz Catão-Dias A
+ Author Affiliations
- Author Affiliations

A Laboratório de Patologia Comparada de Animais Selvagens, Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Avenida Professor Orlando Marques de Paiva 87, 05088-000 São Paulo – SP, Brazil.

B Centro de Recuperação de Animais Marinhos, Museu Oceanográfico Professor Eliézer de Carvalho Rios, Universidade Federal do Rio Grande, Rua Capitão Heitor Perdigão 10, 92200-580 Rio Grande – RS, Brazil.

C Emergency Relief Team, International Fund for Animal Welfare, 290 Summer Street, Yarmouth Port, MA 02675, USA.

D Laboratório de Epidemiologia e Bioestatística, Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Avenida Professor Orlando Marques de Paiva 87, 05088-000 São Paulo – SP, Brazil.

E Corresponding author. Email: ralph_vanstreels@yahoo.com.br

Emu 113(2) 128-134 https://doi.org/10.1071/MU12060
Submitted: 29 July 2012  Accepted: 20 December 2012   Published: 1 May 2013

Abstract

Magellanic Penguins (Spheniscus magellanicus) migrate thousands of kilometres from their breeding colonies every winter. Despite the significance of this seasonal movement, aspects of its ecology and implications for conservation biology remain enigmatic. We examined the sex of 528 Magellanic Penguins either beachcast (found dead ashore) or stranded (found alive ashore) in wintering grounds of southern Brazil from 2002 to 2009. We found evidence that: (a) among beachcast Penguins, females significantly outnumbered males; (b) for stranded Penguins that had not been oiled, the sex-ratio was significantly female-biased, whereas among oiled Penguins the sex-ratio was even; (c) among stranded Penguins, females had a lower rate of survival through rehabilitation than males; and (d) for both sexes, juvenile Penguins surviving rehabilitation had greater body mass upon admission than those that died. Our findings suggest an increased mortality of juvenile and adult females might occur during migration, and emphasise that sex may play a significant role in the movement ecology and conservation of this species. Conservation efforts might thus benefit from incorporating sex-based strategies to ensure that biased sex mortality does not have a negative effect on the species, and researchers are encouraged to consider sex as a key component in the ecological research and conservation efforts of this, and other, species of penguin.

Additional keywords: seabird, South American birds, ecology, survival, sexual dimorphism.


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