Seabird Group Seabird Group

Pseudo-egg “fabrication” by Grey-headed Albatrosses Thalassarche chrysostoma on Marion Island

Stefan Schoombie* and Janine Schoombie

1 FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa

Full paper

Introduction

Pseudo-eggs are foreign objects, resembling eggs, found inside the nests of birds (Conover 1985) and have been recorded in several ground-nesting seabirds (Coulter 1980; Conover 1985; Mellink 2002; DeStefano et al. 2013; Wagner et al. 2013; Witteveen et al. 2015). They are more common among species that have larger clutches or multiple brood patches (Coulter 1980; Wagner et al. 2013) where pseudo-eggs are included to increase their clutch size (Coulter 1980; Conover 1985; Wagner et al. 2013; Witteveen et al. 2015). Albatrosses and petrels however, only lay one egg; rare two-egg clutches result from two females laying in the same nest, with one of them being an inexperienced breeder (Ryan et al. 2007). The occurrence of pseudo-eggs has only been reported for Laysan (Phoebastria immutabilis) and Black-footed Albatrosses (P. nigripes; Bartholomew & Howell 1964; Grant 1982). We did not find any record of albatrosses breeding in the Southern Ocean that exhibited pseudo-eggs.

Acknowledgements

We thank Peter Ryan for useful comments while drafting this manuscript. Logistical and financial support was provided by the South African Department of Environmental Affairs, through the South African National Antarctic Programme (SANAP), the National Research Foundation and the University of Cape Town. We thank two anonymous reviewers whose comments improved a previous draft of this manuscript.

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