Seabird Group Seabird Group

First recorded breeding attempt of Redfooted Booby Sula sula on St Helena Island, South Atlantic

Annalea Beard1* ORCID logo and Philip Lambdon2

https://doi.org/10.61350/sbj.29.15

1 Marine Section, Environmental Management Division, St Helena Government, Essex House, Jamestown, St Helena Island, South Atlantic;

2 St Helena Nature Conservation Group, PO BOX 32, Jamestown, St Helena Island, South Atlantic.

Full paper

Abstract

Red-footed Boobies Sula sula are a wide ranging species that used to have a significant breeding population on both Ascension and St Helena Island in the South Atlantic. It was thought that only a small remnant population existed at Ascension Island until now. Five breeding attempts on the southern coastal windward side of St Helena by white morph Red-footed Boobies were recorded using an infra-red motion sensitive camera during 2014–2015. Of the minimum of nine eggs laid, none hatched suggesting more than one female was involved in nesting efforts and they were infertile and/or inexperienced breeders. Theories as to where these birds may have come from are discussed.

Introduction

Red-footed Boobies Sula sula have a wide range, occurring on tropical islands in most oceans (del Hoyo et al. 1992) where they nest predominantly in trees and shrubs. The sub-species, S. s. sula is restricted to the Atlantic, predominantly the Caribbean with outposts around the Brazilian Islands of Trinidade and Fernando de Noronha (Harrison 1985), and further east on Ascension Island. The South Atlantic population is approximately 4,000 individuals (den Hartog 1987) and holds both white and white-tailed brown morphs, although the relative proportions of each morph are not known (Nelson 1978). The small, remote islands of Ascension and St Helena, which lie in the South Atlantic Ocean close to the mid-Atlantic Ridge, once harboured significant breeding populations (Ashmole 1963a,b). The introduction of predators following discovery of the islands in the 16th century, and subsequent deforestation of St Helena after human colonisation, reduced the Red-footed Booby populations to a tiny remnant on Boatswain Bird Island, an offshore islet off the southwest coast of Ascension Island (Stonehouse 1962; Simmons 1990). Here we report recent breeding attempts of this species, previously thought to be absent on mainland St Helena, including additional individual observations of non-breeding birds from 2010 to 2015.

Acknowledgements

We thank Graham Sim, Ivan Henry, Emma Fowler, Edward Thorpe, Sophy Thorpe and Remi Bruneton for additional observations; St Helena Government for help producing the map and Richard Sherley for advice and comments on the manuscript.

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