Breeding and foraging ecology of cavity nesting seabirds at St Helena, South Atlantic

Beard, Annalea 2024. Breeding and foraging ecology of cavity nesting seabirds at St Helena, South Atlantic. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis examines the breeding and foraging ecology of two cavity nesting seabirds in the South Atlantic: Band-rumped Storm-petrels (Hydrobates castro) and Red-billed Tropicbirds (Phaethon aethereus). Chapter 1 provides a general introduction to the thesis. Chapter 2 characterises a range of aspects of Red-billed Tropicbird breeding ecology, against which the effectiveness of future monitoring and conservation measures can be gauged. St Helena's population represents the largest colony in the South Atlantic and an internationally important part of the global population, but has the lowest breeding success (33%) reported globally. Chapter 3 describes the successful use of artificial nest chambers as an effective conservation tool to aid monitoring and management of cavity nesting seabird species using the Band-rumped Storm-petrel at St Helena as a case study. Chapter 4 examines factors influencing body condition regulation in Red-billed Tropicbirds and its impact on their breeding regime at St Helena, including detailed chick growth rates from two localities in the Atlantic Ocean. Significant differences in incubation behaviour and body condition between years were identified, along with sex-specific incubation routines. GPS tracking of the seasonally segregated population of Band-rumped Storm-petrel breeding at St Helena (Chapter 5) confirmed differentiated foraging behaviour and at-sea distribution between hot and cool season breeders, offering insights into the drivers of sympatric speciation. Red-billed Tropicbird dietary composition and diversity at St Helena (Chapter 6) indicated highly specialised feeding that predominantly relied on juvenile epipelagic squid. Risk of bycatch was deemed low. Implications in relation to existing and potential future commercial and local fisheries practices, within its known foraging range, are discussed. This thesis provides essential knowledge for the formulation of informed and effective conservation and management of the two seabird species in the South Atlantic, requiring urgent conservation actions.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	25 October 2024
Date of Acceptance:	25 October 2024
Last Modified:	25 Oct 2024 16:17
URI:	https://orca.cardiff.ac.uk/id/eprint/173400

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