Health status indices of Kelp Gull populations in South Africa

ABSTRACT

Kelp Gulls Larus dominicanus are widespread globally due to their ability to exploit a wide variety of resources and foraging habitats inland, in coastal areas and offshore. However, the increasing availability of anthropogenic diet items might potentially impact the health of their populations. We investigated body condition and parasite loads of incubating adult Kelp Gulls and their chicks at seven South African breeding colonies with varying proximity to landfills. Adult body condition indices did not differ significantly among colonies during the incubation period but were on average highest at one of the urban colonies, Strandfontein, which is next to a large landfill site in Cape Town. The only blood parasite identified was Haemoproteus spp. Prevalence overall was low, but significantly higher in adults than in chicks. Yeast cells (Candida spp.) were identified in faecal smears and coincided with higher body condition index values in incubating adults. Our results suggest that urban landscapes currently have little impact on these aspects of gull health, at least on individuals in good enough condition to breed.

KEYWORDS:

• Larus dominicanus
• anthropogenic impact
• body condition index
• blood parasites
• faecal parasites

Acknowledgements

We thank Nicolás Suárez, Ralph Vanstreels, Renata Hurtado, Renee Schoeman, Titus Shaanika, Giannina Passuni, Bianke Fouche, Oluwadunsin Adekola, Manon Amiguet, Carol Mitchell, Mariëtte Wheeler, Gwen Traisnel, and Diane Le Gouvello for their assistance in the field and Pierre Nel for coordinating access to Malgas and Jutten Island. Transport to the islands was made possible with the help of Elite charters and to the Steenbras Dam colony through African Blue Marine. Tim Mayes granted permission to work on the salt pans and Sayed Stoffels to work at Steenbras Dam. Special thanks to Nola Parsons for analysing the parasite samples.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, K Reusch, upon reasonable request.

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/01584197.2022.2114089

Additional information

Funding

This work was supported by the FitzPatrick Institute of African Ornithology Centre of Excellence; and the National Research Foundation.