Salmonella Carriage By Herring Gulls in the Clyde Area of Scotland in Relation to Their Feeding Ecology

• Published in: The Journal of applied ecology 1985-12, Vol.22 (3), p.669-679
• Main Authors: Monaghan, P., Shedden, C. B., Ensor, K., Fricker, C. R., Girdwood, R. W. A.
• Format: Article
• Language: English
• Subjects: Age structure; Aviculture; Bacteriology; Biological and medical sciences; Bird nesting; Bird pests; Breeding; Breeding seasons; Epidemiology; Fundamental and applied biological sciences. Psychology; Herring; Infections; Larus argentatus; Marine; Microbiology; Salmonella; Salmonella typhimurium; Salmonella virchow; Sea birds
• ISSN: 0021-8901; 1365-2664
• DOI: 10.2307/2403220

(1) Between February 1982 and February 1984, 2985 herring gulls, captured at refuse tips in the Clyde area, were examined for the presence of salmonellae in their faeces; 9.2% of those examined in the breeding season were found to be carrying salmonellae, and 9.8% during the non-breeding season. The most common serotypes isolated were Salmonella virchow and S. typhimurium. (2) The proportion of these herring gulls carrying salmonellae was significantly positively correlated with the incidence of salmonellosis in the human population in the same area at the same time, and presumably reflects the level of environmental contamination. (3) There were no statistically significant differences in carriage rates between different age classes of herring gull, but during the non-breeding season, there was a highly significant difference between the sexes. The rate of female carriage at this time was more than double that of males, and appears to reflect differences in their feeding ecology. (4) A further 163 herring gulls obtained from breeding colonies were similarly examined. These had a significantly higher carriage rate than those examined at refuse tips at the same time, indicating that other kinds of feeding areas may give rise to more frequent infection of gulls. (5) There was no evidence that infection with salmonellae affected the health of the gulls concerned. Such pathogen carriage by gulls, when coupled with their considerable powers of dispersal, may give rise to potential public health problems, particularly when gulls are roosting on potable water supplies.