Resource utilisation in herring and lesser black-backed gulls

From RuediPopulation numbers of herring and lesser black-backed gulls have been decreasing over the last 40 years. Reasons for these declines are not fully understood, however, such decreases suggest substantial environmental change. One such cause may therefore be changes in resource availability. This project will characterise the foraging niche of the gulls to study spatial and temporal changes in gull resource use. It will test associations between diet and population changes and characterise the gull species as being made up of either individual generalists or individual resource specialists.  

Data on diet will be collected via stable isotope analysis of gull feathers. Feather keratin is metabolically inert so preserves the isotope ratios of the diet from the time it was synthesised. This allows the use of feathers from museum and contemporary specimens representing over 150 years of diet changes from across the UK. Carbon isotopes will indicate a marine or terrestrial diet source and nitrogen the trophic level of feeding. Diet data will then be analysed along with population data from the main UK seabird censuses.

By examining resource utilisation, this study will attempt to characterise one of the underlying mechanisms determining abundance in these species. This is critical for understanding population dynamics in these two gull species currently experiencing decline.‌

Researchers

Laura Gordon

Nina O’Hanlon

Ruedi Nager

Funding

This is Laura’s MRes Independent Research Project