Royal Netherlands Institute for Sea Research
Royal Netherlands
Institute for Sea Research

Seabird diets and population dynamics

The North Sea is extensively used for its fish supply and offshore energy sources. At the same time, the North Sea has significant ecological values. How sensitive are seabirds to changes in food supplies and their foraging habitat? At NIOZ we study diet and demography of Herring Gulls (Larus argentatus) and Lesser Black-backed Gulls (Larus fuscus). Within these generalist gulls, individuals are more or less specialised in what they eat: individuals can forage in marine habitats, in rural or in urban habitats. One of the main aims of this project is to unravel how these specialised individuals adapt to changes in North Sea habitat suitability due to windfarm construction, and changes in food supplies due to changes in fish stocks and the ban on discards. 

During the breeding period between April and August we collect data on reproduction and offspring growth rates in the breeding colony at Texel, and collect information on individual diets. We catch and colour ring gulls, and work with GPS tagged birds as well. We sort out diet samples in the lab and analyse food remains to the level of individual prey items, and analyse feather and blood samples of individual gulls for stable isotope signatures.

Within the scope of ongoing research, various research questions can be thought of. Examples are: ‘Are diets repeatable within-year and between-year?’ ‘Do chick diets overlap with that of their parents?’ ‘Does growth and survival depend on diet?’ Depending on the period, the project can involve fieldwork and lab work. We will discuss particular interests with the students at the start of the project.


We are looking for a motivated bachelor or master student who has great affinity with field- or lab work and data analysis. You must be prepared to work in some weekends as well if fieldwork is included in your project. Projects including fieldwork should start in April and preferably last at least six months. Other projects can start in Autumn or Winter and can be shorter. To know whether or not the project will be a good fit for the student, we would like to meet the student in person at NIOZ before the starting date.

More information & contact

For more information on the project, see: If you are interested in this project, please contact Dr. Rosemarie Kentie ( and Dr. Kees Camphuysen (