Exploring the interspecific competition between two Arctic-breeding migrants: brent and barnacle geese in the Wadden Sea (MSc internship/thesis) Background Each year, in April and May, dark-bellied brent and barnacle geese gather in the Wadden Sea to build up energy reserves for their long migration to the Arctic breeding grounds. Both species have similar annual cycles, and utilize comparable resources and habitats, especially during fuelling. But their populations show contrasting trends with increasing numbers of barnacle and (slightly) decreasing numbers of brent geese. All in all, it is likely that competition between both species plays (or will play) an important role. Because the consequences for individuals as well as for populations can be devastating, assessing and understanding this competition is indispensable; yet it remains unexplored. To address this, two key questions must first be answered: 1) to what extent do brent and barnacle geese exhibit spatiotemporal overlap during fuelling, and 2) which species is more dominant, or the ‘winner’, within mixed flocks? Your goal and tasks Your primary focus will be on addressing the second key question. Specific inquiries might include: what is the time to conflict with an ‘opponent’ of the other species, and does it vary between species or over time? Which species is more likely to initiate an attack or be targeted, and does the likelihood of losing differ between species? To answer these questions, your tasks include (but are not limited to!): 1. Develop a protocol for standardized data collection (~ March 2025) 2. Data collection on Terschelling (April/May): a. Practical planning and logistics b. Film flocks and record characteristics (size, proportion juveniles, etc.) c. Observe geese using focal sampling (in real life and in the films) 3. Analyze the collected data, write a report and present the results (~ June/July) You may also contribute to answering the first question. Optional tasks include annotating bird species in images, assisting in the development or enhancement of an AI algorithm to identify and count geese in images, or manually mapping the large-scale distributions of flocks. Who are you - An independent, assertive, and motivated MSc student - Strong interest and background in wildlife ecology, birds, and ideally waterfowl or geese - Love for accurate (field) work - Driver’s license B is preferred Practical information - Type: Internship/thesis - Duration: ~ 5 months Planning can be discussed, but field work in April and May - Location(s): Wageningen and Terschelling - Contact: Jan Geisler, PhD-candidate AnE (This email address is being protected from spambots. You need JavaScript enabled to view it.