Investigating beak size variation in Passer sparrows (internship/thesis)

Bird beaks are highly multifunctional structures, used for foraging, temperature regulation, singing and preening. The varied and sometimes competing selective pressures imposed on the bill have led to huge among- and within-species diversity in beak size and shape. This variation has long fascinated evolutionary biologists, with Darwin himself famously noting the link between dietary preference and the range of bill shapes found among finches in the Galapagos.

The house sparrow (Passer domesticus domesticus) is a globally distributed human commensal, that is, a species which depends upon human resources for survival. House sparrows likely began to associate closely with humans during the Neolithic, when human societies started developing agricultural practices. During this time, the house sparrow likely underwent a dietary shift, exploiting the increased abundance of tough cultivated cereal grains made available. To accommodate this dietary shift, the house sparrow may have undergone dietary associated phenotypic adaptation, including changes in bite force as well as beak size and shape.

This project will combine a comparison of existing bill images taken from house sparrows and a non-commensal subspecies (the Bactrianus sparrow) with collection of new data from a captive house sparrow population to investigate the association between beak morphological variation and human commensalism. The student will answer two main questions:

• Does beak size differ between geographically distinct house sparrow populations?
• Does beak size differ between human commensal and non-commensal Passer sparrows?

The project is suitable for a Master’s student thesis or internship or a BSc/HBO student internship. During the project, the student will develop skills in data and image analysis, written and verbal presentation skills and bird handling.

Requirements for the role:

Candidates should be enthusiastic about ecological and evolutionary research. The working language of the group is English, so a good level of written and spoken English is essential whilst Dutch language proficiency is not required