Heather Callahan ’21


Ecology and Evolutionary Biology

Project Title

Impact of Grazing Regimes on Rangeland Quality and Wildlife and Livestock Use

Presentation Link

View Heather's Presentation

Certificate(s): Environmental Studies, Language and Culture

I spent the summer in Laikipia County, Kenya, assisting in a study focused on livestock grazing practices. Raising and selling cattle is a major source of income for many Kenyans. During the biannual transition from the dry to the wet season, the animals often become ill and lose weight as their stomach microbiomes adjust to more nutritious food. This leads to profit loss for ranchers trying to sell these animals. Our team tested a silage treatment to prevent this period of transitional weight loss. Each week, I helped weigh the cows, create time budgets describing their behavior, and set up GPS trackers to determine how far different herds foraged for food. I also assisted with analysis of all data collected. Through this position, I learned how to conduct original research, which will be extremely valuable to me as I begin my senior independent work.


Internship Year


Project Category

Biodiversity and Conservation


Rubenstein Group, Mpala Research Centre, Nanyuki, Kenya


Daniel Rubenstein, Class of 1877 Professor of Zoology, Professor of Ecology and Evolutionary Biology, Princeton University