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A summer studying swallows

By Anna Stevens '10
August 4, 2008

A large colony of cliff swallows tucked beneath a bridge in Cannon Falls, Minn., served as the perfect subject for a bird lover's research project this summer. This common bird provided a summer that was anything but ordinary for St. Olaf student Allison Johnson '10, who found herself climbing a ladder over the Cannon River to research how parent swallows recognize their young in the nest.

As part of her research, Allison Johnson '10 took many photos, including these, of the facial patterns of fledgling swallows.
"The research is not what I would expect it to be," Johnson says. "It is amazingly time consuming, but really rewarding when it works."

A biology major, Johnson's interest in evolution merged with her interest in birds to form the idea for this project. Her research studies the facial patterns on fledgling swallows to determine whether parents use the patterns as an indicator of which babies in their nest are their own offspring.

Swallows typically experience egg swapping in the nests and have multiple mates, Johnson explains. Female swallows commonly move their eggs from one nest to another or lay their eggs in another swallow's nest. This creates nests of baby swallows that are not necessarily related to the parent left to raise them. During times of limited food supply, it is possible that swallows use some type of indicator to determine which babies are their own, and then only feed their recognized offspring, Johnson says.

With the help of St. Olaf Professor of Biology Steve Freedberg, Johnson and an assortment of other students and faculty sampled more than 600 birds this summer. The preliminary testing being performed in the project's first year includes multiple stations. The bird's blood is drawn to be DNA tested in order to determine family ties. The facial patterns are then photographed to focus on their differing patterns. Finally, the swallows are weighed with the goal of finding a correlation between the amount they are fed and their genetic link to the adult swallow in their nest. After all of the findings are collected, they will be shared with Professor of Statistics Paul Roback, who will analyze the results with statistics students.

Cliff swallows build conical mud nests and live in large colonies such as this one that Johnson studied and photographed.
Freedberg and Johnson hope to receive a grant to continue and elaborate on the research in future years. As they continue to study the facial patterns, they also plan to study the egg-laying tendencies of swallows, possibly using video to capture the egg swapping on film. The pair also would like to present their initial findings at a scientific conference, as well as author and publish a scientific paper.

Johnson plans to continue following her interest in birds and evolution, and she is considering studying evolutionary biology in graduate school.

Contact Kari VanDerVeen at 507-786-3970 or