Student Projects - Biology

Project Name

Sex Ratio and Stress Response in Magellanic Penguin Chicks at a Colony Newly Exposed to Tourist Visitation

Project Description

In this experiment, sex-disparity at hatching was investigated in a semi-altricial seabird, the Magellanic Penguin (S. magellanicus). At the San Lorenzo Colony on the Peninsula Valdez, Chubut, Argentina, there are substantially more adult males than females. We wished to determine whether this skewed sex ratio is present at hatching or a product of differential post-hatch survival. Additionally, we wished to determine whether anthropogenic disturbance, in this case, the presence of a frequently used tourist trail, had an effect on the sex ratio at hatching of chicks due to the physiological differences of adults along the trail.

In this experiment, blood samples were taken from pairs of chicks and subsequently had PCR run on them using P2/P8 primers. These primers amplify intronically unique sections on avian Z and W sex chromosomes that combined with gel electrophoresis allows for accurate sex determination because of unique male/female banding patterns.

Project Outcomes

The results indicate that sex ratio is not different from the expected 50/50 correlation in either the tourist or non-tourist areas. These data do support the notion of differential post-hatching survival as a cause for a male-biased adult population. The morphometric data from male/female nests suggests that males are out-competing females pre-fledge.

This project is one component of a larger paper on stress physiology of the Magellanic Penguin and a manuscript for publication is now in preparation.