Absence of daily rhythms of prolactin and corticosterone in Adelie penguins under continuous daylight

Plasma prolactin and corticosterone levels were measured in free-living Ad6lie Penguins (Pygoscelis adeliae) at TorgersenI sland, Antarctica (64?S latitude), at 4-hr intervals throughout the day during early January 1997 and examined for evidence of a 24-hr rhythm. At this season and latitude, natural daylight is continuous. No significant change in the plasma level of either […]