Date of Award
MS Marine Science
Environmental and Ocean Sciences
Hugh I. Ellis, Ph.D.
Ellen Freund, Ph.D.
Thomas W. Anderson, M.Sc.
Time-activity budgets have been a widely accepted way of approximating the daily energy expenditure of many species, including waterbirds. For this study, focal animal sampling was used to study Eared Grebes (Podiceps nigricollis) at their post-wintering stopover site, Salton Sea. Daylight time-activity budgets were converted to energy budgets using energy equivalents for diving, preening, swimming, and resting on water developed for Eared Grebes previously by H. I. Ellis (1994). Post-wintering Eared Grebes arrive at Salton Sea in waves at differing times in the spring. As a result, there can be individuals in a variety of physiological states during the same time period. For example, some grebes may be actively feeding and putting on fat at the same time others are no longer feeding and are preparing to migrate. Dive bout behavior was highest when the majority of the grebe population was still arriving, and decreased throughout the period of time that the population was present. As grebes dived less, they spent more time in non-diving activities, except for the maintenance behavior of preening, which did not change among the five observational periods. The grebes expended a similar amount of energy throughout each observational period even though they have different patterns of behaviors. Assuming that grebes spend most of their time at night resting, the 24-hour daily energy budget ranged from 2.36 - 2.49 x BMR.
Digital USD Citation
San Francisco, Samantha, "Time-activity and energy budgets of Eared Grebes (Podiceps nigricollis) at Salton Sea" (2017). Theses. 20.
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