Meeting Abstract
Time-activity budgets of Eared Grebes (Podiceps nigricollis) have been measured at least four times at fall staging areas on two continents. We created a time-activity budget based on focal animal sampling on a post-wintering lake, Salton Sea, California and converted it to an energy budget based on respirometry studies done earlier on captive grebes. Our study covered five periods from late February to late April, 2014. We found that the amount of time devoted to specific activities changed with observational period, but that the grebes’ daily energy expenditure (DEE) varied very little from a mean of 542 kJ/d and even less from a mean 2.4 x BMR. When we compared our study with those of fall staging grebes from other studies, we again found large variations in how the birds used their day, but consistency in DEE and again a 2.4 multiple of BMR. We believe the BMR multiple we are seeing in our non-breeding sedentary grebes represents the sustained metabolic scope (SusMS) predicted by Peterson et al. (1990) but never reported before as a recurring value in different situations.
