Fat reserves and condition indices in greater snow geese

Abstract

We evaluate several external condition indices as predictors of total fat reserves (TFR) in greater snow geese. In 1979 and 1980, we collected 373 adult geese during their spring staging halt along the St. Lawrence estuary, Québec, and determined their fat content by ether extraction. Body weight (BW) alone and BW divided by various morphometric measurements are relatively poor predictors of TFR (maximum r2 = 0.56). The thickness of subcutaneous fat (measured externally with an adiposimeter) combined with BW is the best predictor of TFR (R2 = 0.65). This condition index can be useful in predicting the average condition of living geese, provided a reasonable sample size is available. We also examined some internal condition indices. Of these, the dry weight of abdominal fat is the easiest to apply and one of the most reliable (r2 = 0.86).