Body mass and lipid content of shorebirds overwintering on the south Texas coast

Three species of shorebirds were collected at bimonthly intervals in 1979-1980, from the time of their arrival in early autumn to mid-February, on the south Texas coast. Female Long-billed Dowitchers (Limnodromus scolopaceus) and Western Sandpipers (Calidris mauri) were heavier (P < 0.05) than males, but the reverse was true for American Avocets (Recurvirostra americana). Lipid content, relative to whole body mass, did not differ (P > 0.05) between sexes in any of the three species. During the wintering period, fat stores in Long-billed Dowitchers and Western Sandpipers declined 70% and 44%, respectively, but not in American Avocets. Lipid content was highly correlated (P < 0.001) with body mass in all three species, providing further evidence that fat accumulation is responsible for the major variation in total mass of some shorebird species.