Eggs and Hatchlings of the Magpie Goose Anseranas semipalmata

Abstract

The Magpie Goose produces unusually large clutches of eggs (mean = 9.8) slightly smaller in size (mean = 104.2 g) than predicted from allometric equations relating egg size to female body weight in waterfowl. Incubation temperature (37.1°C) is similar to that achieving optimum hatching rates in the Anatidae. The incubation period of 28 days is within the range reported for other waterfowl, including anserine geese. Rate of evaporative water loss from eggs under natural conditions may be low compared with many birds, including other waterfowl. Hatchlings from artificially incubated eggs weighed 74.6 g, 68.6% of estimated fresh weight of eggs from which they hatched: weight of enclosed yolk averaged 11.3% of hatchling weight. Hatchling weight, head, wing and leg measurements were significantly positively correlated with egg size. Within clutches, the last eggs to hatch were lighter and produced smaller hatchlings. Hatchling dimensions did not differ significantly between sexes.