Weights and Primary Growth of Brent Geese Branta bernicla Moulting in the Queen Elizabeth Islands, N.W.T., Canada, 1973-1975

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Abstract
Weights of 900 brent geese captured at 30 sites while flightless are examined. The geese included representatives of 2 breeding stocks and some molt-immigrants. The population to which an individual belonged seemed to have less effect on its weight than did its age, sex, recent breeding effort or the site where it was molting. The mean weights, in kilograms, of adult males were 1.37 .+-. 0.35, of adult females 1.23 .+-. 0.40, of yearling males 1.22 .+-. 0.26, and of yearling females 1.16 .+-. 0.28. Females that had laid tended to weight less than nonbreeders taken in the same place. Though the weather in the spring and summer of 1974 was exceptionally poor, so that no geese nested and there was little plant growth, molting geese weighed as much in late July 1974 as in the other years. The geese at a few sites weighed well above the general average. The mean weights of these molters are only 5-7% less than the annual means of a collection of published weights of other brent geese. Capture caused appreciable temporary loss of weight, averaging 80 g after 5 d [days]. Measurements of the growth of the longest primary feather indicated a mean daily increment of about 6 mm d-1; the geese being able to fly again before the wings are fully grown, the flightless period was no more than 22-25 d. Individuals with well grown new primaries weighed less than those caught at the same time and not yet showing new primaries, the difference being more marked in males.

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