Changes in Body Weight of American Goldfinches

Publication Type:Journal Article
Year of Publication:1975
Authors:Wiseman, AJ
Journal:The Wilson Bulletin
Date Published:1975
ISBN Number:00435643
Keywords:Carduelis, Carduelis carduelis, Fringillidae, Spinus, Spinus tristis
Abstract:During a general banding program conducted on weekends for 5 years at the Cincinnati Nature Center, weights and wing chord measurements of American Goldfinches were recorded. From this, 1448 weights of 978 males and 756 weights of 538 females were obtained, treated as separate populations, and divided into agerelated samples representing various time and biological periods. The means ± 2 S.E. were used to make simple comparisons between seasons, weekends, days, and hourly periods. A comparison of weights by months showed weights were inversely related to temperature. Evidence of an increase in weight during molt was noted. During the summer, the lowest (basic) mean weights were attained (12.5 g for males and 12.4 g for females), and both sexes gained about 4% during the day. During the breeding season the females gained 7.3% and males gained 4.9% above the basic mean weight. In February, the male mean weight was 35.6% and the female mean was 34.4% above the basic mean weight. At this time males gained 19% during the day, but in March they gained only 5.5% in a day. Fat classes (deposits) were shown to change paralleling the hourly changes in mean weight. /// The date of capture and mean weights were not correlated. The hour of capture produced significantly lower mean weights in the earlier hours of the colder months, but not in the warmer months. The handling of birds appeared to reduce the gain in diurnal weight during February and March. Variations in mean weights between various years in selected months were found to be related to hour of capture or weather in some cases. The effects of weather were demonstrated. Changes in solar radiation, wind direction and velocity, and immediate changes in temperature seemed to affect weight and feeding activities in hourly and daily periods. The ratio of total weight to wing chord was shown to vary with season, sex, and age. In both sexes, the newly fledged young had significantly longer wing chords than most adults of their sex.
Short Title:The Wilson Bulletin
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