Variations in Age and Sex Ratios of Wintering American Goldfinches Trapped at Baited Stations (Variación en la Razón de Edad y Sexos de Individuos Invernales de Carduelis Tristis)

Publication Type:Journal Article
Year of Publication:1989
Authors:Prescott, DRC, Middleton, ALA, Lamble, DR
Journal:Journal of Field Ornithology
Date Published:1989
ISBN Number:02738570
Keywords:Astragalinus tristis, Carduelis, Carduelis carduelis, Carduelis tristis, Fringillidae, Spinus, Spinus tristis
Abstract:Data from 3145 American Goldfinches (Carduelis tristis) trapped at baited stations in Guelph, Ontario during the winters of 1980-1986 were analyzed to examine the influence of weather and time of day on sex and age ratios of males. An imbalanced sex ratio of 1.55:1 (male: female) and male age ratio of 0.35:1 (adult: immature) was identified. Diurnal variations in sex and age ratios reflected an increase in the number of adult males around mid-day. No consistent relationship between temperature and sex or age ratios was found. However, immature males were less frequently trapped during snowy weather than during more favorable conditions. /// Durante los inviernos del 1980-1986 se atraparon 3145 individuos de Carduelis tristis en Guelph, Ontario. Se encontró una relación de sexos de 1.55:1 (macho: hembra) y de edad de machos 0.35:1 (adulto: inmaduro) inbalanceada. A través del día hubo variaciónes en la razón de sexos y edad, con un incremento en el número de machos a mediodía. No se encontró relación entre las temperaturas y la razón de edad y sexo. Sin embargo, se atraparon machos jóvenes con menos frecuencia durante períodos de nevadas que durante tiempos más favorables.
Short Title:Journal of Field Ornithology
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