Population Behavior of Eastern Arctic Canada Geese
1966; Wiley; Volume: 30; Issue: 3 Linguagem: Inglês
10.2307/3798746
ISSN1937-2817
Autores Tópico(s)Plant and animal studies
ResumoThe Canada geese (hutchinsii-parvipes complex of Branta canadensis) which nest in arctic Canada east of 1040 W have developed a complex system which enables the population to survive and expand its range under the changing ecological conditions of its present breeding grounds. The popu- lation has an irregular migration pattern, dependent in part on the presence of green vegetation at fa- vored stopover points. Sight records of neckbanded geese indicate that birds from one nesting locality spread throughout the migration range and mix freely with birds from other nesting areas. This popu- lation probably pairs in spring, with the peak of sexual activity occurring during the later stages of northward migration, when geese from many nesting localities are mixed together. Measurements of 17 mated pairs indicate that mating is assortative; the male of the pair was always larger than the fe- male even though large females were available in the population. In samples taken at McConnell River and Southampton Island, Northwest Territories, significant differences were found between the means and variances of morphological characters measured, yet the ranges of observed variation were very similar. Most habitat presently occupied by Canada geese in eastern arctic Canada is of very recent geologic origin, and the climate is undergoing long-term amelioration. Length of the summer season is critical in limiting the survival of geese. Because larger geese probably are less successful than smaller geese in producing young in short summers, but more productive in long seasons, populations living in more severe climate should contain a higher proportion of small geese. It is proposed that the transfer of individuals between local nesting areas, coupled with selective mating and individual variation, are mechanisms which may improve the average survival of Canada geese in a variable and fluctuating en- vironment.
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