Ardea
Official journal of the Netherlands Ornithologists' Union

login


[close window] [previous abstract] [next abstract]

Ebbinge B.S. (1985) Factors determining the population size of arctic-breeding geese, wintering in Western Europe. ARDEA 73 (2): 121-128
The changes in size of three well-monitored arctic-breeding goose populations that winter in Western Europe (including the British Isles) are reviewed. It is apparent that all three populations, viz. the Icelandic-British population of the Pink-footed Goose, the Baltic-North Sea population of the White-fronted Goose and the world population of the Dark-bellied Brent, have increased in number, but the timing of the increase differs. Recent ringing results show that exchange between populations that until now were considered to be completely isolated from one another does occur. However, this exchange takes place on such a small scale that it cannot account for the observed increase. Data on the numbers and the proportion of first-year birds indicate that a marked decrease in mortality is the primary cause for this increase. In two cases a dramatic increase in population size started immediately after a major restriction on hunting came into force. It is concluded that mortality due to hunting is largely supplementary, and not compensatory. Possibly the natural mortality rate is at present quite low because exploitation by man has kept the population levels of geese wintering in Europe at a level well below the capacity of their arctic breeding grounds. Now that a considerable increase has taken place, density- dependent regulation of the reproduction is noticeable in two of the reviewed populations: a decreasing proportion of the potential breeders breeds successfully, and in the case of the Icelandic Pink-feet brood size of the successful breeders also has decreased as the population size has increased.


[close window] [previous abstract] [next abstract]