Publication Type: | Journal Article |
Year of Publication: | 1987 |
Authors: | Nilsson, SG |
Journal: | Journal of Animal Ecology |
Volume: | 56 |
Issue: | 3 |
Date Published: | 1987 |
ISBN Number: | 00218790 |
Keywords: | Sitta, Sitta europaea, Sittidae |
Abstract: | (1) A resident population of nuthatches was counted for 12 years both in autumn and spring, whilst reproduction in natural tree holes was followed for 8 years. (2) Survival of adults was 85% between 1 April and 1 November but only 54% between 1 November and 1 April (46% on an annual basis). (3) Spring population size was positively related to winter temperatures and to winter food supply measured as the size of the preceding beech mast crop. Autumn numbers, but not winter survival rate, were higher when there was a big crop of beech mast. (4) The main density-dependent factor, recruitment of young of the year to the autumn population, was positively related to the current beech mast supply and negatively to the density of adults. Number of young fledged had no effect on autumn recruitment. (5) Territories with relatively high breeding success were more frequently occupied than low quality territories. An eightfold increase in density of breeding pairs reduced the per capita breeding success by half. Part of this reduction was due to a lowered mean territory quality. (6) Winter appears to be the limiting season, since most mortality of adults occurs then, but all density-dependent, i.e. regulatory, factors occur before winter. |
URL: | http://www.jstor.org/stable/4957 |
Short Title: | Journal of Animal Ecology |
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