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Small-scale spatial dynamics in a fluctuating ungulate population |
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| Authors: | Tim Coulson† Steve Albon‡ Jill Pilkington§ Tim Clutton-Brock¶ |
| Institution: | Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK;;Institute of Terrestrial Ecology, Hill of Brathens, Glassel, Banchory, Scotland, AB31 4BY, UK;;Institute of Cell, Animal and Population Biology, University of Edinburgh, EH9 3JT, UK;and;Department of Zoology, Downing Street, University of Cambridge, CB2 3EJ UK |
| Abstract: | 1. The scale at which population dynamics are analysed is important, as results from analyses at different spatial scales can differ and affect interpretation. 2. In this study, detailed census data collected over a 10-year period from a population of Soay sheep ( Ovis aries L.) on the Island of Hirta in the St Kilda archipelago, Scotland, is used, together with cluster analysis, to distinguish a temporally stable spatial substructure. 3. Structured demographic accounting of the variance in population change (SDA) is also used to analyse the dynamics of the whole population treated as (a) one unit; (b) one unit subdivided into three subunits; and (c) three independent units. 4. Differences in survival, recruitment and dispersal rates are demonstrated between divisions of the population, which are probably associated with variation in grazing quality. 5. If these groups were not coupled by dispersal and density-independent entrainment, the population dynamics of the three groups would diverge, however, the dynamics of the three subunits are strongly correlated. |
| Keywords: | age class dispersal recruitment Soay sheep spatial heterogeneity |