Small-scale spatial dynamics in a fluctuating ungulate population

1. The scale at which population dynamics are analysed is important, as res ults from analyses at different spatial scales can differ and affect interp retation. 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 S t 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 whale population treated a s (a) one unit; (b) one unit subdivided into three subunits; and (c) three independent units. 4, Differences in survival, recruitment and dispersal rates are demonstrate d between divisions of the population, which are probably associated with v ariation in grazing quality. 5. If these groups were not coupled by dispersal and density-independent en trainment, the population dynamics of the three groups would diverge, howev er, the dynamics of the three subunits are strongly correlated.