ESTIMATING THE MINIMUM POPULATION-SIZE THAT ALLOWS A GIVEN ANNUAL NUMBER OF MATURE RED DEER STAGS TO BE CULLED SUSTAINABLY

1. The management of ungulate populations for sport in the presence of potentially conflicting interests such as conservation, either of the animals or of the habitat they use, may be formulated as a problem of optimization subject to constraints. 2. A deterministic simulation mo del was developed to assess optimal culling strategies for Scottish re d deer. The aim was to allow deer population size to be reduced while maintaining a given annual cull of mature males (stags). 3. To achieve the above aim, the model indicated that the female (hind) cull should be restricted to non-lactating adult (yeld) and immature hinds. 4. If , instead, only calf and hind pairs are culled, the population size mu st be roughly 14% larger to achieve the same cull of mature stags. 5. Under ideal conditions, it seems possible to reduce hind numbers so th at there are just two hinds of age greater than or equal to 1 for ever y stag of age greater than or equal to 6 in the population, provided t hat the population is maintained well below the maximum sustainable si ze (carrying capacity). Under this strategy, the model indicated that the ratio of stags of age greater than or equal to 1 to hinds of age g reater than or equal to 1 should be between 1.5 and 1.8 to 1.0. 6. In principle, for populations well below carrying capacity, for every 10 mature stags to be stalked annually, it seems possible to reduce numbe rs such that the summer population comprises just 70 stags, 40 hinds a nd 20 calves. 7. In practice, limited culling of hind and calf pairs a nd young stags for quality control or other reasons, together with the need for a margin of safety, dictates that the hind population should be rather larger than this. However, on most estates in Scotland, hin ds currently outnumber stags by roughly 2:1, so that our results sugge st that large decreases in numbers of hinds can be achieved without in curring a loss of revenue from stalking. 8. If the market expectation were to be changed so that hunters wished to stalk stags regardless of age, rather than just those with perceived 'trophy' value as mature a nimals, the same number of deer could be stalked at an even lower popu lation density, to the benefit of other land uses.