Understanding the effects of harvesting willow ptarmigan Lagopus lagopus in Sweden

Willow ptarmigan Lagopus lagopus is considered a popular small game species by many hunters in Scandinavia. A simple harvest strategy would be to prohibit harvest in parts of the total area. We used a spatial model of a fluctuating population of willow ptarmigan, divided into 25 subareas to investigate the possible advantages of buffer zones in managing harvest. We let the breeding success be the source of annual environmental stochasticity but without any spatial variation. Survival was assumed to be density dependent over the total area, whereas dispersal was modelled as density independent. We then compared four major scenarios in which we let dispersal and harvest vary. About 75% of the area could be left open to hunting even if the level of harvest was close to the extinction level if executed in all grids. This harvest strategy would be particularly advantageous if the goal is to provide as many hunting opportunities as possible, rather than to harvest a maximum sustainable yield. Furthermore, it is quite simple and does not need a resource-demanding control system. We believe that a harvest strategy which sets aside a part of the area as a buffer, and places a limit to the harvest effort in the grids that are open for hunting, would be a cost-efficient system with only a small risk of overharvesting.