Over the past few years, ecologists and woodland workers have noticed that the pressure exerted by the grazing of wild cervidae has become a threat for the whole of the temperate forest of the northern hemisphere and for a number of Boreal forests. Species of cervidae that were rare at the beginning of the century in Europe and in America now are so abundant that they prevent regeneration of forest after clearing or after natural disturbances. They damage shrubs, completely destroy vulnerable herbaceous plants and modify the structure of timber stands to the point where they affect other animal species, including birds and insects. The white-tailed deer (Odocoileus virginianus), the moose (Alces alces), the red elk (Cervus elaphus), the mule deer, (Odocoileus hemionus) and the roe deer (Capreolus capreolus) are the main species responsible for this ecological and economic damage.

There are a number of causes for this great pressure on the milieu and they are often interlinked, though they do vary according to location. However, the absence of any effective predators, such as the timber wolf (Canis lupus) may generally be seen as a promoting factor. In Sweden, the moose is a major threat for coniferous forests. However, over the past years, the roe deer population has grown to the point of constituting almost as great a problem and moreover it also attacks the deciduous forests. It is estimated that annual damage caused by wildlife to the Swedish forestry industry is about 500 $ CDN, million. The almost complete absence of the wolf over many years, forestry practices that have favoured the moose, and relatively mild winters seem to explain a good part of the problem. In Canada, where the major part of the moose distribution area overlaps the wolf distribution area, a fairly generous hunting policy has allowed the population to be kept down to a safe level as regards forest regeneration. In Newfoundland, where the moose was introduced at the beginning of the century and where the wolf has been exterminated, the pressure exerted by the moose does sometimes have a tangible impact on the regeneration of the balsam fir (Abies balsamea).

In Quebec, the white-tailed deer of the Anticosti Island has practically eliminated the deciduous shrub stratum throughout the island and has also completely prevented regeneration of the balsam fir. Since the white-tailed deer was introduced, in 1896, it has caused the disappearance of 50% of the fir stands on the island and what remains will suffer the same fate a few score years down the road. In fact, the deer seems even to have got rid of the previously abundant black bear (Ursus americanus) by reducing the number of fruit-bearing shrub. The total absence of predators, the introduction of the deer into an environment where there is no competition and the seashore climate all probably explain the successful development of the white-tailed deer on the island. In fact, the deer populations in the south and the west of the province have probably never been as high as they are now.

Similar situations will be found in a number of national, Canadian and U.S. parks. In some cases, Yellowstone Park, for example, the wolf has been reintroduced in order to restore an ecological balance. Wild cervidae have also become a major cause of highway accidents and of damage to landscape, architecture and cultivated farm crops. Fruit trees and shrubs are greatly sought after during the winter period. The extent of the impact of these high cervidae populations has been a wake-up call for wild life management to find solutions.

So far, we are far from these solutions. Locally, the only effective means is to use fencing to protect vegetable gardens, gardens, roads or forest regeneration, as on the Anticosti Island. This is extremely expensive, in fact often prohibitively so. The reintroduction of predators is only possible in rare cases, such as Yellowstone, and its success is far from being obvious. It is also difficult to argue in favour of such programs when talking to local farmers. Contraception for the female white-tailed deer has been tried out for a number of years, but it is expensive and so far not very efficient. The capture or selective slaughter by wildlife agents is also expensive and is only used when there are safety problems in the suburbs.

Sports hunting turns out to be the least expensive and the most effective management tool outside inhabited zones. However, the number of hunters has shown a tendency to drop off over the past years, while the number of deer that survive the winter has increased because this season has been less severe due to global climate changes.

In conclusion, we may expect that the problems related to the high population of cervidae in the temperate and boreal forests will grow in severity if the tendency to moderate winters is maintained and if the drop in hunting continues as it has over the past years. We will probably have to learn to live with the new situation while looking for new paths to solutions. Already, a number of residents of the Island of Vancouver have opted to use only deer resistant plants when creating their landscape architecture. Some producers of ornamental plant seeds do in fact indicate in their brochures those plants that are deer-resistant.
 
Jean Huot, professor
Biology Department

Laval University
Quebec City (Québec)