Le déclin du Grand Tétras (Tetrao urogallus) en Europe : le point de la situation après le colloque international de Colmar et les perspectives de réintroduction dans les Hautes-Fagnes de Belgique

The Capercaillie has disappeared from the Belgian Ardennes at the beginning of the eighteenth century. Several reintroductions in Germany near the border in the late eighteenth and the early twentieth century have allowed some birds to reestablish small local populations which survived until 1933. The question arose as to the opportunity of a reintroduction in the Hautes Fagnes-Eifel Natural park. This problem is examined against the discussions conducted in Colmar in 1981 by two dozen specialists from France, Central and Northern Europe.

The Capercaillie populations are on the decline in most parts of their european range since world war the second, and are near to become extinct in numerous traditional sites in Western and Central Europe, mainly in France, Germany and Bohemia. Factors affecting the population level are diseases, too high game-ungulates densities, atmospheric pollution (sharp rains), disturbance through touristic invasion, but all authors agree that the root of the problem is the development of modern sylviculture implying densification of the forest-roads network, spreading of phyto-sanitary products, and overall splitting and destruction of the habitat. This very sedentary bird needs indeed all its vital recquirements on a small area in mixed heterogenous forests with open wetter spaces for displaying and courting on the lek, dense shrub layer and plenty of preferred plants as food - blueberry shrub especially -, big old trees as roosting sites. Small population isolates disappear here and there.

Numerous reintroduction programms have been conducted in the past 150 years. Very few succeeded, as in Scotland; most failed ! A special interest is granted to a raising experiment in progress in order to reintroduce the species in the Massif central in France, from where it disappeared two centuries ago; the young birds are released as soon as they have completed their post-juvenile moult, in a good heterogenous regenerated and planted forest; good attention is paid to the ontogeny of the behaviour and the adaptiveness of the birds to their new habitat. The aim is to produce enough birds to allow the building up of at least one reproductive social unit.

Nevertheless, if the species is to be saved in those places from where it has not yet vanished, its vital habitat recquirements should be taken into consideration; plantations should be undertaken for long period through natural regeneration with small changes with time in natural ecological successions; clearings, borders should be multiplicated and diversity enhanced. Some experiments are in progress in Sweden, Switzerland and Black Forest of Germany, in order to achieve a compromise between conservation and economic recquirements. In France, forest management recommandations have been formulated by the national forestry service, since foresters are responsible for the structure and quality of the habitat: plant composition of the differents layers, importance of the clear-cuttings, length of the forest exploitation cycles.

From all these considerations and experiments, it seems clear that conditions for a successful reintroduction of capercaillie in the Hautes-Fagnes are not prevailing at the present time. We need first to controll the public invasion and to improve the habitat suitability. But contacts with consultants and follow up of the Cevennes programme should be wellcommed.