DISPERSAL, COLONIZATION POWER AND METAPOPULATION STRUCTURE IN THE VULNERABLE BUTTERFLY PROCLOSSIANA-EUNOMIA (LEPIDOPTERA, NYMPHALIDAE)

1. Mark-release-recapture (MRR) surveys of Proclossiana eunomia conduc ted in 1992 and 1993 in the Belgian Ardennes, and in 1993 in the Pyren ees revealed that 8-16% of recaptures occurred after a movement of mor e than 200 m on unfavourable habitat. 2. The spread of P. eunomia foll owing its introduction in Morvan (central France) 20 years ago shows a colonization speed of 1-3 km per favourable year (i.e. sunny weather during the image flying season) and average 0.4 km year(-1) over a 25- year period. 3. Both MRR and introduction studies suggest a hierarchic al nested metapopulation structure, movements being free within habita t patches, common between neighbouring patches and significant between river basins, ensuring population cohesion at the regional scale. 4. The establishment of a network of populations (metapopulation) within 5 years of the original introduction shows that (re)colonization of em pty habitat patches around refuge/introduction sites may be effective and quick. High dispersal rate as well as the dynamics of P. eunomia's metapopulations suggest that a network of suitable habitat patches is necessary for the long-run conservation of this vulnerable species.