1. Department of Renewable Resources; University of Alberta; Edmonton AB Canada
2. Yukon Research Centre; Yukon College; Whitehorse YT Canada
3. Departamento de Biología de la Conservación; Estación Biológica de Doñana (CSIC); Sevilla Spain
4. Centre for Applied Ecology “Prof. Baeta Neves”/INBIO; Institute of Agronomy; University of Lisbon; Lisboa Portugal