Difficulties in detecting habitat selection by animals in generally suitable areas

Species/habitat relationships and their responses at different scales are i mportant aspects of ecological and conservational research. We studied the occurrence of hazel grouse Bonasa bonasia males in a forest reserve over a 10-year period at varying scales and population densities, using two sets o f habitat descriptions. Avoidance of pine Pinus sylvestris was the only hab itat effect in the hazel grouse/habitat analyses that was significant throu gh all scales, seasons and densities. Thus, in spite of long-term data on a well-known species and detailed vegetation descriptions, only a few clear patterns relating to hazel grouse habitat selection were found at the relat ively small scales analysed. We conclude that the non-significant relations hips were due to the generally suitable composition and small variation of habitats within the study area, and that significant results may not be exp ected within the scales analysed and with the methods used. Thus, to find a ssociations between animal species and habitats, a suitable study area must include a certain degree of habitat variation and the relationships should probably be examined at a scale equal to or larger than the home-range of the species in question, or considerably larger if population data are avai lable. The results are discussed in relation to other studies and the appli cability of the habitat descriptions and census techniques for conservation of hazel grouse populations in managed forests are discussed.