Use of hunters in wildlife surveys: does hunter and forest grouse habitat selection coincide?

Wildlife monitoring performed by volunteer personnel may suffer from bias with regard to their habitat use. Such errors can lead to erroneous population estimates, evidently influencing both management programmes and research that are based on the monitoring. We used a dataset on hunters' habitat use in forest while searching for black grouse (Tetrao tetrix) and capercaillie (Tetrao urogallus) to test whether hunters' utilisation of the habitat was independent of that of grouse or if it corresponded to the grouse habitat preference. Twenty volunteer hunters with dogs registered their tracks and all observations of capercaillie and black grouse in stfold County, Norway, during August 2003 and 2004. We performed an ecological niche factor analysis (ENFA) and a K-select analysis with respect to hunters' selection for habitat, described with ecogeographical variables related to forest stand characteristics, as well as the habitat preference of the observed grouse, conditional on the habitat utilisation of the hunters. Individual ENFA on the hunter's tracks revealed large variation in the habitat preferences of the hunters. The K-select indicated few overall patterns in the habitat characteristics of grouse observations, conditional on the hunters selected habitat. Accordingly, the results indicate that hunters' observation of grouse prior to the hunt may give indicators of changes in grouse density unbiased by habitat preference due to the large between-hunter variation in habitat preference, given that a sufficient number of hunters is used. This suggests that such monitoring programmes can provide information about fluctuations in grouse population sizes valuable for both the management and research of forest grouse species.