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Doctoral thesis, 2011

Grouse - habitat relationships

Lande Unni Støbet

Abstract

Fennoscandian grouse populations are facing habitat degradation and are in decline, though not to the same degree as in western and central Europe. To be able to identify factors causing population decline and initiate proper management actions, a well functioning monitoring program and management are essential. In this thesis I have used datasets on capercaillie, black grouse and willow ptarmigan. The datasets were sampled through large scale monitoring programs by volunteers. The volunteers were mainly hunters that already had field-experience and knowledge of grouse, and could do the work at low cost and with few logistical problems. I found that using a GPS to measure perpendicular distances less than 50m from line transects reduced the reliability of the density estimates. Adding covariates such as habitat (open or closed), and flushed by dog or handler, improved the models of density estimates. In non-systematic sampling designs where hunters were free to go wherever they wanted during sampling, I found little bias in the habitat selection of hunters compared to that of capercaillie and black grouse, probably caused by the diversity in habitat use among the hunters. This indicates that such sampling of data can also provide unbiased indices of population density, given a sufficiently high number of hunters is used for monitoring. Based on the adult density and chick production from the density estimates, I found a positive relationship between the heterogeneity of the landscape and both adult density and chick production of capercaillie and black grouse. Forest of moderate to high productivity had a positive effect on adult density of both species while contrary to expectation the proportion of old forest seemed to have a negative effect on chick production of both species. I did not detect any clear relationship between willow ptarmigan and habitat at either the individual or the landscape scale. However, at the population scale habitat relationships were detected. Together, these results suggest that methods for monitoring grouse species are quite reliable, but could be improved by rather simple additions. Moreover, habitat composition seems to generate differences in demographic rates and population densities among populations, but these are not detectable at the individual or landscape scale. This suggests that management of grouse species should be done at a scale that captures the heterogeneity in the landscape, most likely over larger areas.

Keywords

grouse; tetrao; lagopus; habitats; population decrease; monitoring; management; scandinavia

Published in

Acta Universitatis Agriculturae Sueciae
2011, number: 2011:03
ISBN: 978-91-576-7572-9
Publisher: Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences

Authors' information

Lande, Unni Støbet
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies

UKÄ Subject classification

Ecology
Fish and Wildlife Management

URI (permanent link to this page)

https://res.slu.se/id/publ/32366