The impact of predator abundance on grouse populations in Finland-a study based on wildlife monitoring counts

Abstrakti

The relationships between grouse (Capercaillie, Black Grouse and Hazel Grouse) populations and red fox and pine marten abundance were studied in Finland using the wildlife triangle counts from 1989 to 1999. Spatially, a negative relationship existed between predator indices and grouse breeding success, but predator indices and grouse density did not correlate. When temporal variation was concerned, there was a negative relationship between the fox index and grouse breeding success in some areas of southern and western Finland, and between the marten index and grouse breeding success in north-east Finland. Only in 4 areas out of 27 was there a negative relationship between predator indices and grouse density, all areas being in northern or eastern Finland. The growth rate of grouse populations had a stronger negative relationship with grouse density than with predator indices; predator numbers thus were of minor importance when determining the trends in grouse populations.