Beaver: A New Prey of Wolves in Latvia?

Abstract

The number of wolves in Latvia increased from 230 in 1985 to 997 in 1997. At the same time the population of wild ungulates declined significantly. The aim of this study was to examine the food habits of wolves in different seasons and to determine the ratio of wild ungulates in the diet. It is of special interest because no such study has ever been conducted in Latvia. Forty-one scats and 13 stomachs of hunted wolves were collected in the winter and summer of 1997. Scat analysis followed standard procedures. Microscopic analysis of hair was used to identify mammal species. Cervids (elk, red deer, roe deer) were not specified separately. Occurrence of particular food items (F%) and biomass of the prey consumed (B%) were calculated. In winter, the wolf diet consisted mostly of cervids (ca. 60%), wild boar, and livestock consumed as carrion. In summer, the ratio of cervids in scats was lower (48.5 F% and 31.4 B%) than it was in winter due to a more variable food content. Based on biomass beaver was the most important food item in summer (30.3 F% and 36.1 B%), followed by cervids, and wild boar (18.2 F% and 30.1 B%). Other food items (small mammals, birds, berries etc.) were of little importance. Thus, wild ungulates are the basic food for the Latvian wolf population in the both seasons. However, the sudden increase of beaver in the summer diet suggests switching by wolves to a more available prey during the depression of the ungulate populations.