Food habits of the wolfCanis lupusin Latvia based on stomach analyses

Abstract

INTRODUCTION Foraging of the wolf Canis lupus is fairly well studied for the Palaearctic and the North American range (Bibikov, 1985; Pavlov, 1990; Jedrzejewska & Jedrzejewski, 1998; Mech, 2003). The few studies conducted in the Baltic region (Valdmann et al., 1998, 2005; Andersone, 1999; Andersone & Ozolins, 2004) confirm the existing knowledge; however, they have significant implications related to the species conservation policy. Wolf conservation is a totally new and comparatively lately implemented initiative for the Baltics and Latvia in particular (Ozolins, 2001, 2006). Nevertheless, the wolf population has never been assessed as endangered. Promotion of wolf killing by paying bounties was abolished in 2000 while the legal restrictions on hunting, including a short ban during the breeding season, were introduced for the first time in 2004. Due to the never disrupted human--wolf coexistence in this area, the so-called wolf conflict is rather moderate and mainly related to the fear of the hunters that any protection measures towards wolves will reduce their bags of wild ungulates or just make them harder to hunt. Livestock depredation is considered probably to less extent than elsewhere as preventive measures are so far completely ignored by the farmers despite the fact that tens of sheep and cattle are killed annually. Since 1998, the policy makers have succeeded in involving most of the relevant stakeholders in a joint wolf population monitoring that provides data on its current distribution, demographic viability, and records of damage to livestock. Since 2004, these data have been used in order to adjust the wolf hunting quota to the actual population status to enable sustainable wolf harvesting. The point of interactions between the wolf and other game species persists hence all details of wolf diet and amount of consumed prey are important to deal with controversial interests of wildlife managers. This study examines the food eaten by wolves, who afterwards were killed by hunters so that the sex, age, date of hunting, and place of individuals are known. As hunting pressure may change the demographic structure of the wolf population (Bondarev, 2002; Mech, 2003) it is important to understand how far and whether at all it has consequences in foraging, which is the main reason of the 'wolf conflict' (Treves & Karanth, 2003). Our latest material will help to make a temporally and spatially related analysis on wolf diet and prey consumption for quite a considerable time period because preliminary data were gathered and summarized already from 1998 to 2001 (Andersone & Ozolins, 2004). At that time wolves were persecuted without any restriction and ungulate populations just started to recover after the fast decline in the 1990s (Andersone-Lilley & Ozolins, 2005). Recently, ungulate populations have shown an obvious increase and the wolf population is controlled at a more or less stable level. Thus we expected some changes in the wolf diet as well. MATERIAL AND METHODS Food habits of wolves in Latvia were studied from December 2001 to April 2008. The study was based on analyses of 165 stomachs obtained from harvested wolves all over the country. As wolves were rarely hunted in the summer season, there were only 17 stomachs from this time of year. Therefore differences between summer and winter diets were not analysed. Food remains were found in 121 stomachs. Fresh stomach contents were weighed (1 g precision) and microscopic slides of hair found in stomachs were prepared in order to identify prey species according to the keys by Teerink (1991) and our own reference collection. In our former (Andersone & Ozolins, 2004) as well as recent experience, in the majority of cases the contents of wolf stomachs consist of remains of a single prey species. As a maximum, remains of two different prey were found in the same stomach. Eleven samples contained two food items including plant remains. …