We assessed the diet composition of wolves inhabiting Notecka Forest (ca. 1,400 km²) in Western Poland based on the analysis of scats (n=261) collected in 2008-2021. The study revealed that wolves in this large forest tract, consisting mainly of pine monocultures, consumed primarily wild ungulates (95.2% of consumed biomass). The roe deer was the essential food item (47.8%), followed by the red deer (Cervus elaphus) (25.1%) and the wild boar (Sus scrofa) (18.4%). Wolves supplemented their diet with medium-sized wild mammals, mainly the European hare (Lepus europaeus) (2.8%) and the Eurasian beaver (Castor fiber) (1.9%). The food niche was narrow (B=1.1), and there was no difference in food composition between the spring-summer and autumn-winter seasons. We emphasize the significance of the smallest European wild ruminant, roe deer, in the diet of wolves inhabiting Central European Plains.

We estimated the composition of the wolf diet by analyzing the content of their scats (n=261) collected opportunistically across the entire Notecka Forest, Poland, from 2008 to 2021. Fieldwork was performed within long-term projects dedicated to the assessment of population dynamics (Nowak and Mysłajek 2016), habitat selection (Nowak et al. 2017), and genetics (Hulva et al. 2018, Szewczyk et al. 2019, Kloch et al. 2021) of wolves recovering in Western Poland. The gathering of samples over many years allows us to take into account long-term fluctuations of wild ungulate numbers. Scats were collected while walking or driving along forest roads, and special attention was paid to junctions of roads often used by wolves for marking territory (Stępniak et al. 2020). Such an approach gives the same results as the analyses of scats collected at home sites or at clusters of telemetry locations (Gable et al. 2017). Scats were identified based on size, shape, and location near wolf tracks and ground scratchings (Jędrzejewski and Sidorovich 2010). Along with studies on the diet composition, the authors also conducted studies on wolf genetics, thus from fresh scats, non-invasive genetic samples were taken and subsequently analysed using a fragment of mitochondrial DNA and a set of autosomal microsatellite markers to ensure proper identification of the species – see Hulva et al. (2018), Szewczyk et al. (2019) and Kloch et al. (2021) for further details. Collected scats were placed in paper envelopes and dried in a laboratory drier at 70°C for five days to kill parasites often recorded in feces (Popiołek et al. 2007). Subsequently, scats were soaked and washed on the dense sieve. The remaining elements – hair, fragments of bones, teeth, hooves, etc. – were used to recognize food items eaten by wolves. Prey species were identified using hair (Debrot et al. 1982, Teerink 1991, De Marinis and Asprea 2006) and skull (Pucek, 1984) identification keys and reference material.