Nowadays in Naliboki Forest wolves den almost exclusively in burrows

Coauthor Irina Rotenko

In June of 2018 there was post “Trends in the denning behaviour of the wolf and lynx in connection with the changes in the vertebrate community in Naliboki Forest (north-western Belarus)”. During the previous two years (2017 and 2018) in Naliboki Forest, the central-western Belarus we noticed several changes in the denning behaviour of wolves under the conditions of the markedly increased population densities of red deer and bison and still quite high number of elks. Bison, elks and red deer, while finding wolf pups, tend to kill them by trampling. The higher number of these animals that are inimical for wolf denning, the more protective reactions of wolf breeders we expect.

In June of 2019 in a separate post we reported about the next step in the change of wolf denning habitats in connection with further increase in red deer and bison numbers in Naliboki Forest. One of the protective response of wolf breeders appeared especially evident and we described that. In particular, the main denning habitats became pine or mixed pine-spruce stands on dry lands almost without fallen trees and with poor forest floor. In such forest patches there were registered the minimal abundance of tracks of wild ungulates, while all known treefalls were densely occupied by red deer, elk and bison mainly for breeding, and all burrows were densely occupied by badgers. Here it worthwhile to notice that in Naliboki Forest treefalls and badger setts were basic denning sites of wolf breeders before. In  pine or pine-spruce stands that are mostly rather open  habitats in Naliboki Forest parent wolves made mainly cavity-dens that were about one meter long. Approximately a quarter of wolf dens were made in kind of burrows up to 4 meters long. Before these wild ungulates reached high numbers, parent wolves, while denning, created mostly couch-dens and pit-dens in treefalls, as well as they enlarged entrances in badger setts making like a cavity-den.

In May 2020 under the conditions of the further increase in red deer and bison and presence of many elks we observed the further change in denning tactics of parent wolves. They started denning almost exclusively in quite deep burrows up to 5 meters and well-protected underground cavities improved by digging for 1-1.5 meter again like a shorter wide burrow. During May we used to find 2-7 wolf burrow-dens only, whereas there were at least double more breeders. In May 2020 we discovered 2-5 newly created wolf dens daily. Almost all the active dens of wolves were situated in such burrows. In May 2020 we faced with same habitat preference to place dens as during breeding of the few last years. However, wolf breeders became to den in badger setts more frequently because of slightly decreased number of badgers and perhaps stronger wishes of wolves to place litter in a safely sheltered site like a deep burrow.