Every time rereading the excellent wolf monograph by Mech and Boitani (2003), in particular, the item about wolf communication by Harrington and Asa, I was surprised to find out how rich voice-communication of wolves in North America and somewhere else can be. In my study areas in Belarus (look like in the whole country) I can characterize wolves as non-howling let’s say silent. More and more I become convinced that wolves in Belarus avoid to produce any loud noise.
Population decline of carnivore species may happen suddenly, develop rather fast and proceed short-term. For instance, such demise character was known for the European mink in Belarus and Russia (Macdonald et al., 2002; Sidorovich, 2011). Population decline of other carnivore species may pass gradually and less evident, and a considerable decrease in population density may take many more years.
The situation that is characterized by gradual and long-term decline is fairly hard to notice, while manipulating short-term data only. It takes much time to establish a right hypothesis on the decline and to prove the hypothesis. Usually, in such a case, when a population decline appeared to be evident, it is already too late to get a complete dataset to analyze the declining process and to reveal the factors that impacted the population. The polecat Mustela putorius population decline in Belarus was characterized by the mentioned features of gradual and long-term decline (see Sidorovich, 2011). Our results of the study on the polecat demise suggest the following negative factors that are responsible for the population decline.
A year ago, while publishing the book about badgers and raccoon dogs in Belarus (“Badger and Raccoon dog in Belarus: Population studies with implication for the decline in badgers“, Minsk, 2017), it looked like we knew all possible ways of interference between raccoon dogs and badgers. We registered blocking badgers sleeping in the sett’s hibernating chamber by raccoon dogs with suffocating of the badgers afterwards; killing of badger cubs by raccoon dogs; non-effective attacks of badger on raccoon dog at its sett as well as a lot of marking of badger setts by both species in order to prevent usage of the sett by the burrow-competitor species. Any attack of an active badger by raccoon dogs was not registered, and that was considered as something non-real.
In one of our study area on the question, which is the Lovat terrain in Paazierre Forestin northern Belarus, both riparian vole species (the water vole Arvicola terrestris and root vole Microtus oeconomus) have become scarce since the American mink Neovison vison has established a dense population. Continue reading “Impact of American minks on water vole and root vole populations and populations of the aboriginal predators – eaters of these beneficial prey, in particular, the stoat and great grey owl”
Having pronounced construction instinct and activity, beavers change a lot their aquatic habitats in order to provide foraging pathways protected by water environment and create effective shelters saving them from enemies (mainly wolves and humans) and cold weather during overwintering, giving birth and raising a litter as well as everyday resting.
With respect to semiaquatic mustelids i.e. otter and mink, a question arises do these changes in aquatic habitats bring benefit for them or not? Beavers build a lot of shelters in kinds of burrows and lodges, and such a benefit of better sheltering environment for otter and mink is evident. While investigating the question, we were mainly interested in beaver activity-related increase of water-dwelling prey of otter and mink in aquatic ecosystems and, first of all, in small streams such as small rivers, brooks and drainage canals. Just at small watercourses such an effect of damming by beavers on semiaquatic mustelids may be the most pronounced. By building dams, beavers create ponds; such ponds are gradually eutrophicated and densely overgrown with macrophytes. So, it was essential to get know, such beaver ponds bring benefit in aquatic prey supply for semiaquatic mustelids or not, and if it is, on which stage of the pond eutrophication such benefit is the highest.
The main monograph on the grey wolf by Mech and Boitani (2003), which still provides the basic and unequalled knowledge on the species biology, informed the following. “Almost 30 years ago, Keith (1974) concluded that “the factors which provide wolf pup mortality during the first 5 months are almost wholly unknown. This is probably the single greatest enigma in wolf biology today.” Though some strides have been made toward identifying these factors, this is still a much needed area of research.”
While reading this in 2004, we already were much aimed by the question. Moreover, the opportunity to find out something really new in the wolf biology accelerated these our research efforts. Nowadays, we may say that, at least, for the region of Belarus mortality in wolf pups is known more or less. Also, we assume that the factors, which impact the survival of wolf pups in Belarus, act in other regions of European forest zone. At the same time, we suppose that the only main causes of wolf pup mortality were found out, whereas many smaller questions remain unresolved.
Within the analysis of vertebrate predator-prey community we carried out the population studies on the badger Meles meles and raccoon dog Nyctereutes procyonoides with implication for the strong decline in badgers even in seminatural terrains in Belarus. Continue reading “What is the cause of the badger population decline in Belarus? “