Multi-breeding in a wolf pack. Nowadays it is commoner than breeding of a pair in Naliboki Forest

Co-author Irina Rotenko

Multi-breeding in a wolf pack is one of the enigmatic questions of the grey wolf reproduction. When we began to investigate the wolf reproduction in Belarus (mainly in Naliboki Forest and Paazierre Forest) in details, we found the phenomenon of a pack multi-breeding.

Till 2019 we gained more or less detailed information about denning of 59 wolf breeding groups (i.e. pair or a complex breeding group that consists of two breeding females and adult male, at least) in Paazierre Forest in the northern Belarus and in Naliboki Forest in the central-western Belarus. Also, an autopsy of all wolves from nine whole packs, which were killed in March-early April in 1997-1999 in Paazierre Forest, was fulfilled. So, the revealed phenomenon of a pack multi-breeding was proved by both searching for wolf dens (19 cases of a pack multi-breeding were found) and wolf carcass materials (2 cases of a pack multi-breeding were found).

In 17 cases there were mainly double-breeding (i.e. there were two breeding females in a complex breeding group), and in two cases we found triple-breeding (Sidorovich & Rotenko, 2019). So, till 2019 we revealed 19 cases of the phenomenon, and 17 out of the 19 cases were registered in the conditions of a low density of the whole wolf population (i.e. living not only in Naliboki Forest or Paazierre Forest but in the larger region, which included these forest massifs). As to food base at breeding, in 12 cases the prey stock was poor or moderate, and only in 7 cases the food base was rich. From these results we concluded that the phenomenon of pack multi-breeding is a density-dependent reproduction regulation in wolves (Sidorovich & Rotenko, 2019). Also, we suggested that richness of prey stock is not a key factor that conditions multi-breeding in wolf packs.

Wolf pups from two different litters, which were situated at the distance of several hundred metres. Both litters at the moment we discovered them consisted of bigger and smaller pups, because mothers took pups from each other.

The gained data suggests that till 2019 a pack multi-breeding happened in 32% of cases (denning information) or 22% of cases (carcass information). At the same time, we guessed that we could underestimate these values, because some of the cases of pack multi-breeding could not be revealed especially before 2015. In the case of denning data not all dens could be found, whereas concerning the carcass materials not all members of those nine packs could be killed.

Since 2015 in Naliboki Forest we have studied on a pack multi-breeding in wolves with enough accuracy by investing huge efforts and knowing a lot about wolf breeding behaviour in that forested terrain. In total, during nine years (2015-2023) we traced 24 wolf breeding groups (11 pairs and 13 complex breeding groups). During these nine years we investigated 38 breeding stories in details. There were discovered 11 dens with pups of breeding pairs. Concerning a pack multi-breeding, we found 12 cases of double-breeding and one triple-breeding in a complex breeding group. Thus, in 2015-2023 in Naliboki Forest a pack multi-breeding appeared to be really common, and it happened in 54% of the studied cases. So, pack multi-breeding got commoner than breeding in pairs there. It is also worthwhile to notice that during the whole this period (2015-2023) the wolf population density in the whole large region was mainly low, while food base for wolves in Naliboki Forest was moderate (more red deer, but markedly fewer beavers and roe deer than it is used to be).

Here we also would like to state that wolf-dog hybridisation in Naliboki Forest and the whole Belarus can be not responsible for the revealed phenomenon of a pack multi-breeding in wolves, because we found this breeding peculiarity in wolves (i.e. a pack multi-breeding; 6 cases in the denning data and 2 cases in carcass materials) before the hybridisation began. At that time wolves in Belarus were genetically unpolluted by stray dogs. In the early 2000s we sampled many wolves in Belarus (in Paazierre Forest and Naliboki Forest inclusively) for a genetic study, and none of these wolves showed even a dog ancestry (Stronen et al., 2013). Maybe the on-going wolf-dog hybridisation conditions somehow a pack multi-breeding, but definitely it is not the initial cause. However, it is still a question to investigate.

In the whole, the phenomenon of a pack multi-breeding in grey wolves in Eurasia is a “golden mine” for a researcher of the species. Still there are so many pressing questions in that. How such complex breeding groups are formed? What is a blood relationship between breeding females in a complex breeding group? Are they either mother and daughter or sisters or non-relative subordinated females? Why in some complex breeding groups there are two and even three big males, who demonstrate independent and simultaneously peaceful behaviour to each other and how that peculiarity connects with a leadership (male or female) in a complex breeding group? Which factors determine the distance between different litters in a complex breeding group and why it varies so much from several hundred metres till several kilometres and changes frequently? Why do mothers try to steal pups from each other? What is an order of hunting and feeding pups in a complex breeding group? This list of questions could be continued.

Actually, the deeper we learned the details of a pack multi-breeding in grey wolves, the more it looked like a mess without a strong consistency. Breeding stories were so distinctive. However, one day we have realised that the main consistency in that breeding mess is to provide possible maximum of offspring at all costs. Interestingly, was it evolutionary formed or did it appear secondary as a demography adaptation to the severe long-term persecution by human beings?

Finally, one hardball question we would like to raise. According to our current thought, a pack multi-breeding in grey wolves, perhaps, happens everywhere in Europe and Asia, but simply it still unknown. To find out this breeding phenomenon, long-term huge efforts should be invested in the same well-known terrain by a smart way. Maybe we are wrong, but still we hardly know any other such detailed study on breeding in grey wolves in Europe or Asia that could be able actually to reveal this phenomenon of a pack multi-breeding detailed enough. Perhaps, that was just missed due to not enough concentration on this question and insufficient efforts and skills. What do you think about?

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