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.
Nevertheless, recently in March 2018 in Naliboki Forest I met very interesting tracks suggesting that badger was horribly attacked by a raccoon dog pair. Not a small badger was feeding on the distance about one kilometer from its sett, when it was attacked by two raccoon dogs. The badger was defensing, by snuggling the back to the small spruce, but the raccoon dog forced it to escape. While escaping the badger was slightly blooding. The raccoon dog were running after the poor badger, stopped it and attacked second time on the forest road among the recent clearcut. The badger began running away again, but they caught up it and attacked it on the forest road again. In both places there were a lot of trampled spots of their fighting. The badger escaped again, and the raccoon dog were running after the badger. In the forest habitat, to where the badger went away after the third encounter, there was not enough snow cover to continue snowtracking.
In our (my wife and collaborator Irina Rotenko) book in relation to badgers and raccoon dogs in Belarus (“Badger and Raccoon dog in Belarus: Population studies with implication for the decline in badgers“, Minsk, 2017) we consider the full data set concerning interferential relations between the badger and raccoon dog, what was registered by us in Belarus. Also, we raised the question of whether interspecific pressure from territory marking to direct aggressive encounters impacts the badger population so much and leads to the demise in badgers. For the study we used the following methods: radiotracking, snowtracking, numerous multianual inspections of badger setts, polling experienced workers of game and forest husbandries by means of questionnaire survey or direct interviewing.
Burying of badgers in their setts by raccoon dogs during badger’s torpor
We got several evidences (at least, from two experienced responders out of 174 those surveyed) that raccoon dogs buried badgers being in a torpor in their setts. We questioned only those, who had a great experience with badgers from hunting with earth dogs or from working for a long time for game or forest husbandry or in the field of nature conservation.
The mentioned buried badgers were found by the hunters, while hunting raccoon dogs or hunting badgers before the species was included in the list of protected species. Those individuals were apparently in external good condition, without injuries and signs of depletion. Actually, the badgers were buried by blocking the outside holes of the chambers, where they slept, by ground.
During our own telemetry studies on badgers and raccoon dogs in the Haradok, Vierkhniedzvinsk and Valozhyn districts there were revealed three cases of badger deaths in their setts during winter. The features of joint overwintering of badgers and raccoon dogs in the sett, absence of any wound on the badger body and the ground-blocked passage from the sleeping chamber to the entrances suggested the fault of the raccoon dogs. They just blocked with ground the passage between the sleeping chamber to the entrances for the length about 0.4-1.1 meter.
During numerous surveys of 57 different badger setts in 2005-2011 (in total 711 inspections), we revealed three cases of similar badger death. They were registered in Vierhniedzvinsk, Rasony and Shumilina districts. There in autumn badgers occupied the setts with 2-6 individuals. Then in early winter badgers went into torpor. In the same setts raccoon dogs hibernated either. Since winter finished there were no signs of badger activity registered at the setts. At the same time there were found raccoon dogs that ate badger remains, which were evidently taken out from the setts.
From the above-mentioned information we are doubtless that indeed raccoon dogs tend to block badgers in their sleeping chamber during badger’s torpor in winter. But why does that happen that raccoon dogs tend to bury badgers, while they are in torpor?
First, it has became a common knowledge that predators of different species tend to use threats against other predators and even kill each other. For instance in Belarus killings of predators by predators happen fairly often and may determinate losses of some part of their populations (Sidorovich, 2011). Therefore, such behavior of raccoon dogs against badgers stays away from being something extraordinary.
Then another question arises how raccoon dogs do this as it is known that they also go in torpor during winter. In fact, raccoon dogs are not fully torpid and the period of raccoon dog torpor lasts shorter than that of badgers. So, they have a lot of opportunities to block torpid badgers in their setts. In this matter it is worthwhile to consider the research data on how long torpor in the badger and raccoon dog lasts.
According to the winter radiotracking data, within Belarus badgers fall into torpor with first stable frost in late November and till late February (the Miensk district) and in more northern areas (e.g. the Haradok district) – until the middle of March. Badger setts examinations for any tracks and signs of activity under usual winter conditions (n=327 within territories of 21 administrative districts) support this. Normally we did not register any signs of badger activity until late February. In the end of February badgers were registered to be active for short periods once per 10 days. From mid March badgers started to be regularly active every 2-4 days. Once the badger activity at the sett was registered in mid January under cold weather conditions. However, this badger died after walking few kilometers from the sett. During uncommonly warm weather conditions in winter 2007-2008, 2013-2016 badgers were active from time to time throughout the whole winter.
According to radiotracking data and winter inspections of setts, raccoon dogs unlike badgers were found to be active from time to time over winter, especially in less cold winters. If winter had common weather conditions and started in usual time, raccoon dogs fell into torpor with first stable frost that usually continued until mid February. Even during this time raccoon dogs slept not so deeply as badgers. They were usually registered with tracks to be active outside their burrows for few hours once per 15 days. Moreover, according to the radiotracking data in the first half of winter raccoon dogs were found to be active relatively often inside their burrows without going outside (in 2% of radiofixations, n = 1032). In late February and later raccoon dogs tended to increase their activity even under severe weather conditions. Furthermore, they already walked far from their burrows (0.3-3.2 km, on average 1.1 km) and covered from 0.8 to 7.7 km, on average 3.1 km. In the second half of winter such activity of raccoon dogs usually was registered once per 2-4 days.
Concerning blocking of torpid badgers in their setts during winter it is also matters how often raccoon dogs use the setts already occupied by badgers. Usually raccoon dogs overwintered in 78-100% of the badger setts checked by us, and this frequency of usage related to the alien species population density.
Thus, raccoon dogs are well placed to block badgers, which being in winter torpor in their setts. We can safely assume that such interactions exist and considerable part of badgers die annually for this reason According to our rough estimate about 10% of badgers die like that each winter. It should be emphasized that raccoon dogs tend to dig in badgers in their sleeping chambers every time they discover them while moving inside the sett. However, nearly a half of badger sleeping chambers have two ways out (according to hunters’ evidences, who got badgers in their setts before badger hunt was prohibited), therefore, in this case the chance to be thoroughly blocked in the chamber decreases. An additional point is that the ground in a blocked way out may subside, so the chamber will be not closed tightly and badgers will not suffocate. We also guess that the raccoon dog’s possibility to block torpid badgers in their sleeping chambers depends strongly on the ground characteristics of the sett area. When the ground is sandy, it is easier to block, whereas in the conditions of hard clay grounds it is almost impossible for raccoon dogs to do this. Therefore, it might be safer for badgers to hibernate in setts on clay top-grounds.
Marking of badger setts
Marking interactions between badgers and raccoon dogs were evident at occupied setts. Raccoon dogs and badgers marked their setts by latrines to alert other individuals of badger and raccoon dog. Raccoon dog usually marked outside the burrows, while badgers marked both outside in the sett area and inside in a dead end not far from the entrance.
However, when the badger population density was low, we could not find a lot of signs of badger marking behaviour outside the sett. This is a real peculiarity of badger marking behavior in its low density population in Belarus, while in many other European countries badgers mark their settlements outside a lot. There is no doubt that it may be explained with the really low density in the declining population of badgers. Conversely, raccoon dogs marked badger setts a lot. During early spring surveys of badger setts, there were found latrines left by raccoon dogs at all setts (100%), where they overwintered (n = 238). There was one latrine in 120 cases (50.4%), two latrines in 63 cases (25.4%), three-five latrines in 55 cases (24.2%).
Thus, demonstration of marking interactions by marking setts with scats appears to be common, especially for raccoon dogs, who intensively mark badger setts on a regular basis.
Killing and aggressive interactions
Aggressive interactions between badgers and raccoon dogs were registered either directly from the hides or defined by tracks and during radiotracking. In early July in Barsuchykha locality in Haradok district there were found two badger cubs killed by racoon dogs just few hours before (identified over footprints, the distance between canine marks on the cubs, hair). Besides cubs there were only two badger individuals in that sett. It could happen that raccoon dogs killed the cubs, while adult badgers were absent for feeding. Within big badger family groups such incidents are less likely to happen, as someone from badgers are always present inside the sett or nearby. Conversely in case of small badger family groups probability of similar incidents increases. In the end of June of different year but near the same sett we found the fresh body of raccoon dog cub evidently killed by badger. A week later there were found another body of raccoon dog cub, markedly corrupted but with a lot of clear bite marks. We are inclined to evaluate these two kills as a successful aggression of the badger, who in such a way attempted to get rid of continuous presence of raccoon dogs in its residence.
As to badger aggression toward adult raccoon dog individuals, such attacks were observed not once directly nearby badger setts. However, raccoon dogs usually were quick enough to avoid those attacks. Moreover, such badger aggression toward raccoon dogs did not force raccoon dogs to leave the sett, so after a while they came back the same place. During observations form the hides, we registered totally 11 cases of badger aggression toward raccoon dogs within their settlements. On each occasion raccoon dogs managed to avoid those attacks and did not leave the setts (i.e. it was registered the next days, at least, or just after the badger’s attack). Also three respondents evidenced about similar incidents of badger aggression.
Such behavior may be explained by the following. It is clear that comfortable and protective badger setts attract raccoon dogs. However, an adult badger is evidently stronger than even a pair of raccoon dogs (as they usually live in couples). Therefore, the latter fail to chase badger away from the sett. At the same time, the thing that raccoon dogs realize badger aggressivity toward them is likely to make them practicing some interferential actions, first of all burying badgers during winter torpor.
Summarizing all above-mentioned evidences of badger – raccoon dog aggressive encounters, it should be noted that at badger setts aggression happens from both sides, but raccoon dogs being more quick are hardly attackable from strong but a bit clumsy badgers. Conversely, badgers are more vulnerable to raccoon dog aggressive attitude during the period of winter torpor because of the risk of being tightly blocked in their sleeping chambers by raccoon dogs.
Also in small badger family groups, cubs are at danger of being killed by raccoon dogs, when adult badgers leave their setts for feeding. At the same time, raccoon dogs do not use much badger setts for rearing pups. If they do, they keep their litter there just for the first 10-20 days and always with mother’s presence.
Thus, quite possible that it is certain aggressive counteractions of raccoon dog against badger that appear to be one of the essential reasons of badger population decline in Belarus.