Co-author Irina Rotenko
One of the most important pressing questions of the Eurasian lynx behaviour and ecology is a role of an adult male in family life. It is well known that an adult male lynx accepts from one to three adult females in its home range. So, it may be up to three lynx mothers with kittens in the territory that is occupied by an adult male lynx. In our case in Naliboki Forest (central-western Belarus) there were usually two such families, rarer one or three families inside a territory of an adult male lynx.
In our study we found that lynx kittens of the year are quite good survivors (Sidorovich et al., 2018), for instance, compared to wolf pups. In Naliboki Forest, where we study on lynxes, a mother lynx having 2-4 kittens after denning in July then usually has 1-3 kittens in the late February-April. So, a mother lynx normally loose only one kitten during the first year of a litter. Wolf breeders loose around 60-90% of pups during the first year of their life in Naliboki Forest having mainly natural causes of pup deaths (killing by lynxes, trampling by cervids etc.). One of the reasons of good survival of lynx kittens of the year is seemingly their frequent staying on trees (basically inclined ones), where kittens are not available for enemies to kill. Nevertheless, it doesn’t look enough to provide so low mortality in lynx kittens.
Few years ago we guessed a possible significant role of an adult male (possible father) in raising of kittens that was totally unknown for the Eurasian lynx.
Since the late April 2020 till the beginning of March 2021 we traced three lynx family groups having 2, 2 and 3 kittens. In the cases of two lynx families adult male lynxes were tensely scratch-marking in denning areas. Mainly they made ground scratch marks. Also, in the cases of all three families traced by us adult males were registered a lot by our camera traps in the close proximity to the mothers with kittens. For several times we registered calling by the adult males as well as voice-to-voice communication between the mother and adult male at the distance not larger than 30 meters. In our registrations there were much support that, at least, in two of three these cases the adult males, which stayed around the families a lot, were fathers of the kittens. However, we haven’t documented those adult males altogether with the mother and kittens yet.
Anyway, for the moment according to out camera-trap registrations, we already got convinced that an adult male (possibly father), at least, protects a homesite of family by scratch marking, sound marking and just by his frequent presence nearby. Additionally, our registrations of lynx climbing tall trees for territorial calls in a family homesite were relatively often in particular since the late April till early July i.e. in the denning season of lynxes. Protecting of a family homesite by an adult male is quite great help to a mother. This is, at least, some role of an adult male (possible father) in raising of kittens.
Hypothetically we expected that kittens most of the time have to stay alone, while their mothers hunt. Actually, nowadays we obtained quite opposite results. Out of mating season in lynxes, there were surprisingly many registrations that mother lynxes stayed most of the time with kittens. That indirectly suggests that adult males might help mothers with getting food for their kittens.
To establish a research design for the question, we apply an idea that should be explained a bit. From our previous study on lynxes in Naliboki Forest (Sidorovich et al., 2018) we got to know that winter life of an adult male lynx consisted of prevailing stay in homesites with ambush hunting and consuming prey as well as regular its territory-wide walking-marking days. We know that prey, which were hunted by adult male lynxes in their homesites, were fully consumed by them. Quite the reverse, in the most of documented cases prey, which were hunted by adult male lynxes during walking-marking days, were eaten somewhat by them and left. However, adult males normally marked (mainly with urine) the surroundings (up to 100 meters away) of such a kill a lot. Respectively, we caught an idea that perhaps these kills were left by adult male lynxes for mothers with kittens to provide them with food, at least, partly. In this case stile of winter life of an adult male lynx is more complicated then above-stated and described in our recent book (Sidorovich et al., 2018).
To start checking all the above, during the winter 2020-2021 we decided to investigate this idea as much as possible for one model family with two kittens. The mother was called by us as Jurchykha. In the period from the mid-January till 20th of February there were found four roe deer carcasses that were recently killed by an adult big male lynx (we call Vikienta) within the homesite of Jurchykha. Two of the kills were fully hidden by Vikienta under broken reed and willow bushes and then covered by snow, but other two were left almost open (see photos below).
All four roe deer carcasses were eaten by Vikienta not much 2-3 kg and left without coming back to feed on them. At the same time after killing and eating, Vikienta marked the kills a lot in 4-12 points at the distance up to 120 meters around the carcass. The distance between the killed roe deer was around 300-1100 meters. This area was just a homesite of mother lynx (we call her as Jurchykha) with two kittens. The habitats consisted of downy birch swamped forest with canals and marshy openings (willow-reed thicket). That was former drained area that was abandoned by people. See the habitat on the photo below.
This swamped downy birch forest bordered with pine forest on sand dunes. Both habitat types were a lot used by Jurchykha with kittens and by Vikienta. Snowtracking and camera-trap registrations evidenced that both were in the close proximity from each other a lot of times.
Jurchykha was easily recognisable. She is slightly spotted having some distinctive spots, and you see her in 1st and 2nd photos below. One kitten was a female and has bigger spots (3rd photo below). Another kitten was a male, slightly spotted like the mother, but in the mid-winter he already was the same size or even thicker than his mother (4th photo below).
We would like to describe the story of consuming of each Vikienta’s roe deer kill in Jurchykha’s homesite separately.
Two roe deer were killed in the mid-January at the distance about 200 meters between. Both roe deer were killed at the edge of downy birch swamped forest and reed-willow thicket that were heavily covered by snow. Both kills were found by Jurchykha’s family soon and they were consumed during 7-10 days.
Here we would like to notice that tracing the lynxes we avoided to disturb them much to keep the situation natural. So, some of the values given are approximate.
It looked like the kittens hid all the time at the two carcasses in a complicated tunnel system under dense reed-willow jams that were covered by deep snow.
The snow was already hard and their tunnels were fairly solid as well as moving on snow cover was easy. The kittens continued staying in the tunnels even after they consumed the two roe deer carcasses entirely. Even the third carcass of roe deer, which was about 500 meters away, was visited by the kittens from the well-sheltered refuge in tunnel system under dense reed-willow jams . All this time from the mid-January till the early March kittens stayed in the area not larger than 2 square km. Jurchykha left them from time to time and walked around. In the late February she stayed with Vikienta for 3-5 days on the forested hills on the distance of 0.7-1.2 km from the kitten refuge. There were found three trampled spots that suggested possible mating of the couple in the last days of February. Then Jurchykha returned to her kittens.
It should be pointed out that about a third part of the two roe deer were also consumed by 3-7 ravens, red fox, pine marten and white-tailed eagle.
One of the roe deer (the forth one), which was killed by Vikienta quite far away from the kitten refuge, was not found by Jurchykha’s family. The kill was entirely consumed during two days by about 8 ravens, two white-tailed eagles, golden eagle, two raccoon dogs, two wolves and one red fox. Also, after killing of this roe deer Vikienta consumed 3-4 kg of the kill and was gone.
The third roe deer was killed about 500 meters from the described kitten refuge. See the kill signs on the video below. The kill was not hidden, but in three days it was totally covered by deep snow. Below see signs of the spot of kill.
Around 12-15 days the roe deer carcass was still hidden under snow. During this time Vikienta visited the kill once and again for five times, at least. Vikienta did not approach the roe deer carcass. Every time he came at the nearest distance of 7-30 meters walking along ice bound canals and marked the spot by urine for several times. We think that with such a urine-marking Vikienta indicated for Jurchykha where the food was and he tried to scare scavengers away from the roe deer carcass. Finally, Jurchykha with kittens found the roe deer carcass and consumed a half of the carcass. To regret our camera-trap lost energy with frosty weather and it registered just the family arrival to the roe deer carcass. In the video below you see Jurchykha and bigger male kitten. The rest of the carcass was eaten by two ravens, red fox, two pine marten and white-tailed eagle.
Thus, the above materials gained in relation to Vikienta adult male and Jurchykha mother with two kittens evidenced that an adult male lynx (possible father) takes at least some care in providing family, which stays in his home range, with food. Interestingly, what is about such a care for another mother with kittens that may stay in home range of a given adult male lynx. Concerning Vikienta during this winter, we documented that he regularly visited (at least, once per 5-11 days) the homesite of another mother (we call her Darota) with two kittens. Perhaps, he killed some roe deer for Darota’s kittens as well. Here it is worthwhile to notice that Darota’s and Jurchykha’s territories overlap considerably (for around a third part).
Of course, we traced only one case that suggested such a new phenomenon in the Eurasian lynx ecology and behaviour. It should be more materials collected on this important question. Nevertheless, we think that if it happened with Vikienta and Jurchykha’s family, it may be more or less common trait in Eurasian lynxes generally.