Surprisingly social lynxes: new information gathered during the winter of 2018-2019

In an earlier post, we reported several records of surprisingly social behaviour in lynxes: males walking with females outside the mating season and subadults joining mothers with kittens. In the book “Unknown Eurasian lynx Lynx lynx: New findings on the species ecology and behaviour” by Vadim Sidorovich, Jan Gouwy and Irina Rotenko (2018) we described all the cases we registered until the winter of 2018-2019 and stated that the Eurasian lynx is clearly a more social carnivore than what is believed based on general views about solitary carnivores.

During the past winter of 2018-2019 we continued to gather information about sociality in lynxes by snowtracking and extensive camera-trapping with individual identification by fur spot pattern analysis in Naliboki Forest, north-western Belarus.

Before we report about the new information on such poorly known social contacts of the Eurasian lynx, obtained during the winter of 2018-2019 (after the publication of the book), we will first resume the cases described in the book.

Findings on sociality in lynxes published in the book:

We revealed features of cooperative living of adult males with females without kittens. Indeed, in the winter of 2016-2017 we found out that an adult male (Kazimir) and a female lynx (Hanna) were regularly walking together from November up to the mating season in February-March. We photographed them at the same spot in November within the same minute. In the next months by means of snowtracking, we found out that they regularly hunted and groomed together. At the same time, Kazimir tended to go alone for territorial marking far from the house area of about 7 km², where they stayed together. Finally, Kazimir and Hanna split in mid-April 2017, and Hanna gave birth sometime in mid-May in Kazimir’s winter house area. Interestingly, our observations indicate that the pair bond of Kazimir and Hanna was so tight, that during the mating season of 2017, Kazimir stayed merely with her, whereas during the mating season of the previous year (late February until mid-April  2016) Kazimir most likely mated with three different females.

The next winter of 2017-2018 Hanna and two of her kittens stayed in the same area (i.e. Kazimir’s house area) and its surroundings (the total area being smaller than 30 km²). Kazimir’s winter proceeded in a similar way as the previous one, only this time he stayed with another female (Kazimirykha). The pair bond of this pair was not so tight, and after staying together most of the time in September-December, we only sporadically registered them together from January onwards. The joint stay of Kazimir and Kazimirykha in September-December was registered manifold by both snowtracking and camera trapping. We have clear indications that Kazimir copulated with both Kazimirykha and Hanna in the mating season of 2018.

During the winter of 2016-2017 we found another adult male (Bazyl’) and female (Bazylikha) regularly walking together from mid-January until late April. During snowtracking, we found out that they regularly hunted and groomed together. In February, they even went on large territorial marking excursions together. Bazylikha gave birth somewhere around mid-May 2017 and afterwards she stayed with two kittens within Bazyl’s home range.

In the winter of 2017-2018 we registered the fourth case (again by camera trapping combined with snowtracking) where an adult male regularly stayed (walked, hunted, groomed, slept etc.) with a female in the period of November-February. One interesting anecdote concerning this pair is that of an observation by three participants of a wildlife trip, who spent a night in January on a watching platform in the forest. In the morning they saw two pairs of lynx eyes in the distance in their flashlights. By looking at the tracks in the sand in the morning, it became clear that the lynx pair passed right next to (under) the platform without being noticed.

These observations suggest that, if an adult male lynx has an adult female without kittens within its home range, it tends to join the female. These females may be mainly subadults or adults whose kittens died early.  This joint stay of an adult male with a female includes cooperative hunting, simultaneously consuming of kills, grooming and sleeping. This cooperative living may last months or at least the whole cold season. However, the long walks of adult males with a lot of territorial marking are mainly carried out alone. So, cooperative living of adult male and female lynxes mainly takes place in housing areas.

An important question is how often this type of social behaviour in lynxes take place. For the moment, our very preliminary estimates suggest that at least a quarter of adult males frequently stays with a female out of the mating season.

We also found interactions between subadults, their mother and the new kittens. In the beginning of the winter 2016-2017 we photographed an adult female (we call her Jadz’viha) with her two kittens of the biological year together with a subadult, which was her kitten of the previous biological year. Later that winter, during snowtracking sessions, we also found their joint tracks, but not all the time. Often the subadult was walking alone. It stayed the whole winter in a very small area (approximately 10-15 km²), within the larger home range of the mother.

Since late summer and autumn 2017, we regularly registered Jadz’viha hunting together with a subadult, during which she left her two kittens of the biological year in a sheltered place. By camera-trapping and snowtracking, we occasionally registered all four lynxes (the mother, her two kittens and one subadult) walking together in November-December 2017 and in January-February 2018. Already in the winter of 2015-2016, we registered Jadz’viha leaving her two kittens in treefall as she went hunting with one subadult.

Another mother lynx (Vieranika) was registered with two kittens in November-December 2017, while in January 2018 she was registered with three kittens for at least a week; perhaps two kittens of the biological year and one subadult. In Februari she was noticed again either with two or with three kittens.

Based on these findings, we think that some mother lynxes tend to accept some of their kittens of the previous biological year, if they are still roaming within their home ranges. As mentioned in the statement, this behavioural feature may lead to a higher survival in subadults,  which is demographically essential, because mainly these inexperienced subadults die from starvation, when optimal lynx prey (roe deer, hares and tetraonids) are scarce, as supported by four such registrations.

Concerning the frequency of such reacceptance of subadults by their mothers, we assume that a third of the mothers accept subadults, i.e. one or even two kittens of the previous year.

We also suggest a possible assistance of adult males for mothers with kittens. During our long-term zoological studies in Naliboki Forest and Paazierre Forest we started noticing that an adult male lynx often stayed nearby a mother lynx with kittens. Actually, in July-August we quite frequently found bigger lynx footprints close to markedly smaller tracks of a mother lynx and kittens. By inspecting these tracks, we found it very plausible that they were made simultaneously. Almost a third of such registrations suggested some relationship between the adult male and the family. In 2016-2018, while doing research on lynx denning behaviour and the raising of kittens, we came across seven more such cases. Three cases concerned early denning in May, four cases were related to the raising of small kittens in July-August.

In all three cases of early denning, an adult male was present in close proximity (hundreds of meters) of the denning site. We repeatedly registered this by controlling tracks and/or camera-trapping.  In at least two of the four cases, when small kittens were being raised, again an adult male was present in close proximity of the denning site. This was registered in the same way as mentioned above.

Still we may merely guess what was going on between the mother lynx with kittens and the adult male, on whose territory the family was staying. Perhaps the male was assisting the mother lynx by occasionally bringing food and protecting the family from possible wolf attacks, by preventing wolves from visiting the denning site?

In the book we stated that this last hypothesis as well as the other new findings on sociality in Eurasian lynxes of course demand further research. However, already it became evident that the Eurasian lynx is much more social than lynx researchers realized before.

New findings on sociality during the winter of 2018-2019:

During this winter, we succeeded to collect quite many facts of social contacts in Eurasian lynxes exclusive of between-mate relationships and mother-kittens behaviour. These facts were obtained by means of much snowtracking and intensive camera-trapping of lynxes in Naliboki Forest (about 60 camera traps were applied).

The main registrations were the following:

1) in mid-January, Kazimir (one of the known adult males) walked with an adult female having two kittens during three days, at least. All four lynxes were seen on the road as they walked together (just before they were seen they walked along the road for about 4 km), the next days, their fresh joint tracks (four lynxes, two bigger and two smaller) were registered for several times in the area.

2) in the beginning of February, one known adult female (Malanka) having two kittens was registered by camera trap with another non-relative lynx (subadult or adult). During the previous biological year Malanka had no litter, so that other lynx could not be her subadult. They stayed together for 7-10 days, at least. This lynx that joined her was very similar to the adult male which she mated in late February 2018, so, it’s possibly the father of the kittens. Remarkably, they were photographed in the same spot with treefall, where they mated before. Before the registered  fact of Malanka staying with this other lynx she was found in the area with kittens with kittens only for several times by both camera-trapping and snowtracking.

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The adult female Malanka on the upper photo and her two kittens with another lynx (central one; possibly the kittens’ father) on the lower photo. 

3) since late November, one known adult female (Pielahieja) without kittens stayed all the time with known adult male (Tsypruk). Their joint tracks were registered for several times and they were individually recognized by camera-traps. However, we failed to photograph them together, mainly because they frequently walked by the same pattern: parallel from each other on a distance of 10-30 meters. During the winter they mainly hunted actively (walking parallel, watching shortly and stalking) i.e. applied ambush hunting not so often compared to other lynxes.

4) one known adult female (Jadzviha) having three kittens joined with her subadult (her kitten of the previous litter, as we learned by camera-trapping) from time to time in November-February or with a big male (recognized by outstandingly big footprints). The three kittens were frequently left in a thicket and the mother hunted together with one of the mentioned lynxes. In mid-February one of Jadziha’s kitten has disappeared.

5) on the 30th of January, one known adult female (Maximiliana) having two kittens was scared from resting site at a clearcut edge, where they were together with an adult male.

6) one known adult female Ramualda having two kittens was registered with a subadult or even adult, but a fairly small one (we have no photos of her previous kittens). The two kittens were frequently left in a thicket and the mother hunted together with that other  lynx. In early February one of Ramualda’s kitten has disappeared.

7) One known adult female (Bazylika), had two kittens. During snowtracking sessions in January and February we found that the mother went hunting together with another lynx (most likely subadult as the tracks were of the same size as the mother) while she left her kittens (with much smaller footprints) in a thicket.

Thus, during the winter 2018-2019 we registered quite a lot of social contacts exclusive of between-mate relationships and mother-kittens behaviour. Staying together of adult female without kittens with adult male in non-mating season, adult male taking some part in the family life of a mother with kittens, as well as acceptance of subadults by their mothers already having new kittens –  appear common social behaviour of Eurasian lynxes.  These results of the winter 2018-2019 once more provide evidence that the Eurasian lynx is not a solitary species, but a surprisingly social species.

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