The variety of life styles of Eurasian lynxes in Belarus: a combination of the gained results and hypotheses

In Eurasian lynxes there are several age-sex categories, which are strikingly or markedly differed by their life styles.  The data that leads us (Naust Eco Station & Wild Naliboki) to this conclusion originated from about 2300 km of snowtracking lynxes, multiannual study of lynxes with camera-traps (up to 70) and much other various research results. Among them the results of two lynx telemetry projects.

Before describing the revealed differences in the life style of the different sex-age categories in lynxes to be more backgrounded in the description, I anticipate that there is a need to list the main features of lynx home ranges in Belarus. Moreover, an occupation of territory by a lynx is tightly connected with its life style.

Home range sizes of indi­vidual lynxes in Belarus vary a lot. For this reason,  we did not calculate any averages or other statistics that has not much sense in such a variable situation. Home ranges of lynxes in Belarus  are always much smaller in subadults (10-43 km²) and, perhaps, in adult female without a litter (27 and 70 km²), whereas adult males may have very large home ranges – up to 203 km² (minimal 61 km²), and mothers with kittens have home ranges of intermediate size (34-89  km²). Lynx home ranges in the same sex-age category were getting larger with poor prey supply.

In a more or less dense population of Eurasian lynx individual home ranges overlap greatly. Even adult male home ranges overlapped a lot. If the population density is higher than 2 lynxes per 100 km², in non-mating season from 2 to 6 different adult males (mean about 4) may be registered at the majority of frequently used marking points within an adult male home range. Nevertheless, almost every adult male lynx has its own exclusive territory, where other adult males visited rarely, but an adult female with or without kittens as well as a subadult female may stay. Such an adult male exclusive territory is usually not large – approximately 10-30 km². This territory usually includes one or several house areas with potential favourable mating spots. Adult lynx males try to defend this small territory with several mating spots strictly from adult males.
If population density in a given forested terrain is about 3 lynxes per 100 km² and higher, there is no doubt that the whole terrain has already been shared between adult males. Up to 4 (normally 2) adult females may live in a particular home range of an adult male, and small territories of subadult lynxes may be everywhere. Here it is worthwhile to notice that due to a high overlap in adult male home ranges such females’ home ranges are placed in the home ranges of neighbouring adult males simultaneously.

The above variations in home range size of different lynx categories as well as home range inclusion are more or less similar as in the other published studies (overview in Herfindal et al., 2005).

Now the description of sex-age groups of Eurasian lynxes having distinctive and specific life style will be given.

The most outstanding   category of lynxes is a family group that normally consists of a mother and her kittens. After parturition, a mother lynx stays at the lair with small and vulnerable kittens, and she leaves them shortly for foraging only.  The gained materials already suggest that in the denning period and few months of post-denning life quite often an adult male that staying nearby, forages for the family, too. According to our data a mother lynx is absent at kittens about 6% of the time only. It looks like it is too short time for sufficient foraging, and a lynx family actually needs help of an adult male to get enough food.

Of course, a mother lynx forages, too. Mainly mother lynx hunt actively on small prey like grouses, red squirrel, mallard, young hairs or roe deer or even on voles, and perhaps she uses some ambush hunting as well, but greatly less than other lynx categories do.

Here it is important to clarify what we mean under ambush hunting, as we will frequently use this term in this text.  We define an ambush hunting in lynxes as  staying for fairly long in an ambuscade (more or less hidden site) and then stalking of detected prey over a short distance or les often directly jumping on a prey from an ambuscade.

But  we come back to the life style of mothers with kittens. In the busy denning period, ambush hunting by the mother perhaps lasts not longer than a few hours. When in the beginning of August kittens begin to move with enough speed and agility, mothers start to take the kittens with them to walk. Such walks are very important in the learning process of  the kittens, but at the same time it is dangerous for the family, as wolves that live in close proximity in the same habitats  may pose a threat for the kittens.  Therefore, mother lynxes with mobile kittens, anyway tries to hide them in a safe place with an easy possibility to climb a tree or get a burrow, and she supplies them with enough food. Sufficiently large treefall of several layers having some still standing trees and with a tunnel passages under the layers of fallen trees is perhaps optimal habitats for lynx kittens to stay. We have got enough  registrations that wolves do not venture to enter in such habitats, if they smell a lynx there.  When a mother lynx finds such a sheltered place and provides kittens with food soon, she tries to forage in the vicinity again and keeps her kittens there as long as possible.  Adult male lynx may help to the mother with getting food for kittens, too. So, such a lynx family life in a sheltered refuge may continue rather long – up to two months. But usually something unfavourable happens earlier, for instance, a disturbance by people or when the mother failed to get enough food around this spot where the family mainly stays. So, usually such a stay of kittens in a particular spot continues for 7-12 days only. By leaving the spot of recent stay mother lynx walks by searching for the vacant (from other lynxes) places with a relatively rich prey supply. She tries to catch prey, while moving with kittens, only dropping them behind for a short time (less than for an hour). When the mother caught something bigger like roe deer or beaver or the family got such a kill from an adult male, she tries to establish the former life style, i.e. leaving her kittens in a safe place with food, while the mother will continue hunting in the vicinity.  Quite often mother lynxes tend to accept one (or rarely even two) of their kittens of the previous biological year (i.e. subadults) that still stays in the mother home range. Concerning the frequency of such reacceptance of subadults by their mothers, for the moment we state that 30-50% of the mothers (from each third mother to a half of them) accept subadults for a significant time. Moreover, sometimes a mother with kittens may stay with an adult male for a few days (up to about 10 days).

It looks like such two lynxes (mother and subadult or mother and adult male) are markedly more successful to hunt. They mostly apply the hunting tactics of patrolling of habitats with rich prey supply and stalking. While patroling, they walk at parallel. While stalking, they stalk the same prey from opposite sides; as one lynx initiates the attack by jumping, another lynx waits to attack in some ambuscade on the possible escape route of the prey.

According to 662 photo and video registrations of lynx families in July-October behaviour of a mother lynx at kittens predominantly consisted of playing with kittens (44% of the time), watching around from a spot of kittens’ stay (15%), sleeping (19%) and grooming kittens (13%). Markedly often playing with kittens (44% versus 21%) and joint sleeping (19% versus 11%) were documented in July-October than in November-February. Interestingly, that mother lynxes were absent of the spots of kittens’ stay so little only: about 6% of the time in July-October and 16% in November-February.

In November-February, having about 620 km of snowtracking of mother lynx with kittens and 234 camera trap registrations of kittens, we preliminary reconstruct that in November-February a family stays in a safe place on average for 10-12 days (up to about 40-50 days). The average duration of walking between two such periods, when a family stays a sheltered place,  was 4-6 days (from 2 to 10 days) or in distance approximately it was  30-70 km.
Here it is worthwhile to notice that according to our materials, mother lynxes in heat usually do not send their kittens away to disperse before they go mating, but temporarily leave them in a safe place. After mating, most mothers reaccept their kittens for a joint life for at least a month longer. Being in heat, such a female mainly searches for an adult male by males’ scent marks, recent tracks and mating calls of adult males.

Adult male lynxes have a rather distinctive life style as well. From the information in several previous chapters it became already known the life style of this category quite well. To be brief, in the cold season adult male lynxes mainly stay in the surrounding of winter house areas (with well-sheltered mating spots), guard them, go for ambush hunting not faraway. This time, when adult males stay around winter house areas they hunt not only for themselves, but also to provide with food a family that stays often quite close on the distance up to 2 km only. Such neibouring stay of a family close to an adult male location was found in 49 out of 65 well-traced situations.

Approximately after 6-14 (on average 7-8) days staying in the house area with potential mating spots they undertake large walking-marking routes for 40-70 km with about 10 marks per one km. This marking itinerary usually covers the whole home range of the adult male and it takes one to 3 days to complete it. During these walking-marking days adult males only hunt either occasionally or deliberately around homesites of families to leave them food. Mainly such marking routes of adult male lynxes are very conservative: some parts of the route are totally the same each time they pass, other parts are the same for 70% at least. This inference about a conservative marking route is largely confirmed by both snowtracking and telemetry data as well as by camera-trap registrations.

Adult male lynxes emit territorial (or mating) calls from elevated position on the way of their marking walks as well as at the house areas with mating spots. It is also important to mention that for adult males to be successful in the mating season in late February-March, they need to have several thickets with tunnel-structures in their house areas, where mother lynxes in heat may safely leave their kittens and where she may agree to mate in safety not faraway. Such thickets we define as potential mating spots.

In the warm season, adult male lynxes spend a lot of time with ambush hunting, only  switching from one place of stay to another one from time to time. As to hunting from ambuscades of adult male lynxes, it does not mean that adult males jump on prey from an ambuscade. Watching from an ambuscade, they mainly fix the position of a prey and then stalk the prey, if it is already on a short distance. However, for the moment there are three registrations of a successful direct hunting jump of an adult male lynx from an ambuscade.

Also, in the warm season adult male lynxes spend much efforts to protect homesites of families, which stay in his home range. For that they marks family homesite intensively by scent marking and territorial calls. Also, they help with foraging for such families and bring kills in the close proximity to a family.
The next lynx category with distinctive life style consists of adult females without kittens. However, actually they have two different life styles, depending on whether they stay with an adult male or alone. Adult female lynxes living alone mainly forage by means of ambush hunting, and just this category of lynxes applies ambush hunting the most often, and they stay in an ambuscade the longest.  In this feature they are similar to adult males, but in comparison with them they do not mark so much and do not undertake long walking-marking routes. They gradually relocate within their home ranges, slightly marking on the way (about one mark per 0.4-2 km), and then they stop in a suitable place for ambush hunting for several days again.  Hunting on the way with stalking of a prey happens sometimes in this lynx category, but markedly less often than in the case of mothers with kittens. Adult females without kittens are the most passive category of lynxes: they do not mark and do not walk a lot and they mainly hunt from ambuscades. Such a life style is characteristic for adult females without kittens almost year-round, except during the mating season.

As to a joint life of female (adult or subadult) and adult male in non-mating season, such a 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 the whole cold season. However, adult males’ long walks with a lot of territorial marking are mainly carried out alone. So, cooperative living of adult male and female lynxes mainly takes place in house areas. For hunting such a couple applies two hunting modes. The first one again it is an ambush hunting. The second one is a patroling of prey-rich habitats walking at parallel to each other.

Sometimes such cooperative living of adult males and females is markedly different. Twice we traced a couple, which walked everywhere together almost the whole winter (since November till the mid-March in one case and December-March in another case) even on the very long walking-marking itinerary of the males (as far as we learned about 72 and 63 km, respectively). During these walks, it looked like the males marked normally (about 10 marks per  one km), but the females marked rarely. These two couples hunted a lot actively by patrolling prey-rich habitats and stalking prey cooperatively. When they were at the house areas, they applied ambush hunting, too.

Subadults is the last distinctive categories of lynxes. Again, perhaps, there are a lot of differences in the life of subadults that follow the mother, and subadults that are acting alone. Subadults that follow the mother have the same life style as the mother. Such a subadult frequently takes part in  active hunting of the mother i.e. patrolling and stalking. Lonely living subadults try different manners to hunt, including both ambush hunting and active hunting.
So, Eurasian lynxes of different sex-age-related categories have rather different life styles. It is evident that this behavioural variety is directed on successful breeding and higher survival.

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