Hunting modes of lynxes in Belarus

Hunting from ambuscades is the most commonly used hunting mode of lynxes in Belarus. Ambuscades can be situated in sheltered sites on tree branches or inclined big trees, concealed sites under dense low spruce branches, etc. In the warm (snowless) season, lynxes mainly use arboreal ambuscades. Usually these are inclined trunks of trees (quite often spruces) fallen on other trees (mainly spruces). In winter, especially during snowy periods, lynxes more often use hidden sites on the forest floor, under dense and low spruce branches or at the edge of treefall or thickets. However, both types of ambuscades (at a height in trees or on the forest floor) may be used year-round. In the majority of cases, such an ambush hunt-watching point is situated at prey pathways or at the spots where prey forage rather often.

Another mode of hunting by lynxes involves watching for a short time from an open, elevated spot followed by stalking and a fast attack of the prey. However, this mode is used much less often than hunting from ambuscades. It is mainly applied during long walks, when the lynx is marking its terrain.

We found a great variety of ambuscades on both ground level and in trees. Those ambuscades at the ground level (the forest floor) are usually situated under dense, low branches of young spruce trees, but sometimes they are in a tuft of tall grass or dense bushes at the edge of an opening in the forest or at the edge of treefall within forest. Ground level ambuscades were used a lot in the mosquitoes-free period (mid-October till late April) and especially in the snowy period. They may be located at prey pathways (19%, n=103) or in spots where prey often forage (81%, n=103).

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Silver birch succesion forest in former felling area.  Such habitats are usually inhabited by roe deer. Under such a spruce (at the right on the picture) a lynx may be be in ambush  for a fairly long time (up to 24 hours).

In the warm season, particularly when there are plenty of mosquitoes, lynxes prefer to hunt-watch from trees. Amongst 54 known lynx ambuscades on trees, most of them (42 ambuscades or 78%) looked similarly: a tree trunk of various species (quite often spruce, 38%, n=42), which was inclined by wind and leaning on another tree. The tree that supported the inclined tree was mainly (93%, n=42) a big spruce with a dense crone. While hunt-watching, lynxes were always sitting or laying under this dense spruce crone, which offered them sufficient protection from rainfall. The height on which the lynxes were sitting was from 3 to 10 meters (usually 4 to 6) above ground level. On such a height there are hardly any mosquitoes. Lynx ambuscades on trees were mainly situated at prey pathways (91%, n=54). Sometimes lynxes used ambuscades on trees in winter as well, but mostly during snowless periods. They seem to dislike a lot of snow on their arboreal sitting place. Moreover, the use of arboreal ambuscades in winter strongly depends on the amount of concealment of the ambuscade in the absence of foliage. While inspecting the lynx home ranges with the aim of finding actual or potential ambuscades for hunt-watching by lynxes, we evidently noticed that there are not so many places with potentially effective ground-level ambuscades, whereas relevant arboreal ambuscades are really rare. Our experience from these inspections suggest that, taking the seasonal changes into account, only a quarter of forested habitats may be used for ground-level ambush hunting, whereas suitable arboreal ambuscades are present in less than 1% of the forest habitats. This explains why the spotted lynx home ranges (Chapter 4) are well connected with hunting from ambuscades as their most commonly used hunting mode. This also explains why in the warm (and sometimes rainy) mosquito season, lynxes seem to ‘disappear’ from the forest. In these circumstances it is very hard to find their tracks and register them with camera traps, if you do not know where their ambush hunting sites are located.

By waiting for prey from an ambuscade above or at their pathways, lynxes can exploit passing prey from a larger area. Indeed, in the warm season several prey species have multi-annual pathways, especially near seasonally abundant food sources (e.g. the first spring herbal cover in forest on rich soil; acorns from late August-November in oak stands; blueberry and other berries in pine stands in July-September; areas around leks of black grouse and capercaillie, where their nests and fledglings are located in May-August; etc.).

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Lynx in ambush for prey  on a inclined tree on top of a rootplate. Underneath the tree there is a pathway of ungulates.

Once in the ambuscade, the hunt-watching and resting by the lynx may continue for a relatively long time, up to several days. The longest time we registered a lynx staying in one point (hunt-watching site from an ambuscade in an inclined spruce) was 32 hours. Usually, lynxes stay for several hours in an ambuscade. Furthermore, the longest time we registered a lynx staying in one small house area with a few ambuscades was 20 days; that took place within 1.2 km2 around a carcass of red deer killed by the lynx. Presumably, there were other small kills of the lynx as well, like red squirrel and mountain hare, because we found the remains of those species in the fresh lynx scats, which we found at a lynx track not far from the red deer carcass. As to this case, one might argue that the reason for such a long stay (20 days) of this lynx in one small spot was guarding and consuming the big kill. However, both before and after the kill we frequently registered lynx tracks in that spot. At the same time, in many other similar places not far away, we did not register any lynx tracks at all. Thus, while a lynx kills a prey in its house area with several ambush sites, it consumes the kill and continues to hunt in the same place by the same manner. In effect, there may be several consequent kills by the lynx, as it stays mostly in the same spot for 5-20 days with only little walking in a small area of 1-2 km in diameter. Some of these days, the lynx may go faraway, mainly for territorial marking, and come back afterwards.

Roughly estimated, we may say that 90 % of the lynx hunting time in the warm season is occupied by hunt-watching from tree ambuscades, as lynxes almost stop active hunting (patrolling and stalking) when mosquitoes become numerous.

From early autumn on there are gradually fewer and fewer mosquitoes, and in some suitable places lynxes start to wait for prey on the ground. Moreover, when foliage disappears in late autumn lynxes are less concealed, which makes this a less efficient hunting tactic. With the return of snow cover, hunting from trees probably becomes even less efficient and also uncomfortable for lynxes, thus they gradually adopt their more ground based winter hunting mode. At the same time this seems to be an adaptation to seasonal changes in prey movements and availability of (vulnerable) prey. The more mobile winter hunting mode is also perfectly compatible with increased marking activities by lynx in winter and preparations for mating season. See ‘Home range size, – structure and usage of housing spots’ for a detailed explanatory hypothesis.

So, another hunting mode lynxes use in Belarus involves watching for a short time from an open, somehow elevated spot (trunk of inclined tree, big stump, mound or heap of various origins, etc.) in order to notice prey beforehand, stalk and then fastly attack them. Lynxes  mainly use this hunting mode mainly during long walks, which are basically motivated by territorial marking.

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Lynx looking around for prey: open hunt-watching
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Lynx looking around for prey: open hunt-watching
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Lynx  open hunt-watching site at  a canal bank, overviewing a marshy opening in the forest

 

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Lynx  open hunt-watching site on top of a pile of young birch stems

Sleeping or hunting? A world of difference…

The longest period we registered a lynx waiting for a prey from a hide was recorded in early winter: 32 hours.  No urination or defecation was found under this hide despite of the long waiting period. So, during winter lynxes use this hunting tactic as well, particularly if there is almost no snow on inclined or fallen trunks.

Bioenergetics studies have shown that the energetic expenditure of a raptor watching for prey is the same as when it is flying. Who knows how much energy it takes for a lynx to watch out for prey for so long…

High energetic cost should lead to high daily food intake. Investigating daily food intake of lynx by tracking requires a rigorous approach to avoid bias. Wolves tend to abandon their kill when it has been approached by humans. Lynxes, however, are not bothered by human presence near their kills. Taking into account all pitfalls (e.g. lynx prey eaten by scavengers), we recently estimated a daily food intake of 3.4 kg by lynxes, whereas in wolves under the same habitat conditions this was 1.8 kg and 2.7 kg under conditions of poor and rich prey supply respectively (Sidorovich 2011). The preliminary estimate of 3.4 kg daily food intake by lynx is derived after 1400 km of snow tracking lynxes, mainly between 1995-2007 (mostly 1998-2004). To be 100% sure of the duration (in hours) of the trails, only 11 lynx trails with known timing were retained to calculate daily food intake. These trails (8 trails of adult males and 3 trails of adult females with 2-3 kittens) had a duration of at least 12 hours and averaged 27 hours. So, it seems that, despite their smaller size lynxes have a higher daily food intake than wolves! Perhaps this connects with frequent watching and waiting for prey, when the pose, concentration and state of readiness to suddenly attack prey demands a lot of energetic expenditure. In telemetry data such ambush hunting with a lot of energy expenditure is surely registered as sleeping, a severe artefact which leads to the idea lynxes are relatively inactive predators which sleep or rest a lot!

 

 

 

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