Summer hunting versus winter hunting
We found a great difference in the hunting mode of lynxes between the warm and cold seasons.
In the cold season – particularly during periods of snow – lynxes hunt either by ambush from concealed ‘resting’ sites on the ground (often under spruce branches) or by patrolling prey rich habitats and stalking.
Stalking doesn’t mean lynxes are continuously on the move. When stalking in snowy conditions they often stop and sit or lie down on the snow to look around for prey; on good vantage points such as small elevations in the terrain, near forest edges, clear-cuts, in open forest or anywhere near prey concentrations (pathways or resting sites).
These ‘stalking – resting sites’ by lynx are usually in relatively short use (but not always, it can be for several hours). In fact many of the resting sites found during snow tracking of stalking lynxes might be better described as ‘watching sites’… Quite often many of these watching sites can be found in close proximity to each other, in places with good prey concentrations. During stalking they stop, look around and wait for a while, then walk a bit further and do the same again. From open watching points they can start to stalk prey when they see an opportunity.
The other hunting manner frequently used in winter is ambush hunting from concealed laying sites on the ground (often under low spruce branches). These concealed laying sites are used for a longer time, up to 24 hours or even for several days. If a lynx kills a prey, it will stay in the area to consume the prey and continue to hunt the same spot in the same manner. This way it can stay for 5-20 days in a small spot of 1-2 km in diameter. These days of hunting by ambush can be alternated by days of territorial marking when it goes faraway and then comes back afterwards.
In the warm season, lynxes mainly use a specific type of ambush hunting, namely waiting for prey from a hide on a height (specific inclined trees, root plates,..), 2,5 – 4 meters above prey pathways. Such waiting usually lasts about ten hours or more. In Paazierre Forest and Naliboki Forest we registered at least 18 cases where lynxes were hiding in trees, waiting for prey for quite long (4-32 hours). We call this ‘hide-watching’.
Lynxes also frequently use open watching points at a height (inclined trees etc.), where they scan the surrounding habitats. It can be for hours, but more often this type of watching lasts only 5-30 minutes. We call this ‘open watching’.
By waiting for prey from a hide above 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.). This summer hunting mode is also advantageous for another reason: mosquitoes! In the swampy forests of Belarus, huge swarms of mosquitoes are a real problem for lynxes. However, they are concentrated in the vegetation just above soil level. A few meters above the ground there are already hardly any mosquitoes.
This very specific summer hunting method explains why lynxes use only a very small portion of their home range intensively in the warm season: 7-11% versus 39-42% in winter. For further details and discussion on the relation between hunting and home range size, – structure and usage of housing spots we refer to the topic ‘Home range size, – structure and usage of housing spots’.
From early autumn on there are gradually fewer and fewer mosquitos, 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.
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!
Hunting for badgers
During the warm seasons of 2016 and 2017, we registered three cases of lynxes waiting at occupied badger setts. Two cases were registered by camera traps, the third was registered by inspecting tracks at the sett, and suggested it was waiting for about 4 hours: it was a rainy day and there was a dry spot where it was sitting. In all these three cases there were not many mosquitoes while the lynx was waiting.
In summer 2017, on an occasion with many mosquitoes, we recorded the reaction of a lynx at an active badger sett. We see the lynx inspecting and sniffing the sett, but the many mosquitoes (clearly visible on the video footage) seem to prevent it from waiting on the soil near the sett.