The common belief of the lynx-related zoologists is that parturition in lynxes takes place in a thicket somewhere under treefall. Sometimes, it really happens. However, during twenty years of searching for wolf dens in Paazierre Forest and Naliboki Forest in Belarus in April-June in 1997-2017 I have found more than one thousand of wolf dens (mostly without pups, former ones etc) under treefalls and other vegetation thickets (mainly young spruce ones), but only a few lynx denning sites (easily recognisable by presence of lynx hair) have been found under treefalls.
At the same time, when I worked in the regions, there were, at least, the same or a double number of lynx litters compared to the number of wolf litters. So, if female lynxes give birth under treefall and in thickets, I could discover markedly more lynx dens there, perhaps, hundreds of former lynx denning sites, too (i.e. similar as in the wolf case). Actually, it was not like that, because in Belarus female lynxes give birth and place early days kittens somewhere else, but not in treefalls or just vegetation thickets.
Also, it is easily understandable, why in Belarus mother lynxes avoid treefalls and other vegetation thickets as a possible place for parturitions and placing early days kittens. Lynx kits are vulnerable against mosquitos, much raining and predators’ attacks (wolf or red fox may kill them). Being almost open in treefalls and other vegetation thickets, lynx kittens may be a lot affected by all those factors. So, lynx kittens might have been somewhere else, if such possibilities exist.
Gradually during two decades I and during the last years together with Wild Naliboki team and Irina Rotenko from the Naust Eco station, we have already got many pieces of evidence ourselves that in Belarus parturition in lynxes and raising of early day kittens are going on in burrows such as former wolf burrows, abandoned badger setts and abandoned semi-destroyed beaver burrow network.
To support this presumption, we provide the following information in relation to denning of lynxes in Belarus:
- From 1997 until 2017: long stay (several weeks) of lynx kittens in abandoned badger setts was registered for eight times in late June-July by track inspection. Of course, we cannot rule out that the mothers brought the kittens into the setts after parturition, but we believe it is likely that they were born in the setts and started to appear at the entrances when they were a month old. Remarkably, in Russia, one of the three lynx dens that were discovered by lynx researchers in non-rocky regions was a lair with small kittens in an abandoned badger sett (Matyushkin and Vaisfeld, 2003).
- 7 May 2003: a recently used lynx den was found in a beaver burrow.
- July-August 2016: a lynx mother was photographed with her kittens at a comprehensive burrow network of a former beaver settlement on canals with sandy bank sides with a lot of footprints of the kittens that went into the burrows.
- May 2014: a female lynx equipped with a VHF-radiocollar gave birth in an abandoned peatery at the edge with dry forest. Despite inspection of the spot, the kittens were not seen, however, there were three possibilities where the kittens could have been: an abandoned badger sett with two entrances enlarged by wolves (the entrances were clearly used but no clear lynx tracks were found), quite wet beaver burrows and semi-collapsed wolf burrows in peat mounds.
- 14 May 2017: tracks of 2-3 weeks old kittens were found inside an abandoned beaver burrow, in a canal bank in spruce forest. Later in summer, the lynx family stayed in a spruce tree fall.
- May 2015: the raising of kittens at a former wolf burrow, registered by camera trapping. We are not sure if parturition took place inside the burrow.
- April 2016 and 2017: camera trapping revealed that pregnant female lynxes visited the same former wolf burrow as in 2015, but finally they did not use it, perhaps, because pregnant female wolves were interested in the burrow, as well. In early July 2017, a lynx mother stayed in this former wolf burrow with her kittens for at least a week.
- May-June 2017: a pregnant female was photographed by camera traps on the 13th of May. In late May or early June, the lynx family (mother with small kittens) stayed at a former wolf den (type ‘couch-den’), at the base of a fallen spruce, surrounded by a dense spruce thicket. On a distance of 60 meters, there was a wolf burrow that was visited by the lynx family as well.
- Early July 2017: a lynx family stayed in a self-made, shallow burrow in sandy soil, under a root plate of an uprooted tree on a clearcut with many tree remains and early reforestation.
It looks like, at least, until recently, when burrows, first of all badger setts, were a lot vacant (i.e. abandoned) in our main study area in Naliboki Forest because of the decline in badgers (Rotenko, Sidorovich, 2017), just burrows were seemingly the main denning sites of lynxes. The last years that has a lot changed in Naliboki Forest due to the recovering of the badger local population and the other important changes in the local vertebrate community (see another blog post on the question denning in lynxes). It may be also added that we had not enough time to find out how it was going on with lynx denning in Naliboki Forest, but already many changes seemingly happened there.
Nevertheless, we guess that even before not only burrows and sometimes treefalls were denning sites of lynxes in Belarus.
To learn something more concerning denning in lynxes in Belarus and to built effective hypotheses for ourselves on the topic, we questioned many people (hunters, wolf pup searchers etc.), let’s say to whom it may concern.
The rare information we learned from such respondents was very interesting:
- Once small kittens were discovered in inactive badger sett similarly as we suggest above. The kittens were still blind, and the entrance was enlarged by wolves several years ago.
- Twice respondents discovered lynx kittens under compressed logging remains, where kittens were well protected from all three negative factors mentioned above. According to their words, it looked like mother lynx did not go into the logging remains mound and just called the kittens to get outside, when it came to milk them or brought meat food.
- Twice lynx kittens were discovered on trees in the place, where one big spruce was fallen (inclined) on another big spruce. Kittens were at a height of 5-7 meters on a flat place that was somehow appeared from branches at the spruce trunks. In such a place again the lynx kittens were entirely protected from three negative factors.
- Also, one respondent found lynx kitten in an old treefall that was overgrown densely with spruce thicket. They were at root plate of an uprooted big spruce. Another finding was under many spruce branches compressed on each other in the place, where two big spruces were recently fallen by wind, and one crown laid on another one. In such a place lynx kittens were protected from raining and mosquitos, too. One former lynx den was seen in ledum shrub among bog with suppressed pines on a distance of about 200 meters from the bog edge. In such a boggy place there are usually a few mosquitos too because of too acid peat soil.
Also, in the book by Hepther and Sludskij (1972) authors mentioned one lynx den that was found in the central part of Belarus in the kind of a couch under a spruce with lowly located dense branches.
Generally, we think that both kinds of the above-described information in relation to denning in lynxes are biased for several reasons. Our one is biased because we did many studies on badges and were present at badger setts a lot of time. The messages that we received from respondents are biased because the findings were made with not a small dog, while they were walking in forest habitats, and if such a dog was baking on a burrow, normally the owner took the dog away. As to our part, we have never walked in forest with any dogs in the denning season.
Despite of the mentioned information biases we assume that until before the badger population has recovered and the species got a high population density, by occupying all present burrows (including former wolf ones, beaver burrow network in non-wet banksides of canals and red fox earths), just burrows were the main type of dens for lynx kittens of early days, at least.
Concerning the timing of giving birth by female lynxes in Belarus, it appears to be prolonged; parturition happens starting from the mid-April and perhaps until early June. Nevertheless, mainly births in lynxes mainly occur during the first and second decades of May.