I got interested in the Lynx project last summer, due to a farmers discussion (http://www.fwi.co.uk/livestock/finnish-farmer-delivers-stark-warning-lynx.htm) , and did a lot of reading about Lynx in Europe and the proposal to reintroduce them here. A lot of farmers are very worried about this, and some of the spokesmen for the Lynx project were being rather unsympathetic and harming their own case. I have tried to find how worried farmers should be, and whether the Lynx project can fulfil its own aims. Unfortunately family illness took my mind off this project and it never got properly finished, but I hope that the following might be helpful. I will try to improve this as soon as possible, but if I don’t start now, I will never get anything done!
The Lynx Project: What is it for? Purpose of reintroduction
It is difficult to work out why the Lynx Trust want to reintroduce Lynx, apart from some idea of justice to a species that has been extinct in the UK for 1,600 years. The nearest thing that I can find to a “Mission statement” from the Lynx Trust is the following: –
“The Lynx UK Trust is made up of a group of expert feline conservationists with specialisations in areas such as wildlife reintroductions, field research, ecology, biology and genetics, determined to return a sustainable population to the UK over the next decade.
We are currently engaged in a range of research to identify potential release sites and carrying out stakeholder and public consultations on the reintroduction of these cats to the UK. “
So perhaps their motive for a reintroduction is simply that they want to.
There is no doubting their very considerable expertise in protecting endangered species in this country and internationally. They are certainly experts in studying and working with animals. For part of my career I worked as an ecologist, and can sympathise and even share their obvious enthusiasm for Lynx and for the possibility of reintroducing long extinct species. However, I have some reservations about the way that they are going about this project, and about the claimed advantages of reintroducing the Lynx.
European Union Habitat Directive
The Lynx Trust say: –
“Under the EU Habitat Directive, UK Government is obliged to study the desirability of reintroducing select species to their former range which are threatened in Europe but have become extinct in the UK, if this is likely to contribute to their conservation. The Eurasian Lynx,
Lynx lynx, is one such species”
But in my researches, I have seen no evidence that the Lynx is endangered in other EU countries. Indeed, most research includes official figures on Lynx shot by hunters. If Lynx were endangered in these countries I would expect that data might include reports of hunters imprisoned.
In their opinion research, they divided people into proactive respondents, those who actively seek out and fill in forms, and passive respondents, about 1000 people contacted by a sub contracted polling company. The results show huge levels of support for Lynx reintroductions. The majority in favour, far exceeds any similar poll that I have seen, which makes me wonder who might have responded, and whether those organising the poll had selected their audience fairly.
Most people who might be affected by lynx reintroductions, might be local farmers, but 50 % of those in the active survey described themselves in urban categories, while only 10 % were in the most rural category. Only 3.8% describes their “interest” as farming, land management or forestry.
The survey was carried out in March, when many of the farmers most likely to be affected by the presence of Lynx would have been working around the clock supervising lambing or calving. While members of the farming organisations listed were only about 55% against the project, it seems likely that many must have been arable farmers, or land owners who pay others to look after livestock for them.
Claim that Lynx will reduce numbers of Roe Deer
Deer in general seem to have fairly good density dependent population control mechanisms. Red deer in the Red Deer Project in the Scottish Isles regulate their population so that it stays within the ability of the environment to support it. According to Polish research Red Deer populations fluctuate on a 7-year cycle just below the biggest population that the environment can support. On the other hand, Roe deer regulate their population a little bit nearer the maximum possible population, but the Polish researchers found that Roe Deer populations fluctuate at around a 4-year cycle, suggesting finer control at a level that is a little bit nearer the overpopulation level. The means of controlling population include the age at which females first produce young, numbers of young born, and death of older animals etc. As measurable damage is occurring to the plants on which Roe deer feed, one must assume that the Roe deer in Kielder forest are near their optimum level. If that is true, any loss in numbers due to predation will be compensated for by a relaxation of the population controlling activity. The birth rate will increase, and older animals might live longer.
Roe deer probably regulate their population at a higher level than Red deer because while Red Deer are big enough to be able to stand greater exposure outside the forest and eat mainly long lived perennial plants like grass and heather on the moors or shoots on trees that they can reach, Roe deer with their small size are specialists at eating low growing shrubby plants strictly within the shelter of trees – or at least hedges. Species like bramble or elder can be eaten down to the ground at the end of one year, and grow back to the same height in the next year. If we present them with fresh young saplings of other species the deer expect those saplings to behave in the same way as bramble and elder. (Or seedlings or suckers of hardwood trees. Oak seedlings on the Park Grass experiment at Rothamsted Experimental Station have produced 2 leaves every year since the experiment began in 1843, but been cut down when the rest of the plot was cut for hay. Scientists have dug out a few of these seedlings and counted the tree rings at the base of the stem to prove that his longevity of seedlings is more than just a theory,) Eating things down to the ground is a good way of regenerating the food that Roe deer eat, if there is still enough light for regrowth the next year. Old brambles and shrubs would smother the regrowth, and are themselves, much lower yielding and less palatable then young growth. Brambles and Elder can get too high for Roe deer to reach, if left to grow. So in regulating their population to such a high level, relative to their apparent food supply, you could say that Roe deer are the farmers to the Red deer’s hunter gathering lifestyle.
Roe deer are considered a problem in Kielder forest because when they eat the growing tips of coniferous trees they kill the tree. As more hardwoods are planted this will be less of a problem because hardwoods grow from the base, and as the Rothamsted example, above shows, can survive an almost unlimited amount of pruning. And an oak sapling may only need to be missed by the deer for a couple of years before it starts to put on woody growth that is less attractive to the deer, and which will give the sapling a head start for the next year. A sapling growing up a protector tube will be almost as high as a Roe deer can reach by the time it gets to the top of the tube.
Roe deer are creatures of thickets, understory vegetation, and young trees. Kielder Forest, is relatively young woodland being open moorland just over 100 years ago. It has been managed as a commercial softwood plantation with a relatively short rotation, with nursery stock growing for a decade, before thinning and then growing for a couple of decades before being clear felled so that the process could start again. While one part of the forest was growing, another was being felled and another being planted with nursery stock. The young trees form what roe deer would see as a thicket, and areas that had been clear felled would soon be covered with brambles, providing the roe deer with additional patches of food before being planted. The thicket of new trees would remain attractive to Roe deer at least until smaller trees were thinned out. This method of management is ideal for Roe deer.
Recently management has changed to produce a longer rotation with hardwood trees in the nursery stock, and with plans to create a more natural forest by felling taller tree on their own, letting light down to ground level to encourage new shrubby growth, again ideal for Roe deer.
Under the old clear-felling system, Roe deer could be kept out of nursery areas by fencing, by patrols or other means of creating disturbance. Under the new management system this sort of control is made much harder. However, as the trees grow, and there are shaded areas devoid of shrubby growth between areas of light and shrubs, deer will have to keep moving from one small shrubby area to another. They will feel exposed on these frequent short journeys, and this offers an opportunity for management. Choosing trees to fell that avoid giving the deer too easy a route between thickets will help, and perhaps arranging various types of scarers between thickets, and moving them around so that deer do not get used to them will help. This work is never easy, and I am reminded of a high-tech bird scarer we used to use. It imitated the distress call of a troublesome species, and the leaflet with it boasted of how one man had kept a pest species off 2000 acres of seedling crops single handed. As we read through the leaflet we realised that he was working full time, and the unit was bolted onto his car. As he drove around the estate, he stopped whenever he saw a flock of birds, switched on the scarer, threw a hand grenade into the middle of the flock, and then shot any birds that did not fly off, or which returned…..or which were already dead?
Keeping pests off a crop is never easy, or cheap, and I can understand the Kielder Forest Authorities wanting some help with this task
Lynx, on average eat 60 deer a year, so 6 Lynx might eat 360 roe deer a year. But with a population of 6,500 deer it would take 18 years for them to eat all the existing deer, even if no new deer were born. But potentially 6,500 roe deer could produce 10,833 fauns a year (assuming 5 fertile does to each buck.) That being the case the hope that the population of roe deer could be reduced very much seems very far-fetched.
Within the 250 sq miles of Kielder forest there would be room for, say 10 male Lynx territories. Assuming that each male mates with two females and they each rear 3 kittens to maturity, then the number of lynx in the wood would rise to about 90 Lynx, which could eat 5,400 roe deer in a year. This is still well below the reproduction rate of the deer. But of the 60 kittens reared to maturity, each year, perhaps half would have to find new territories of their own, and as all the potential territories in the forest would be occupied, they will all have to set up new territories outside the forest. That is unless they are killed by fights over territory, or disease. Though territorial fighting and disease do not appear to be major factors in population control as described in the literature. Indeed the large size of the territories appears to be an adaption towards avoiding aggression and disease spread.
Of course, these surplus kittens could be culled, but that does not fit in well with the Lynx Trust’s hope that the presence of Lynx will increase tourism in the area. Tourists are quite likely to mount campaigns to prevent culls, especially as the chances of seeing wild lynx seem so slight. For tourists to see Lynx there would have to be feeding areas, presumably baited with meet from human culled roe deer. This would be the Lynx’s natural food and may reinforce the hunting instinct of young cats. However, there would be a temptation to feed cheaper butchers offal, especially when weather made hunting roe deer difficult. Hotels and tourist attractions away from official feeding areas may also be tempted to set up their own illegal feeding sites, nd being unregulated may opt for cheaper butcher’s meat as well. The feeding of meat from farm animals in either scenario would train Lynx to attack farm animals, just as we have seen with urban foxes. (Whereas wild foxes feed almost entirely on worms, beetles, small rodents, and carrion, I have seen an urban foxes fed on kitchen scraps and butchers scraps attempting to kill an adult ewe, perhaps ten times the foxes weight Though the fox only succeeded in grazing the ewe, she was very traumatised and required 3 days of care away from the rest of her flock, which is itself a very unpleasant experience for a sheep.
While the adults released at the start of the project will have radio collars, and will be easy to track, the kittens may not carry collars, and will be capable of roaming over vast areas. Finding Lynx in the wild can be difficult as the story of Lilleth the Lynx that escaped from Borth zoo in 2017 has demonstrated. When Lilleth escaped, the owners and public knew where she had escaped from, and as a zoo bred animal she was not used to fending for herself and was seen near the zoo very soon after her escape. In spite of this it took several days before she was shot. A wild born Lynx will be a very different prospect, being used to hunting from cover and travelling long distances every day. A kitten, nearing maturity, will be driven by the need to establish a territory, and may travel away from their birth territory, covering many miles in the same direction every day, until they find a suitable unoccupied territory or some natural barrier that makes them change direction.
Lynx and sheep
The biggest numbers of Lynx attacks on sheep happens in Norway, where an old breed of Forest sheep (similar in habit, but smaller than the rare British Whitefaced Woodland breed), graze within the forest. In other countries lynx attacks are rarer, though happen throughout Europe from Greece to Spain. Studies have been carried out, particularly in Norway, Poland, Switzerland and France. Lynx’s normal target is young Roe Deer, of about 15kg, which it hunts in woodland, by ambush from thickets of bramble or similar small shrubby plants on which the Deer are feeding. Young sheep are vulnerable in similar situations, and within about 200metres outside edge of woodland. However, Lynx have been known to travel along hedges between more suitable areas of woodland, and also to hunt smaller animals like rabbits from cover within hedges. So, where Lynx become so numerous, that they have to accept lower quality territories, there is a danger that young sheep would be vulnerable within 200 metres of a thick hedge that links small areas of woodland. However, Lynx have a very strong preference for roe deer, and will not attack sheep if there are Roe in the area. There is some evidence that fully fleeced adult sheep are not in danger from Lynx, as Lynx are not equipped to penetrate thick wool
As Lynx prefer their prey to weigh about 15kg, sheep are most vulnerable from birth to shortly after weaning, meaning from January until mid-summer.
There have been cases of “rogue animals”, usually larger male Lynx in the mating season, when they are extremely territorial, killing up to half a dozen smaller adult sheep at a time, and nursing females taking sheep of any size that the individual can manage to kill, if the population of roe deer collapses for any reason. In these cases, the recommendation is that rogue Lynxes should be shot immediately, because these uncharacteristic killings suggest a change in the environment that has forced the nursing animals to return to the site of a successful hunt. (Though its should be said that Lynx do not normally return to the site of a hunt for many weeks)
So, most of the time, adult sheep are safe from Lynx, and the periods when immature sheep are at risk are well known, and there is a certain amount of knowledge about how to protect them. (Such as choice of grazing area, suitable companion animals, guard dogs etc). However, there is little practical knowledge in this country, with its relative lack of woodland compared with the rest of Europe. Historically it was believed that Lynx became extinct in Britain at about the time that the Romans left in about 450 AD. However recently the Lynx Trust has made a case for Lynx having survived here until the middle ages, which is convenient for them as the EU scheme suggests reintroducing animals that became extinct up to 1000 years ago. However, the middle ages, was a time of great expansion in the woollen trade, and it could be argued that Lynx were exterminated then because of the they threat they posed to sheep. Of course, the evidence, either way, is pretty shaky. For example, you could argue that Lynx died out because of habitat destruction, when forest was cleared to make way for sheep. All we can really say is that habitat suitable for sheep is not suitable for Lynx, which brings us back to the point that when lynx have to share land with sheep, sheep are vulnerable, if Roe deer (who prefer woodland to fields).
I would guess that when Lynx are introduced in particular forests, sheep will be safe, until all the potential territories in that forest have been occupied by a Lynx. Under the scheme proposed for Kielder that would be at least 8 years (assuming maximum birth rates and survival of Lynx kittens, and no dramatic changes in the Roe Deer population apart from that caused by the Lynx. (Though changes to the planting regime in favour of mixed woodland may result in a gradual lowering of the deer population, but probably on a much longer time scale.) While lynx numbers are building up in the forest there will be a few surplus (unmated) Lynx moving out of the forest, but they will tend to move long distances to find suitable habitat where there are many roe deer. They (males and females) will try to hold that territory until a suitable mate arrives, after which the population of Lynx in that forest will build up as it will in Kielder. Once all the territories in Kielder or secondary woodlands have been filled, new kittens that can find a mate before being expelled from occupied territories will try to set up territories overlapping forest edge and surrounding farmland, and the local danger to sheep may increase. In secondary woodland, in which individual areas are smaller than Kielder all potential territories will be filled faster than Kielder. Because there will be fewer of them in smaller forests, so the danger to sheep will rise much quicker. However, it is important to remember that the danger only normally exists within 200m of Lynx habitat or thick hedges that can give a lynx cover for a short ambush attack.
What farmers can do to protect sheep from Lynx
One of the things that farmers must care about, apart from the general welfare of their sheep, is developing strategies to protect sheep from Lynx if they are released into the wild in this country.
Campaign targets to reduce potential damage.
- Limit number of lynx released
- Ensure that all individual animals introduced into the UK, and all their offspring carry radio collars, that allow them to be continually tracked.
- Set up a compulsory and continuous permanent monitoring system, so that in 50 years’ time there will be a continuous record of the exact position (within 50m) of every Lynx in the UK for the whole 50 years.
- Fence the lynx into any area in which it is released. So, in Kielder forest, for example the whole area of the forest should be surrounded by a lynx proof fence, with all entrances and exits monitored to such a degree that lynx can never escape from the forest.
- Cull all lynx that are surplus to the numbers required to hold territories within the release area (for example Kielder forest.)
- If territories become unsustainable due to habitat change, disease etc, or if numbers of roe deer fall, then the number of lynx living in the release area should be reduced appropriately.
Assuming an irresponsible release of Lynx (that does not comply with the above campaign targets), then farmers may have to consider the following: –
- Ensuring that no sheep have access to forested or scrubby areas, especially at times when the Lynx are mating (when male lynx may be a threat), or when young kittens are being fed (when female lynx may be a threat.)
- Consider keeping larger breeds of sheep, where the breed is hardy enough to withstand the climate on the farm.
- Consider other uses for fields, all of which, or part of which, are within 200m of woodland edge. On lowland farms this may be using vulnerable fields for conservation – hay or silage making, or even for arable crops. On hill land consider grazing cattle on these fields, as even young calves are, in theory too big for lynx to kill
- Cattle health will have to be monitored carefully as small weak animals may become targets for aggressive male Lynx in the mating season, and may suffer trauma if not actual injury from being chased around
- If vulnerable animals have to graze near woodland edges in a difficult season, consider electrified fencing, which has proved to be semi effective in against the American lynx. (But be careful and take advice, as the small amount of literature that I have seen suggests that the American fencing is very different from that used in this country and may be a danger to humans.) The Americans seem to backup the fencing with war fighting weaponry!
- Where thick hedges form a link between areas of woodland, consider placing lynx proof barriers across the hedges that force the lynx into the open, and make the hedge a less attractive route.
- Control rabbit populations in hedges that link areas of woodland with thriving Roe Deer populations and in fields where sheep graze, as Lynx will hunt rabbits when young, or if Roe Deer are scarce. (Take advice on whether the presence of rabbits may help protect small lambs by providing an alternative food supply. This may apply on farms where lynx are present, but habitat will not support large populations of Roe Deer)
- Keep lambs indoors, or away from areas where they may be vulnerable to attacks from Lynx until the lambs weigh at least 15kg.
- Keeping guard dogs, ponies, cattle, or animals like llamas are claimed to be effective deterrents to predators in some places. However, other animals in fields with sheep usually cause the sheep some stress (and may transmit parasites etc) , and this can be damaging unless very carefully managed. While there are many enthusiasts for this practice (usually with guard animals to sell) I would be very careful before going down this route. Monitor someone else who says that this is a successful technique, for at least a year before you make a decision. Are the sheep their top priority, or the animals they hope to sell to you?
All these actions to protect lambs from Lynx, will have a cost, that will vary considerably from farm to farm. If particular methods prove effective on many farms, then the cost of equipment may be reduced over time, but as most suggestions above involve management rather than equipment, the costs may increase with wages paid to do the job. Experience with bird scarers on arable crops suggests that even the most expensive equipment only works well if it is constantly moved or swapped with other methods, to ensure that the pest species do not get used to it. Effective use of elaborate scaring equipment takes a lot of labour and is expensive.
Shooting Lynx on sheep farms is likely to be ineffective, as the territories of lynx are so big, and lynx may return to any particular point fairly infrequently. In Europe, there are people for who Lynx shooting is a hobby, or even perhaps a minor business, and farmers would perhaps have more success in working with “professional” hunters than hanging around at dawn and dusk for half the year before they even see a lynx, which may be a very small and distant target. Indeed even hunters may prefer to do their shooting in woodland where (with their skills) there may be a greater chance of finding a Lynx, but in the woodland they may be in conflict – or even a danger to – people working with the lynx. Trapping has also been used in surveys and to a lesser extent to capture known problem Lynx, but again my involve a long period of checking several traps 2 or 3 times a day.
Because of the variability of costs on individual farms, it might be a good idea for groups of farmers to calculate costs of their favoured method of protection on their own individual farms, before arriving at an average cost for a particular Parish, say. This may be used as an argument in campaigns or for grant funding etc.
References and notes
Extract from IUCN red List
The Eurasian Lynx occurs in a wide variety of environmental and climatic conditions (Schmidt et al. 2011). Throughout Europe and Siberia, it is primarily associated with forested areas which have good ungulate populations and which provide enough cover fur hunting. It inhabits extended, Temperate and Boreal forests from the Atlantic in Western Europe to the Pacific coast in the Russian Far East (Breitenmoser and Breitenmoser-Würsten 2008, Schmidt et al. 2013).
In Europe it can be found in Mediterranean forests up to the transition zone of taiga to tundra and lives from sea level up to the tree line (Breitenmoser and Breitenmoser-Würsten 2008).
In Central Asia, Lynx occur in more open, thinly wooded areas and steppe habitats. The species probably occurs throughout the northern slopes of the Himalayas, and has been reported both from thick scrub woodland and barren, rocky areas above the tree line (Nowell and Jackson 1996, Matyushkin and Vaisfeld 2003, Breitenmoser and Breitenmoser-Würsten 2008). Lynx occur sporadically throughout the Tibetan plateau, and are found throughout the rocky hills and mountains of the Central Asian desert regions (Nowell and Jackson 1996). In Armenia Lynx are strongly associated with true forests and arid sparse forests and to a lesser extent with subalpine meadows. Lynx have been observed up to 5,500 m (Guggisberg 1975).
The Eurasian Lynx is the largest lynx, and the only one to primarily take ungulate prey, although they rely on smaller species where ungulates are less abundant. Lynx kill ungulates ranging in size from the 15 kg musk deer to 220 kg adult male red deer, but show a preference for the smaller ungulate species, such as Roe Deer, Chamois, Reindeer and Musk Deer. Occasionally, Lynx also hunt foxes, hares, marmots, wild pigs, beavers, birds or domestic animals such as sheep and goats, or, in Scandinavia, semi-domestic reindeer. In European Russia and western Siberia, where Roe Deer are absent,Mmountain Hares and tetraonids form the basic prey base. Hares and birds are important prey also in other Central Asian regions where habitats are dryer and less forested (Breitenmoser and Breitenmoser-Würsten 2008, Matyushkin and Vaisfeld 2003).
Home range size varies widely from 100 to over 1,000 km² (Breitenmoser and Breitenmoser-Würsten 2008). Home ranges averaged 248 km² for males (n = 5) and 133 km² for females (n = 5) in a radio telemetry study in Poland’s Bialowieza forest (Schmidt et al. 1997). Average home range sizes in Switzerland were 90 km² for females and 150 km² for male Lynx. Male home ranges generally enclose 1-2 female territories (Breitenmoser and Breitenmoser-Würsten 2008). Densities are typically 1-3 adults per 100 km², although higher densities of up to 5/100 km² have been reported from Eastern Europe and parts of Russia and lower densities of 0.3/100 km² from Scandinavia (Jedrzejewski et al. 1996, Schmidt et al. 2011, Sunde et al. 2000). In the Saihanwula nature reserve in Inner Mongolia the density was estimated at 1.7-2.1/100 km² by camera trapping and track survey (Bao et al. 2014). In Turkey, a density of 4.2/100 km² has been estimated for the Ciglikara Nature Reserve, Antalya. However, this high Lynx density may be temporarily and may decline with major prey (hare) fluctuation (Avgan et al. 2014).
Kielder Forest occupies 250 sq miles (http://www.visitkielder.com/ )
In 1970 the population of Roe deer in Kielder forest was estimated to be about 6500 animals and increasing. http://www.nhsn.ncl.ac.uk/interests/mammals/mammals-north-east/roe-deer/
Comparison of methods for analysing diets of carnivores http://www.biosbcc.net/bio130/readings/ScatAnalysis_ComparisonMethods.pdf
The lynx is a pure carnivore and hunts smaller cloven-hooved animals such as deer, chamois, reindeer and musk deer. A stalk-and-ambush hunter he usually hunts in the evening when the prey is also active. If a surprise attack fails the lynx does not follow the prey. In attack, it leaps onto the prey sinking the claws of its fore-paws into its flesh and kills it with one bite at the throat. If it has killed a deer or chamois and is not disturbed it will come back on several nights until it has completely devoured the prey. Only the large bones, the head, the pelt and the innards remain. A lynx needs to kill one deer or a chamois a week, which means around 60 animals a year. https://www.euronatur.org/en/what-we-do/endangered-species/lynx/fact-sheet-lynx/?gclid=Cj0KCQjwub7NBRDJARIsAP7wlT8ThjAp7an6pXK0iqhnSidwdO_OBskz1TBAfZfpugM33XRHFG-JmkwaAnRSEALw_wcB
Typically crepuscular, lynx are active at dawn and dusk often sleeping out day and night in dense thickets and other safe hiding places; they are good climbers and will use trees and high rocks as places to lay up, watch for prey and even launch ambush hunts from. As with most cats they are solitary except for breeding season, however males and females overlap territories and carry out some form of communication through scent marks left around their borders. Territories vary hugely depending on density of prey species, some territories are just 20km2, some are over 400km2. Lynx make an unusual range of vocalisations through breeding season; growls, coughs, grunts and meow-like caterwauling, the rest of the time they are very quiet but will mew, hiss, growl, purr and chatter at out of reach prey just as pet cats do.
Life cycle and Reproduction
Breeding season focuses on February/March when females come into oestrous for about a week, this is typical of cold weather cats which have their young just in time for spring/summer so they can grow strong before winter. Eurasian lynx will not breed at any other time of year, though occasionally females who lose a litter will attempt a second in April. Through scent marks and vocalisations females will broadcast their availability for breeding to males in neighbouring territories who will then seek them out. Pregnant females find a secluded den and line it with feathers, fur and grasses for warmth and comfort, usually having 2-3 kittens after a 2-month gestation period. Kittens are born blind and helpless, but by 6 weeks are eating solid food and ready to leave the den. They are fully weaned by 6 months and become independent around 10 months, usually breeding for the first time at 2-3 years of age. Eurasian lynx can live to over 20 in captivity, but usually just to their teens in the wild.
Causes of mortality in reintroduced Eurasian lynx in Switzerland.
Seventy-two lynx, found dead in the Swiss Alps and the Jura Mountains (Switzerland) from 1987-99, were evaluated to determine the cause of death. Seventy-two per cent (52/72) of all animals died because of noninfectious diseases or causes such as vehicular collision and poaching. Eighteen percent (13/72) died from infectious diseases, including some which could have been transferred to the lynx from domestic animals or other wild animals such as panleukopenia and sarcoptic mange. If only radio-tagged animals (included in a monitoring program) were taken into consideration, the percentage of mortality caused by infectious diseases rose to 40%, indicating that infections might be underestimated in randomly found mortality events. We hypothesize that even a few cases of infections in a small population like the lynx, which are additionally threatened by noninfectious causes, may threaten the long term survival of the population. https://www.ncbi.nlm.nih.gov/pubmed/11838233
Large Impact of Eurasian Lynx Predation on Roe Deer Population Dynamics
Abstract__ The effects of predation on ungulate populations depend on several factors. One of the most important factors is the proportion of predation that is additive or compensatory respectively to other mortality in the prey, i.e., the relative effect of top-down and bottom-up processes. We estimated Eurasian lynx (Lynx lynx) kill rate on roe deer (Capreolus capreolus) using radio-collared lynx. Kill rate was strongly affected by lynx social status. For males it was 4.85 ± 1.30 S.E. roe deer per 30 days, for females with kittens 6.23 ± 0.83 S.E. and for solitary females 2.71 ± 0.47 S.E. We found very weak support for effects of prey density (both for Type I (linear) and Type II (non-linear) functional responses) and of season (winter, summer) on lynx kill rate. Additionally, we analysed the growth rate in a roe deer population from 1985 to 2005 in an area, which lynx naturally re-colonized in 1996. The annual roe deer growth rate was lower after lynx re-colonized the study area, but it was also negatively influenced by roe deer density. Before lynx colonized the area roe deer growth rate was λ = 1.079 (± 0.061 S.E.), while after lynx re-colonization it was λ = 0.94 (± 0.051 S.E.). Thus, the growth rate in the roe deer population decreased by Δλ = 0.14 (± 0.080 S.E.) after lynx re-colonized the study area, which corresponded to the estimated lynx predation rate on roe deer (0.11 ± 0.042 S.E.), suggesting that lynx predation was mainly additive to other mortality in roe deer. To conclude, this study suggests that lynx predation together with density dependent factors both influence the roe deer population dynamics. Thus, both top-down and bottom-up processes operated at the same time in this predator-prey system. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4373782/
Density of Wild Prey Modulates Lynx Kill Rates on Free-Ranging Domestic Sheep
- John Odden , Erlend B. Nilsen, John D. C. Linnell
Understanding the factors shaping the dynamics of carnivore–livestock conflicts is vital to facilitate large carnivore conservation in multi-use landscapes. We investigated how the density of their main wild prey, roe deer Capreolus capreolus, modulates individual Eurasian lynx Lynx lynx kill rates on free-ranging domestic sheep Ovis aries across a range of sheep and roe deer densities. Lynx kill rates on free-ranging domestic sheep were collected in south-eastern Norway from 1995 to 2011 along a gradient of different livestock and wild prey densities using VHF and GPS telemetry. We used zero-inflated negative binomial (ZINB) models including lynx sex, sheep density and an index of roe deer density as explanatory variables to model observed kill rates on sheep, and ranked the models based on their AICc values. The model including the effects of lynx sex and sheep density in the zero-inflation model and the effect of lynx sex and roe deer density in the negative binomial part received most support. Irrespective of sheep density and sex, we found the lowest sheep kill rates in areas with high densities of roe deer. As roe deer density decreased, males killed sheep at higher rates, and this pattern held for both high and low sheep densities. Similarly, females killed sheep at higher rates in areas with high densities of sheep and low densities of roe deer. However, when sheep densities were low females rarely killed sheep irrespective of roe deer density. Our quantification of depredation rates can be the first step towards establishing fairer compensation systems based on more accurate and area specific estimation of losses. This study demonstrates how we can use ecological theory to predict where losses of sheep will be greatest, and can be used to identify areas where mitigation measures are most likely to be needed. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0079261
Mortality in the Eurasian lynx population in Croatia during the 40 years
Magda Sindi , Tomislav Gomerˇ, Josip Kusak , Vedran Slijep cevi , Ð uro Huber ,
Alojzije Frkovi ́
Suggests mortality may be about 15%, but the most important factors are human related, eg Shooting, poaching, trapping and motor accidents. More males are shot than females, probably due to their larger territories. Main month for mortality is February, with 32 deaths in study of which 10 were kittens and 22 were adults.
Roe deer face competing risks between predators
along a gradient in abundance
Melis, C., E. B. Nilsen, M. Panzacchi, J. D. C. Linnell, and J. Odden. 2013. Roe deer face competing risks between
predators along a gradient in abundance. Ecosphere 4(9):111. http://dx.doi.org/10.1890/ES13-00099.1
Vulpes vulpes the Red Fox http://bioweb.uwlax.edu/bio203/f2013/eidensch_matt/interactions.htm
Game and Wildlife Trust Conservation surveys
Commissioned by the Deer Commission for Scotland
A review of available data on natural mortality of red and roe deer populations.
Major causes of deer mortality include harsh winter
s, disease, poaching, predation,
and deer-vehicle collisions (Harris et al. 1995, P.
O.S.T. 2009, Langbein 2011). However,
by far the biggest cause of mortality is culling; a
lthough nearly 35000 deer are culled
annually in Britain, this number will need to be in
creased if we are to keep populations
in check (P.O.S.T. 2009).
- Milder winters;
- Changes to agriculture such as the planting of winter crops;
- Increased woodland cover;
- Escapes and releases from parks and farms; and
- Greater connectivity between green spaces in urban areas
Predation has a greater impact in less productive environments: variation in roe deer, Capreolus capreolus, population density across Europe
Behavioural and spatial adaptation of the Eurasian lynx to a decline in prey availability
Home range sizes of lynx showed a tendency to increase with declining prey densities, as indicated by relative percentage increases in average yearly home range sizes amongst different sex/age groups. In response to lower availability of their main prey, lynx increased their daily straight-line movement distances by 44% and doubled the ranges covered in 5-day periods. This illustrated that, with declining prey abundance, the lynx increased their hunting efforts by either spending more time actively searching for prey or continuing foraging even after a successful hunt. Spatial analysis of the distribution of ungulates and lynx indicated that deer were evenly distributed throughout lynx ranges in BPF and spatial proximity of the predator to prey sites did not play an important role in the efficiency of hunting. Lynx may adapt to changing prey availability by increasing search effort, but this was not sufficient to prevent the negative influences of the prey decline on the lynx population. Prey depletion has an immediate effect on lynx spatial organization and, in consequence, on their density. This information has to be considered in prioritizing lynx conservation measures and management of ungulates
- 22 June 2016
Plans to reintroduce the lynx to the wild in Cumbria and Norfolk have been scrapped.
The Lynx UK Trust said the animal, which has been extinct in Britain for 1,300 years, would help control deer populations and attract tourists.
But it has now ruled out Ennerdale in the Lake District and Thetford Forest in Norfolk, as too small to support populations of the big cat.
Sites in Northumberland and Scotland are still being considered.
Opponents argued the animals would be a threat to livestock and wildlife.
Dr Paul O’Donoghue, chief scientific advisor with the Lynx UK Trust, said Kielder Forrest in Northumberland and two further sites in Scotland had a “much stronger” suitability due to factors such as bigger forest blocks and fewer roads.
The trust previously said it wanted to place up to six lynx at different sites across the UK as part of efforts to repopulate the species and has targeted lodging a formal application with Natural England to begin the trial later this year.
However, the National Sheep Association (NSA) expressed fears the move could damage the livelihoods of farmers.
Chief Executive, Phil Stocker, said: “NSA has been active in highlighting the many reasons why the UK is unsuitable for this project and is pleased that these reasons have forced Lynx UK to discount the Lake District and Thetford Forest as potential release sites.
“Our work will now continue to highlight issues with the sites in northern England and Scotland still under consideration.
“It is unacceptable to threaten the welfare of sheep and the livelihood of farmers with this scheme and it is NSA’s aim to ensure Lynx UK and its supporters cannot continue to ignore the vital role of sheep in underpinning countryside management and supporting rural communities.”
Consultation underway for lynx reintroduction
Following the recent submission of an application for a trial reintroduction of lynx into Kielder Forest, UK, the Lynx UK Trust has announced that it has continued with further consultations.
The consultations focused on Argyll and Inverness-shire in the Scottish West Highlands.
For the previous 12 months, the Lynx UK Trust has been in discussions with major landowners regarding a trial reintroduction of Eurasian lynx in Argyll and Inverness-shire, confirming access to potential release sites in each county.
The Trust aims to explore the potential for lynx in the area, including benefits it could bring to the ecology by controlling deer populations and helping to protect the capercaillie, the endangered largest member of the grouse family of wild fowl.
Deer are well known to be over-populated in Scotland, damaging forest habitats and restricting forest regeneration. A reintroduction of the lynx is expected to act as a potential natural control to help with the problem.
Dr Paul O’Donoghue, chief scientific advisor for the trust, said: “This is a classic example of the negative impacts that come with removing species like the lynx from an ecosystem.
“Over development and climate are certainly having an impact on capercaillie but the elephant in the room is the exploding pine marten population. It’s fantastic to see them doing so well, but too much of anything creates imbalances, and they have a big impact on capercaillie by stealing their eggs.
“Pine marten overpopulation is a direct result of them having no natural predators in the ecosystem.”
“The effect has already been observed in Europe,” continues O’Donoghue, “Scottish forest ecosystems are wildly out of balance; overpopulations mirrored by underpopulations of iconic Scottish species such as the capercaillie, now on the very edge of extinction in Scotland.
“Without doubt, lynx can help restore some balance and save this species.”
Plans submitted for lynx to be reintroduced at Kielder Forest
Eurasian lynx Photo: Chris Godfrey
The Lynx UK Trust has submitted an application to Natural England for permission to carry out a trial to reintroduce the medium-sized wild cats into Kielder Forest in Northumberland.
It is the first time an application has ever been made in the UK for this species or any apex predator.
If permission is given, six Eurasian lynx (four females and two males) will be reintroduced in the Kielder Forest region for a five year period, wearing satellite collars to monitor their movements.
The application comes just over a year after the Lynx UK Trust announced their intentions to explore the possibility of bringing the Eurasian lynx back into the British ecosystem.
It’s likely the wild cats were wiped out by fur hunting and the loss of their natural habitat. But, the trust says their absence has contributed to an over population of their favourite prey; roe deer. Currently estimated at double the sustainable population size, the UK’s deer species are said to be damaging the UK’s native forest ecosystem causing problems all the way down the food chain.
Eurasian lynx have already been successfully reintroduced in countries including Germany, France and Switzerland. There are now thought to be around 10,000 of them across Europe, when numbers had dropped as low as 700.
The Lynx UK Trust says reintroducing them into Northumberland could be a major boost to the tourism industry.
Lynx have a shy and secretive nature that makes them a perfect reintroduction candidate; no attacks on humans have ever been recorded by a healthy, wild Eurasian lynx anywhere in the world. They have a very low impact on livestock with lynx in Europe killing, on average, less than one sheep every two years. The charismatic cats can also be major drivers of rural economies with the potential to brings tens of millions of pounds of tourism money into the Kielder region.”
– The Lynx UK Trust
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Eurasian lynx Credit: Chris Godfrey
An international team of experts have spent the last year detailing an approach to a reintroduction, consulting with national stakeholders, studying potential release sites, and consulting with local communities and businesses about the lynx and how a reintroduction might look.
Their findings have been extensively recorded and submitted this week to the statutory agency responsible for licensing species reintroductions in England, Natural England.
Whilst any releases would take place in England, the lynx may cross the border into Scotland and as such Scottish Natural Heritage are also remaining fully informed of all details of the application.
The Chief Scientific advisor on the project, Dr Paul O’Donoghue, said: “It is incredibly exciting to see it all come together…”
Tens of thousands of man hours of work by a huge team of people have gone into consultations shaping this final application which marks a significant milestone in the history of UK conservation; potentially the first return of an extinct predator, which could prove to be a really keystone species for our ecosystem.
“And the Lynx can bring huge benefits to the Kielder region; we could see a wave of economic regeneration as it becomes known as the kingdom of the lynx; a unique eco-tourism destination right in the middle of Britain. We’ve had a lot of positive feedback from local businesses and it would be amazing to work with them developing that, from the Angler’s Arms pub in Kielder Village, already sporting a life-size replica lynx above the bar, to all kinds of new guest houses, guided walks and wildlife watching activities creating new jobs in the area.
“We’ve now reached a point where we feel every piece of research has been done, every concern that can be raised has been raised, and the only way to move truly forward is with an intensively monitored trial reintroduction of a small number of cats. That can tell us exactly how suitable the lynx would be for a larger reintroduction. We very much hope the lynx has the opportunity to prove it can bring so much to the local community and the UK as a whole.”
The Trust will now wait on a response from Natural England.
Last updated Mon 17 Jul 2017
MINUTES OF THE 8th MEETING OF THE NATIONAL SPECIES REINTRODUCTION FORUM.
15th November 2013. Scottish Natural Heritage (SNG) Battleby
Agenda item 4.
Presentation and discussion of a proposal to reintroduce lynx to Scotland
For this item we were joined by Dr Paul O’Donoghue, Director of the Lynx UK Trust. Earlier in the year Dr O’Donoghue had stated that the Lynx UK Trust was interested in submitting a licence application to reintroduce lynx
to Scotland. Since any such proposal was likely to be of interest to a wide range of conservation and land use organisations, he was therefore
invited to the NSRF to set out his initial plans. The item began with a presentation from Dr O’Donaghue entitled a “Scientific trial to assess
the viability of lynx reintroduction into Scotland”. The scientific, economic and ethical reasons for undertaking a trial were set out, and some details on the methodology. The proposal would involve a three year local feasibility study, with an initial release of two males and four females which would be tracked using GPS collars, and a programme of post – release monitoring. The details of possible release sites were not given but discussions had been held with landowners. The importance of engagement with local communities/stakeholders was seen as essential. Impact on livestock would be measured and compensation paid for livestock lost. Discussions were also being made with key stakeholders in England and Wales to examine potential releases there.
The presentation was followed by a question and answer session, during which a number of issues were raised, such as the area required by the released lynx during a three year trial period, the criteria that would be need to judge the success or failure of any trial, and technical issues surrounding the use of GPS equipment.
There was a further discussion of the proposal after Dr O’Donaghue had left the meeting , having been thanked for making the effort to travel to Battleby and give the presentation .
It was clear that the presentation had been thought provoking and had generated a lot of interest but there were a number of uncertainties or concerns over a range of issues (such as the lack of clarity over the selection of a trial site, resourcing, and how local people would
be engaged and involved).
It was agreed that SNH would try to summarise the comments
and views of NSRF members and send this feedback to him. It was also felt that any such project would need to take into account the issues and approaches set out in the Scottish Code for Conservation Translocations which is being drafted.
Action point 8.7
SNH to collate and send comments to Dr O’Donaghue
Application to Natural England for the Trial
Reintroduction of Lynx to England
Carcasses provide food source for mustelids. TB risk?
THE FEASIBILITY OF REINTRODUCING THE EURASIAN LYNX Lynx lynx TO SCOTLAND
David Andrew Hetherington
M.A. (Hons) Environmental Geography, University of Aberdeen, UK
………Skeletal remains of lynx have been recovered from cave sites across Scotland, England and Wales. Recently acquired radiocarbon dates, as well as etymological, linguistic and cultural evidence, show that lynx continued to
inhabit areas of northern Britain until at least the early mediaeval period. This contradicts theories that lynx died out in Britain because of climatic processes. Anthropogenic factors, such as severe deforestation, declining populations of deer, and persecution driven by protection of livestock, are
instead likely to have brought about the species’ extirpation in Britain. As lynx did not become extinct in Britain due to natural processes, they qualify ethically as a candidate for reintroduction. ……
………A Population Viability Analysis using the Leslie matrix-based software package RAMAS/age suggested that a lynx population living at a carrying capacity of 400 would be viable in the long term. However, a lynx population at a carrying capacity of 50 would be too small to be viable in isolation. Movement corridors between the Highlands and the Southern Uplands, which run through benign habitats and avoid significant barriers, are therefore essential for the long-term viability of a Southern Uplands lynx population. In order to have a high probability of surviving for 10 years after release, the minimum size of a founder population composed of 1 to 3-year old lynx should be 12 to 32 individuals, with an equal sex ratio. The most suitable lynx for a Scottish reintroduction would come from the wild of Latvia, Estonia and SW Finland……..
…….High densities of deer can have deleterious effects on forestry, agriculture and natural vegetation. Browsing, bark stripping, fraying and bole-scoring by deer can inflict substantial costs on the forestry industry in particular. The Forestry Commission owns around 35% of Scottish woodland and budgeted for a net deer management cost of £4.85 million for the year 2003/2004 (Hunt, 2003). These costs however do not include those
incurred through damage caused by deer to trees, which can be extensive. Forestry damage caused by deer in the Galloway area of south-western Scotland was thought in 1990 to be costing around £2 million per annum
(Allison, 1990). ………………
Stahl et al. (2002) identified three scenarios for the interaction of livestock and large carnivores in Europe: 1. Livestock receive high levels of protection
either by being fenced in, constantly herded by shepherds and/or dogs, or confined at night. These practices are typical of the Carpathian Mountains of Romania and Slovakia where numbers of wolf, bear and lynx are high. Under these circumstances, damage to livestock caused by lynx is non-existent or negligible, although wolves and bears can be problematic locally (Kaczensky, 1999; Mertens & Gheorghe, 2002; Rigg, 2003). ………………..
…………..This is typical of several parts of Norway where each summer over 2 million sheep are grazed in the forest (Odden et al., 2002). They are unsupervised and scattered as individuals or small groups over large areas of forest, thus replicating the behaviour and occurrence of roe deer, the lynx’s favoured prey. As densities of roe deer over most of Norway are low, lynx territories are much larger than those in other countries (Sunde et al. 2000b; Linnell et al. 2001a), and in those parts of Norway where free-ranging sheep
occur, most lynx will have sheep grazing within their home ranges (Odden
et al., 2002). This results in relatively high levels of depredation of sheep by
lynx and other forest dwelling carnivores. Almost all lynx, and especially males, are thought to kill sheep, although the roe deer remains the lynx’s
principal prey despite its limited abundance (Odden et al, 2002). Lynx kill several thousand sheep, mostly lambs, each year in Norway, with a high of 9000 in 1999 representing around 0.4% of the national flock 51 (Linnell et al
., 2000; Warren, Mysterud & Lynnebakken, 2001). The extent of the problem in Norway contrasts sharply with neighbouring Sweden, which supports a larger lynx population. Based on a Norwegian lynx population of 500 killing over 4700 sheep annually, and a Swedish lynx population of 1000 killing 48 sheep annually, Kaczensky (1999) calculated an annual loss per capita of lynx of 9.5 sheep in Norway, but less than 0.1 in Sweden. …….
………………As sheep are unevenly distributed in the landscape, only occurring in pastures, they are not found in the home range of every lynx. In addition, it is thought that the sudden and rapid movements of sheep in flocks may make hunting sheep more difficult for the lynx (Stahl et al ., 2002). spatial variability of sheep distribution combined with specific site factors, have resulted in sheep depredation by lynx involving only a few problem individuals at limited “hotspots”. Numbers of sheep killed or wounded by lynx in the French Jura vary from around 100-400 each year, but more than
70% of attacks occurred in nine small hotspots representing 1.5% of the area affected by lynx attacks (Stahl et al ., 2000; 2001b). The majority of affected sheep flocks in the French Jura experience only a very low level of depredation, i.e. 1-2 attacks per year……………
……………The distance of the pasture from woodland or scrub has a strong bearing on levels of depredation (Angst et al., 2000; Stahl et al, 2002). In the Swiss Alps, 88% of lynx kills occurred within 200m of the forest edge, and 95% within 360m (Angst et al., 2000). Sheep less than one year old are more susceptible than older sheep, with 78% of those killed falling into this age group. Of those sheep owners who lost livestock in the Swiss Alps from 1979-1999, 80% lost three or fewer sheep during this period (Angst et
al., 2000). In the French Jura, it was discovered that shooting a nuisance lynx would often solve the problem for a few months, but that ultimately a new lynx would take over the home range of the dead lynx and sheep depredation would commence once again (Stahl et al., 2001b). In these circumstances it is clear that site-specific, environmental factors are determining the likelihood and extent of depredation……………
………..4.1.2 Lynx habitat requirements 188.8.131.52 Home range prey, and the cover from which to hunt it, are the major natural constraints on lynx range
and population density in the temperate and boreal zones (Breitenmoser et al
., 2000). Small ungulates are the most important prey item for the Eurasian lynx, and where they are found, roe deer are usually the single most significant prey species. Indeed, lynx and roe deer are virtually sympatric right across Eurasia. Roe deer are predominantly browsers and are found most often in coniferous and broadleaved woodland, or in open areas near to the woodland edge (Fawcett, 1997). Wooded habitats, therefore, provide the lynx with an important food resource and, as the lynx is an ambush hunter, also the cover in which to stalk its prey. However, some areas of lynx range in Eurasia are not well wooded, and so roe deer are scarce or absent (Breitenmoser et al., 2000). In these cases, lynx use the available cover to hunt other species. For example, in the Swiss Alps, lynx often forage above the altitudinal treeline, using montane shrub and rocks to ambush chamois, while in the mountains of Central Asia lynx exist in treeless environments
, hunting instead on scrubby mountainsides (Breitenmoser et al., 2000…….
………..184.108.40.206 Dispersal Juvenile lynx usually become independent of their mothers at between 9 and 11 months of age (Schmidt, 1998). At this stage, they disperse from their mother’s home range in search of a home range of their own, and they may have to travel some distance to settle in an unoccupied territory. For example, in the Swiss Jura Mountains, dispersal distances for 11 subadult lynx varied from 11 km to 98 km, with a mean of 43.4 km (Zimmermann, 1998). In the Swiss Alps, 19 subadult lynx were followed with radiotelemetry which revealed dispersal distances from 2 km to 164 km, with a mean of 68 km (Breitenmoser-Würsten, et al, 2001). In Bia
Łowież a Primeval Forest in Poland, six subadult lynx dispersed between 5 m and 129 km, with a mean distance of 42.5 km (Schmidt, 1998). In north-east Poland, subadult lynx followed areas of forested habitat during their dispersal, and open farmland appeared to be a barrier, with lynx changing direction whenever they encountered it (Schmidt, 1998)………..
………..In Switzerland, where lynx have adapted to more open environments, roaming lynx can use other land-uses during their dispersal. In the Swiss Jura, although 75% of radiotelemetry locations from dispersing lynx came from woodland, 25% were in open habitats, such as natural open habitats (11%), pasture (11%) and agricultural land (3%) (U. Breitenmoser,
pers. Comm .). Nevertheless, lynx tend to use woodland and scrub as they move across the landscape and are rarely more than 400 m to 500 m away from such cover (Zimmermann & Breitenmoser, in press ). Lynx have also been recorded swimming up to 30 m across rivers and 200 m across lakes (Zimmermann & Breitenmoser, in press). Furthermore, despite stronger habitat preferences than other European large carnivores (Breitenmoser, 1998), lynx have shown adaptability in human-modified landscapes. radiotelemetry from Switzerland has revealed that lynx will often rest during
the day in close proximity to human settlements, roads, golf courses, logging areas, ski lifts and even military training areas when shooting is actively underway (Zimmermann & Breitenmoser, in press) …………
………….3.The minimum patch size capable of containing a female home range was 45 km². For patches to support both a male and a female, the minimum patch size was 74 km².
4.A habitat patch capable of supporting one or more lynx must contain
≥24 km² of woodland and be ≥ 38% forested. ……………….
………….. Continued in table on next page
Continued from previous page
lynx diet (%)
lynx diet (%)
Table 5.1 Percentages of age/sex classes of roe and red deer killed by lynx in
Białowieża Primeval Forest, Poland during 1987/88-1996, compared to their mean percentages in the living populations in March.From Okarma et al.(1997)…………………..
|Age (years)Female first breed||2|
|Max age (years)||14|
|Sex ratio at birth||1:1|
|Annual survival of female age 0-1||0.5|
|Annual survival females age 1-2||0.75|
|Annual survival females age 2+||0.7|
Table 6.2. Lynx life history data (part of table, survival rate rounded figures from Norway)
So, sheep are a normal, though small, part of the Lynx diet. There is evidence that sheep predation happens when roe Deer density falls. 95% of sheep killed by Lynx are free ranging mountain lambs. In one study a density of 6.5lambs per square kilometre was regarded as a high density, and if Roe deer were scarce a male Lynx would kill about 6 lambs over a 30 day period. Though males sometimes killed 6 at one time. Females kill fewer lambs and when Roe Deer are abundant, do not take lambs.
When Roe deer are plentiful Lynx prey on them to the exclusion of other prey, and this makes sense when one considers their apparent vulnerability to non-infectious diseases, probably resulting from wound when hunting unfamiliar prey. (see below) This may explain their normally solitary habit as they also appear to be vulnerable to infectious disease caught from other Lynx.
Lynx are thought to have become extinct in the UK in about AD400. Their main prey the Roe Deer almost became extinct in the UK in AD1700, and that population decline could not have been due to to predation by the Lynx, which had been extinct for 1300 years.
Lynx live mainly in forest, but can also live in open country, including for example barren rocky areas above the tree line. The territory of a single male Eurasian lynx can extend to 1000 sq km, or about three times the area of Kielder Forest, so even if a Lynx has all it needs within the forest they are quite capable of making long excursions outside the boundaries.
Lynx eat approximately one Roe deer a week, or 60 a year. There are estimated to be about about 6,500 roe deer living within Kielder forest (or about 4% of the English population of roe deer) , so once Lynx are introduced there is potential for a population explosion, to perhaps 15 Lynxes before the population of Roe deer is affected. The smallest territory occupied by Lynx is about 100 Sq Km, so once the population of Lynx exceeds 4 animals their territories will have to expand beyond the boundaries of the forest. To start with, part of each territory may be in the forest where there would still be plenty of deer, but in patrolling the boundaries of their territory male Lynx will come into contact with prey that are not roe deer, and sheep will be at risk.
The Deer Initiative blame the following factors for the increase in wild deer populations
- Milder winters;
- Changes to agriculture such as the planting of winter crops;
- Increased woodland cover;
- Escapes and releases from parks and farms; and
- Greater connectivity between green spaces in urban areas
Milder winters are a very likely contribution as about 20% of Roe deer mortality is said to be the use of winter crops in farming may explain increase of due to winter cold. The milder winters also mean that many plants have a longer growing season and growth starts earlier in spring, meaning that a week animal does not have to wait as long for an improvement in diets. Farmers use of winter crops might explain some increase of deer populations in arable areas, but surely not in grassland areas to the west of the UK, though even here the change to continental breeds of cattle may leave fields vacant for longer.
In Scandinavian studies deer populations were between less than 1 per sq km to over 2.7 per sq km. At the lower of deer population (below 1 roe deer per sq km or 2.6 per sq mile) Lynx killed free ranging sheep in their territories. At a deer population of 2.7 roe deer per km sq(or 7 per sq mile) Lynx did not kill sheep in fields with electrified “predator proof” fences. The population density of roe deer in Kielder forest is 26 per square km. At this deer population it seems likely that the population density of Lynx will depend on social factors, with mortality due to fights for territory and general aggression between males, and the emigration of subdominant males and young adults.
It seems likely that the population of Roe deer in Kielder forest is currently being controlled by foxes, opportunistically taking fauns. The introduction of Lynx may reduce the fox population as Lynx will kill foxes.
Population dynamics of Roe deer has not been a popular area of study and published data is usually more about sustaining levels for human hunters, or protecting trees, rather than providing knowledge of Roe deer. Mortality in radio tagged Roe deer appears to be 20% due to disease, cold, starvation etc. predation could be up to 50% from Lynx and 30% to foxes. However, these studies on deer that have died only indicate what small numbers of deer have died of and do not indicate the effect of an introduced predator on a natural population of deer. In Kielder Lynx will use up the land area before they have much effect on the deer population, so opportunist control by foxes will e likely to remain the main mortality factor.
The following statement indicates the reason why it is particularly difficult to assess te affacte of introducing a new predator “Major causes of deer mortality include harsh winters, disease, poaching, predation, and deer-vehicle collisions. However, by far the biggest cause of mortality is culling;” (G Palmer)
The roe, are less social, resident species, which are also selective foragers. Given
their small body size and physiology, these species select easily digested, high-quality vegetation such as new growth of grasses and tree leaves. Shoots of Rubus species are the main component of their diet, but they also eat many other plants including ivy, grasses, root vegetables and the shoots of broadleaved trees such as beech Fagus sylvatica and holly Ilex aquifolium. Roe deer are usually solitary or found in pairs of either mating male and female, or a female and offspring. The home ranges of females sometimes overlap, but individual core ranges are exclusive. Males aggressively defend their territory from other males during the rut, which occurs during July and August for roe deer. Roe deer are associated with deciduous or open coniferous woodland, occurring at high densities in young woodlands. during the autumn and winter.
The preference for young growth suggests that the Roe population of Kielder forest will decline as the trees mature, after which their “less social” behaviour will make them less susceptible to predation then sheep which are more social.
Figure 1 From G Palmer PhD Thesis (MaxK is numbers per Km sq)
Males and females occupy overlapping territories, (In some studies male territories encompassed two female territories.) but are solitary hunters, so probably do not share prey. This information confirms the predictions in the last paragraph. Breeding takes place in February and March so after a 2-month gestation period kittens are born in April and May being weaned 6 months later, probably in June and July. Thus the most active period of the Lynx’s life coincides with the traditional lambing period and the period until lambs are weaned.
Kittens are fully independent at 10 months probably in about February, suggesting a great deal of disruption in Lynx communities as newly independent animals will be competing with their parents for food at the same time as their parents are starting to breed. This implies a time when some young Lynx will be forced to set up new territories outside Kielder forest.
A simple calculation of population growth, assuming a mature pair introduced in year 1 and that 3 kittens survive from each mating, suggests that by the time that the first adults die – in their mid-teens, say 15 years, and each new pair breeds first in their third year, there could be 30 Lynx in Kielder forest, which would be unsustainable. A study on Lynz mortality in Switzerland suggests that the biggest cause of mortality is accident, or non-infectious diseases (presumably infections resulting from hunting injuries, or fights over territory) 18% of deaths were due to infectious diseases some of which would have been caught from domestic animals.
In practice mortality is likely to increase sometime after the population exceeds 4 territory holding males and territories start to expand beyond the forest itself. At this point, aggressive encounters by males defending territory will increase, and so will encounters with domestic animals from which the Lynx can contract infectious diseases. There will be a further increase in mortality when the number of Lynx in the colony exceed 15 and the population and growth rate of Roe Deer starts to decline. At this point there will be regular sheep kills by Lynx living outside the forest, and there may begin to be organised attempts at culls of Lynx.
Note that Lynx trust suggests smallest territory is only 40sq km. (probably for single females?)
- No change to control of deer in Kielder forest. Population will rise to about 120,000, ground and shrub vegetation will decline by about 20% as will deer sensitive woodland birds. Timber productivity will remain largely unchanged.
- As single female Lynx is introduced, deer population and other wildlife will be largely unaffected. (the Lynx will only eat 60 deer a year, perhaps less)
- A breeding pair is introduced. After about 8 years the Lynx population will have risen to a level where it will begin to have an effect on deer population, but competition between Male Lynx for territory mean that some lynx will have territories outside the forest, or sveral will have part of their territories outside the forest. From this point sheep kills will increase, as will road traffic accidents or even Lynx culls.
1sq km = 0.386sq miles
1sq mile = 2.59 sq km
O area of Kielder forest = 250 sq miles =648sq km
Male Lynx territories occupy about 100sq km females about 50sq
6,500 Roe deer in Kielder forest = 10 /sq km IN Scandinavian studies 2.6 / sq km was considered a high population