Taxon Surrogate Profiles Europe # 6: Caprinae Part 1

          The Caprinae are a subfamily of the Bovidae family which includes goats, sheep, and their relatives. In modern times there are three genera of the Caprinae that are considered native to Europe, including a combined seven species. The first is the Capragenus, which includes the four European species of ibex: the Anatolian ibex (Capra aegagrus), the Caucasian ibex (Capra caucasica), the Alpine ibex (Capra ibex), and the Iberian/Pyrenean ibex (Capra pyrenaica). The second genus is Rupicapra, which includes the two species of chamois: the Iberian/Pyrenean chamois (Rupicapra pyrenaica) and the European chamois (Rupicapra rupicapra). The last genus is Ovis, which includes the wild sheep, or mouflon (Ovis orientalis). The geographic history of these species within Europe is complicated, and there was a fourth genus present in the area during the mid-late Pleistocene, which will also be discussed. Muskoxen and their extinct relatives (Ovibos, Praeovibos, Soergelia, etc) are also part of this subfamily, but they will be discussed in the next article.

            First, the ibex. The genus Capra was once found across every mountain range and rocky habitat in central and southern Europe. The Anatolian subspecies of the bezoar ibex (Capra aegagrus aegagrus), the smallest of the European ibex species at a maximum weight of ~90 kg, is found in the rocky habitats of Turkey and adjacent Armenia, Azerbaijan, and Georgia, in addition to several countries not generally considered to be part of the European continent. This taxon represents the ancestral stock from which all domestic goats descend, and is still found in a large portion of its previous distribution. Despite this, it is considered vulnerable by the IUCN and has suffered population reductions in some regions due to poaching, trophy hunting, habitat loss, and hybridization with its domestic relatives. These factors have led to its complete extirpation from several areas, including most of western and northern Turkey. Nearby, in the Caucasus mountains, including Georgia and the adjacent regions of Russia, the Caucasian ibex is found. Traditionally this species was split into two, one for the western part of the mountain range and one for the east, but this has since been reconsidered so that that they are now considered subspecies: the western Caucasian ibex (Capra caucasica caucasica) and the eastern Caucasian ibex (Capra caucasica cylindricornis). At a maximum weight of ~140 kg, this is the largest of the European ibex species. While the western subspecies is considered endangered, the eastern is listed only as near-threatened. This species has the smallest original distribution of the four European ibex species, and consequently has the fewest opportunities for reintroduction. The protection of its existing habitat is very important to it continued survival.

            The Alpine ibex, of which there are no recognized subspecies and which is considered to be least concern by the IUCN, seems to have suffered the greatest range reduction out of these four species. Present only in the Alps today, this species was also present in the Tatras, Balkans, and Dinaric mountain ranges until the mid-Holocene, and the Carpathian and Apennine mountain ranges until at least the late Pleistocene. Extirpated from everywhere but the French and Italian Alps by the early twentieth century, the ibex has since been reintroduced to the alpine regions of Austria, Germany, and Slovenia. Reintroduction attempts have also been made in Slovakia to replace the extinct Tatras population, but the project failed due to the animals being not only of Alpine stock, but also of Anatolian and even Nubian (Capra nubiana) individuals. At the time these ibex varieties were considered to be subspecies of each other, and it was thought that a broad genetic base would increase the likelihood of a successful introduction. However, the hybrids molted at the wrong time of the year, due to the adaptations inherited from their more desert-adapted ancestors, and the population did not survive the winter. Future attempts should use only non-hybridized C. ibex. A population also exists in Bulgaria, imported for sport. These animals are often treated as alien, but their Holocene fossil record in the area suggests that they are better thought of as a reintroduced species. Further reintroductions to the Balkans and Dinarides should be a part of any rewilding projects in those areas. I would also put forward that the Apennines and Carpathians should be considered for reintroductions as well.

            The last of the European ibex species is the Iberian ibex. In modern times there have been four subspecies of this ibex living in the Iberian peninsula. These were the eastern Spanish ibex (Capra pyrenaica hispanica), the Portuguese ibex (Capra pyrenaica lusitanica), the Pyrenean ibex (Capra pyrenaica pyrenaica), and the western Spanish ibex (Capra pyrenaica victoriae). Of these, the eastern variety is considered least concern, the western is vulnerable, and the Portuguese and Pyrenean are extinct, the former since the late nineteenth century, and the latter since the early twenty-first century. Both were victims of hunting, competition with livestock, and habitat loss. The Pyrenean subspecies is notable for having gone extinct twice: first in 2000 when the last wild individual was hit by a fallen tree, and again in 2003 when a kid was cloned from material taken from this individual, only to die after several minutes. It is my opinion that future cloning efforts should be reserved for species with more unique evolutionary/ecological histories, and that the best option for the Pyrenean ibex is to create new populations using another subspecies, something that has already been considered by French organizations. It may be possible to integrate the genetic material of the Pyrenean subspecies into these populations in the future. The Portuguese subspecies is in the process of being replaced by the western ibex subspecies through natural dispersal and translocation.

            Moving on to the chamois group. The Pyrenean chamoi has three living subspecies, all of which are considered least concern by the IUCN, these are: the nominate subspecies (Rupicapra pyrenaica pyrenaica), which occupies the Pyrenean mountains of southwestern France and north-eastern Spain, the Cantabrian chamois of north-western Spain (Rupicapra pyrenaica parva), and the Abruzzo chamois (Rupicapra pyrenaica ornata) of the Italian Apennines. Fossil records indicate that the Pyrenean chamois used to occupy the entirety of the Iberian peninsula until they were extirpated from Portugal and most of Spain in the middle Holocene. It is unclear if these populations were referable to the Cantabrian subspecies or to some extinct group, but either way the possibility for a redistribution of the species across the peninsula could be possible, especially with the increasingly low population densities in some areas of Iberia. The other chamois species has a much larger range and a greater diversity of subspecies. The nominate subspecies (Rupicapra rupicapra rupicapra) is found in the Alps, and there are also Balkan (Rupicapra rupicapra balcanica), Carpathian (Rupicapra rupicapra carpatica), Carthusian (Rupicapra rupicapra cartusiana), Anatolian (Rupicapra rupicapra asiatica), and Caucasian subspecies (Rupicapra rupicapra caucasica), in addition to a critically-endangered subspecies from the Tatras (Rupicapra rupicapra tatrica). Populations of all these taxa have undergone reductions in their distributions, and have become heavily fragmented by habitat loss. A priority for their recovery will be to improve connectivity between their pockets of occurrence.

            As for the third genus, Ovis, the history in Europe is a little more complicated. The current representative of the wild sheep in Europe is the European mouflon (Ovis orientalis musimon). This population descends from wild sheep found on the islands of Corsica and Sardinia, which were later imported to the mainland for hunting purposes, where they have since become very widespread. The problem is that the original stock were not as wild as originally thought, being the descendants of an early variety of domestic sheep (Ovis orientalis aries), which were able to go feral on these islands only due to the lack of large predators. They display very domestic behaviours, preferring lowland habitats to rocky highlands, and being very easily taken by predators, so much so that when predators have returned to certain areas in the past, the local mouflon population has disappeared completely. This needs to be considered if mouflon are to be used in rewilding projects. One approach is to use one of the truly wild subspecies instead, such as the wild sheep of the Transcaucasian region (Ovis orientalis gmelini) which should be better adapted to predation and to harsh terrain. This subspecies is threatened, and expanding its distribution would certainly help in its conservation. We would have to be prepared for the possibility of hybridization with existing populations of the European variety, but this is to be expected, and it is possible that a combination of the two varieties would be quite suitable for multiple European regions, assuming that natural selection will favour crossbreeds which inherit wildtype behaviours. The original distribution of mouflon on the mainland included the Balkan and Italian peninsula, in addition to Turkey and Transcaucasia, but fossils of the genus Ovis have been found outside of this region as well, allowing for the possibility of their use in rewilding projects in most of the European mountain ranges. 

            The last genus I will be discussing in this article is one that no longer occurs in Europe, and that is Hemitragus, today represented only by the Himalayan tahr (Hemitragus jemlahicus). From the mid-late Pleistocene there was another species in this genus, known as the European tahr (Hemitragus bonali). This species would have coexisted with the other three genera, and had a range that included all of the same mountain ranges. There even exists cave art that appears to depict a tahr (alongside an ibex), displaying many of the features that define the living species, such as short horns and a thick mane of fur around the neck. Native only to the Himalayas today, the tahr has become an invasive species in many areas where it has been imported for game hunting, including Argentina, New Zealand, South Africa, and the southern United States. This ability to adapt to a range of habitats speaks well for their potential introduction to Europe as a replacement for their extinct relatives. It is unknown exactly how they would interact with the other Caprines, but its relative did so seemingly without competitive exclusion for hundreds of millenia, and the Himalayan species is sympatric with several related species, such as (depending on the region) bharal (Pseudois nayaur), argali (Ovis ammon), goral (Nemorhaedus goral), serow (Capricornis thar), and markhor (Capra falconeri). The ibex, mouflon, and chamois seem to avoid competition through living at different altitudes and through differences in the amount of browse or graze taken by each species. Presumably the European tahr would have fit into this dynamic somehow, but more research will be necessary to determine how, and if the living species would have similar interactions with its environment.

            Populations of all four genera would be predated on by wolves (Canis lupus), bears (Ursus arctos), and lynx (Lynx lynx). Their re-establishment would also be an important preliminary step in the reintroduction of the leopard (Panthera pardus) to European rewilding areas. Human hunting of goat-like species is already a huge industry, and expansions and introductions would only reinvigorate that industry, with the understanding that offtake has to be sustainable. Wild meat and leather could be sourced from the offtake as well. These are also all species that people would potentially enjoy seeing in natural areas, and which could further stimulate ecotourism. Their ability to traverse uneven terrain will make them especially important for fighting succession and stimulating nutrient cycling in high altitude regions where larger herbivores like red deer and bison are less able to traverse the terrain. 

Taxon Surrogate Profiles Europe # 5: Bubalus

            Now for the last of the European bovines, the water buffalo. Unlike the bison (Bos bison) or aurochs (Bos taurus), the European water buffalo (Bubalus (bubalis?) murrensis) never returned to Europe after the last interglacial and eventually went extinct, possibly due to human presence in their glacial refugia. However the wild Asian water buffalo (Bubalus bubalis cf. arnee) made it to the eastern regions of Turkey, the Levant, and possibly the southern Caucasus during the early-mid Holocene, and the domestic descendants of the Asian species (Bubalis bubalis bubalis) have been common in eastern and south-eastern Europe for over a thousand years, where they have developed into robust and cold-resistant landraces. It would appear that buffalo still have an open niche in the European landscape, being more inclined to living in wetland habitats and consuming aquatic plants than their relatives in the genus Bos. It is unknown whether the extinction of the European species, which had disappeared from Europe and reappeared later several times as interglacial stages came and went, was ultimately due to human hunting or whether the species was naturally replaced in its refuges by the modern species, which was then prevented from recolonizing Europe by human activity. Frankly I’m not sure it matters, since the niche remains unfilled and either way it seems to me that humans are at least partially responsible for the lack of water buffaloes in Europe today.

            The question would then be how to go about restoring the water buffalo niche to the continent. The process is already partially under way in the form of local domestic buffalo being used in grazing projects for wetlands in the Netherlands, Romania, and elsewhere. These animals are resistant to European pathology, and acclimated to its temperatures and available forage. Much like horses, and unlike cattle, they retain a less derived, less heterogenous appearance, and distinguishing them from wild animals would be difficult to the untrained observer. Consequently, converting these herds to an aesthetically and behaviourally appropriate wild population is considerably less difficult. Feral water buffalo are already quite common in many places around the world, but seeing as their wild progenitors are still very much with us, we have the option to explore hybridization as a means of expediting the process. The purpose of hybridization in this case is mostly just to increase the size of the animals, which have undergone the standard dwarfing associated with domestication, and to reintroduce wildtype behavioural genes. Now, the European breeds of water buffalo are all of the river type (Bubalus bubalis bubalis), as opposed to the swamp type (Bubalus bubalis carabao). This is because they descend from animals of Indian stock, which were domesticated from the Indian/Nepalese subspecies of wild buffalo, Bubalus bubalis arnee. The swamp type buffalo has a different number of chromosomes, and was domesticated separately, probably from the Indo-Malayan subspecies, Bubalus bubalis theerapati. As a consequence, animals used for hybridization should be of the arnee type, which I believe are the only variety present in European zoos in any case. These will have the same number of chromosomes as the domestic stock we’ll be using, and will also be adapted to slightly cooler habitats, such as those they might encounter in the Himalayan foothills. Due to the fact that the introgression would be coming from the ancestor taxon, rather than just a related taxon in this case, it is less important that the breeding process exclude sex chromosomes or mitochondrial DNA from the wild species, since they will likely be very similar anyway. Selection of the resulting crossbreeds will also be much less extensive, since all we want is a larger animal with uniform colour and non-domestic behaviour. Once the correct genetic material is there to build off of, natural selection will do most of the remaining work.

            The European water buffalo’s former distribution suggests that it used riverways, such as the Danube and the Rhine, as a means of dispersal. It was never able to reach the Italian or Iberian peninsulas, possibly due to the absence of suitable pathways and an inability to cross the Alps or the Pyrenees. Resettlement of the genus should begin in Central European river deltas (the Oder Delta or Danube Delta, for example), allowing for natural dispersal elsewhere. Their suitability for other areas where their relatives never occurred will have to be decided on a case-by-case basis, and should take into account that buffalo fossils are very rare in Europe, and can be confused with bison or ox fossils, obscuring their true distribution. Buffaloes have already proven incredibly useful in the management of wetland areas, and a self-sustaining wild population will allow these effects to be much more widespread and cost-efficient, as well as providing an additional species for invigorating tourism and sustainable hunting practices.

Taxon Surrogate Profiles Europe # 4: Bos (taurus)

            Of all the proxies necessary to fully restore the European megafaunal assemblage, the aurochs (Bos taurus primigenius) is perhaps the most difficult to replicate in a satisfactory way. Attempts have been made for almost a century to breed them back in to existence through the crossing and selection of primitive cattle (Bos taurus taurus), but this has had limited success. Unlike horses, cattle do not go feral easily. Generations of selection for neoteny and docility have made even some of the least derived and demanding breeds feeble in comparison to their wild relatives. When they do live semi-feral they remain very habitat-specific and often require additional feeding. On top of that the traits known to have been possessed by the aurochs are spread very unevenly amongst its descendants, and animals showing more than half of them are very rare. You can certainly combine all of these traits in one population, but there is so much heterogeneity in cattle that getting them in one individual is almost impossible and getting them in enough animals to form a large founding herd has become a pipe dream. I’m going to posit some possible solutions, but I won’t pretend to know the best way.

            Probably the most straightforward way is to pursue cloning. We have DNA from several aurochs at this point and we can compare their genomes to that of living cattle. Unfortunately true cloning, wherein a living cell nucleus is implanted into a new egg and fertilized in a surrogate, is probably not possible as we would need an intact aurochs cell to start. Cloning only a few aurochs would be a poor start for genetic diversity as well, and you’d probably have to backcross them with cattle. However, direct splicing of wildtype alleles into a cattle genome might be possible if it were determined which genes were important. That might also be difficult considering how many genetic differences there might be, and the number of genes that might control things like body shape and horn size. There would be a lot of trial and error necessary to get it right, which is already the case with the breeding projects. Genetic engineering is also a very expensive process potentially, and though that may lessen over time, the effort necessary to identify important modifiers may remain high.

            Breeding primitive cattle over time is certainly cheaper, and perhaps more practical, but it definitely is not easy, and there are a million different opinions on the best way to do it. Forming a herd for conservation grazing using local cattle is easy enough, but these are still livestock under the law and will require additional feeding and veterinary care. Creating something that looks and behaves like a wild animal, and which can be left to its own devices with minimal human intervention, is considerably harder. There are certain breeds with a more aurochs-like phenotype than others, and this is especially true for some of the Lusitanian breeds like Sayaguesa (and their close relatives Serrana Negra and Alistana-Sanabresa), Tudanca, and Limia, but it also true for various breeds from across Europe. I certainly have my favourite breeds to use to meet this goal, but so does everyone else, and there will be issues regardless. Even the most primitive cattle have problems with hormonal expression, with this being less evident in fighting bull breeds, which still have some neotenous features. These lead to short faces, flat or concave backs with no shoulder hump, reduced sexual dichromatism, and long bodies with short legs. Basically, trying to breed an aurochs from a bull is liking trying to breed a wolf from a dog. You might get something that looks kind of like a wolf but it won’t act like one, and you’ll still get domestic features like floppy ears and white spots showing up.

            One potential method that might yield interesting results is hybridization. Now, I know that’s my solution for everything, but that’s only because I think it’s a legitimately useful tool for this kind of thing. Wild bovines have many of the traits we’re looking for in an aurochs effigy, there would just remain the question of which species to use. Bison (Bos bison ssp.) are out, since the aurochs and European bison were sympatric and we want to discourage hybridization in areas where both types of bovine are used. Yaks (Bos grunniensssp.) are in the bison lineage, so they should probably also be excluded. They do have some impressive horns, but they also possess many non-aurochs like traits associated with hair growth/colour and general body-form. Gaurs (Bos gaurus ssp.) share some ecological and morphological affinities with bison as well, and the kouprey (Bos sauveli) is likely extinct. That leaves the banteng (Bos javanicus). Now, while studies based on mitochondrial DNA place the banteng as being only distantly related to the aurochs, studies based on nuclear DNA, which I find more reliable, actually place it as being quite close phylogenetically. I think the Javan banteng (Bos javanicus javanicus), is the best variety to use, due to its perfect sexual dichromatism. The males are all dark brown to black, and the females all have an orangey-buff colour, a trait shared by the Eurasian aurochs. They are also the only banteng subspecies with the same number of chromosomes as cattle. An experiment breeding banteng to some of the more primitive Iberian breeds of cattle, like Sayaguesa or Maronesa, could potentially produce some very interesting results. There are two phenotypic traits that will have to be bred out, and potentially one or two behavioural ones, but the potential for hormonal improvement, non-domestic behaviour, and general robustness would make it worth it in my opinion. The white socks and rump of the banteng are dominant traits in existing cattle-banteng hybrids, making it an easy thing to breed out, which really just leaves the non-aurochs-like horns, which is already a trait that will need to be bred out in some of the primitive cattle breeds that might be used. Banteng also have a less confrontational style of fighting between bulls, but this may be selected out naturally. Something that is worth noting is that only the females of banteng-cattle crosses are fertile, and this will have to be accounted for in the breeding process. All backcrosses are fertile though, so that only affects the first generation hybrids. Apparently crosses with Indian cattle (Bos taurus indicus) which are also aurochs descendants, albeit of different subspecies (Bos taurus namadicus), produce fertile male offspring with banteng, but sources are a bit inconsistent on the matter. A hypothetical breeding plan would go as follows:

Male javanicusx Female taurus

-       F1 hybrid female, 1/2 javanicus, 1/2 taurus

-       javanicus X-Chromosome, taurus X-Chromosome and mDNA

Male taurusx Female F1

-       F2 hybrid male, 1/4javanicus, 3/4 taurus

-       taurus Y-Chromosome, either javanicusor taurus X-Chromosome, taurus mDNA

-       Select males that don’t show the banteng-type markings for breeding

Male F2 x Female taurus

-       F3 hybrid male, 1/8 javanicus, 7/8 taurus

-       taurus Y-Chromosome, taurus X-Chromosome and taurus mDNA

-       Integrate these animals into breeding-back herds to improve development and behaviour

Banteng are a tropical species, and this is worth noting for areas in central/northern Europe where cattle might be rewilded. Banteng are a hardy species, and cattle with slight banteng influence should do very well in most areas, as any climatic disadvantage should be counteracted by the adaptations of the base breed. For example, in the colder regions of the eastern steppe, a herd of 75% Podolian ancestry (ex. Maremmana, Podolica), 20% Lusitanian ancestry (ex. Sayaguesa, Limia), and 5% Javan ancestry might do very well. A herd in southern Spain might have similar proportions of Lusitanian and Javan ancestry, but be predominantly made of more arid-adapted Iberian breeds like Maronesa, Pajuna, or Lidia (fighting bull). What is important is that the herds can survive in the areas available to them without too much assistance, and that the desired traits are present in the herd to select upon over time. Natural selection will help this process along as well, as will occasional culling of bulls with an excess of undesired traits. I had originally planned to describe a similar plan to what I had proposed for horses, wherein different breeds become different varieties for the various European ecotypes, but due to the greater disparity in the appearance of wild vs domestic cattle when compared to horses, and the consequently smaller number of suitable breeds, there would probably end up being more like three or four types rather than nine, with herds in the colder regions of the north and east being descended from some of the same stock as those from founding herds in the south and west, only with greater proportions of ancestry from cold-adapted breeds. In general the strategy when forming new populations should, in my opinion, be to assemble herds of the most aurochs-like local cattle, or failing that the most aurochs-like cattle from a similar climate, and then slowly phase in breeds which possess desirable traits not found in the existing population. Certain breeds may be used to improve specific traits across several populations. As an example, the Chianina, from Italy, is one of the largest commercially-available breeds in the world and is itself a very old breed. Introgression from this breed, or from less common breeds of similar size (ex. Maltese cattle), could help to increase the size of aurochs-like cattle, which is important since the aurochs could be as tall as two metres at the shoulder, and weigh as much as a metric tonne, a size attained only by the largest of living cattle. Another breed, the Watusi of Africa, has also been used in breeding projects to contribute a greater horn size, as well as general robustness and improved ease of birth. The aurochs had very large horns and although many primitive European breeds possess horns of the right shape, they are of a smaller size which is a difficult thing to breed against if the genes aren’t there. The strategy with these breeds would not be to integrate them directly into existing herds, but to use them in the creation of individuals which will be integrated after a few generations of controlled breeding. 

            This is going to be a long process. It’s been going on, on and off, for almost a hundred years and we’re still not really there. Granted, we didn’t have the knowledge then that we have now, and progress has accelerated in the last twenty years, but cattle breed slowly and it can be very difficult to see progress in a short amount of time. It may be another fifty years of slow acclimatization and selection before we get an individual that’s sufficiently aurochs-like, and another fifty after that to get all of those traits in a population. We have to play the long game with this one, as is the case with many restoration efforts, but in the meantime we can build up primitive herds for use in our various European grazing projects and set the stage for the process to continue. This is going to be more difficult than it will be to re-establish herds of bison or water buffalo (which I will talk about in my next article), but it will be equally necessary for rewilding in areas where those species are not ideal. After all, all three varieties were once native to Europe, and each had their own unique ecological roles and habitat preferences. If you ask me, the more native megafauna we can restore, the better. Their environmental and economic benefits will become invaluable as land abandonment and vegetative succession continues.

Taxon Surrogate Profiles Europe # 3: Bos (bison)

            During the Pleistocene interglacials in Europe, there were three varieties of large bovine present in various habitats across the continent. These were the bison (Bos bison priscus/schoetensacki), the aurochs (Bos taurus primigenius), and the water buffalo (Bubalus (bubalis?) murrensis). Like the ass and the horse, these three species managed to live alongside each other through slight but significant differences in habitat and dietary preference. Where the buffalo preferred river valleys, swamps, and wetlands, the bison preferred drier mountain, steppe, and shrubland environments. In the meadows, pastures, and mixed woodlands in between is where you would find the aurochs. This is a similar situation to that seen in three sympatric bovines today in southeast Asia where the gaur (Bos gaurus hubbacki), banteng (Bos javanicus birmanicus), and water buffalo (Bubalus bubalis theerapati) coexist through a similar dynamic. Today, with modern rewilding initiatives, we have the opportunity to re-establish this ecological relationship in Europe again, the question is how to go about doing it, when all three of the native bovines have been reduced or altered with time. For this first article I will be discussing the process of rewilding European bison.

            The modern European bison (Bos bison bonasus) has a complicated taxonomic history. A couple years ago there was a lot of buzz around new findings that suggested it was the result of limited interbreeding between the steppe bison (Bos bison priscus) and the aurochs. However, several newer studies have rejected this theory, with more complete genetic evidence suggesting instead that they are a non-hybrid offshoot of the steppe bison that gradually adapted to different conditions. It is also becoming increasingly evident that the previous designation of bison as belonging to their own genus, Bison, is unwarranted, as they remain more closely related to some members of Bos(ex. Bos grunniens, the yak) than said members are to other species within the genus. Consequently it is now considered more appropriate to group bison into Bos, with the two previously recognized species in the genus, the American and European bison, being lowered to subspecies status, with each being a derivation of the ancestral steppe bison, and each remaining completely interfertile. All previously recognized subspecies are now better considered to be varieties or ecotypes. Another new study suggested that the European bison was a descendant of the Pleistocene species Bos bison schoetensacki, but that species has not been proven to have made it to the end of the Pleistocene, and it may be moot anyway since it was likely just an interglacial variety of the steppe bison in the first place. Bison morphology has been quite variable over time, responding to differing conditions and changing distributions, and there has been a tendency to overclassify, as is often the case when making taxonomic decisions based on morphology alone.

            Regardless of ancestry, the European bison is the only remaining member of the lineage in Europe, and consequently it is the most appropriate for use in European rewilding areas. This is already an ongoing process, with new herds being formed in many reserves across the continent. There does remain one problem however, and that is that the European bison suffers from interbreeding. To understand why, you would need some background on its conservation history. The European bison has been hunted by humans, both for food and for sport, for as long as the two have coexisted. The slaughter of the animal was so excessive that by the nineteenth century, there were only three populations remaining: one in the Polish lowlands (Bos bison bonasus var. bonasus), one in the Caucasus mountains (Bos bison bonasus var. caucasicus), and one in the Carpathian mountains (Bos bison bonasus var. hungarorum). The last of the Carpathian variety was shot in 1850, and the last of the Caucasian variety met a similar fate in 1927. Only the Polish variety survived, and only in captivity. Today there are two surviving lineages: the Lowland line which descends from seven “pure” Polish bison, and the Lowland-Caucasian line which descends from twelve polish bison as well as the last captive Caucasian individual. The first lineage understandably has a higher inbreeding coefficient than the second (44% versus 26%), but both lineages still have a high incidence of skeletal deformity, in addition to problems with their immune functionality and a general lack of robustness or adaptability. Genetic diversity has continued to decrease, and generations of captivity and/or winter feeding have left them less able to thrive on their own. Consequently, we need to look into strategies for increasing their genetic diversity and adaptability. It happens that there is already a very viable and effective option, but not everyone thinks it would be a good idea. 

In my opinion the best thing to do would be to experiment with controlled introgression of American bison (Bos bison bison) DNA into the European bison gene pool. Considering they are now considered by many to be the same species, it wouldn’t be entirely unreasonable. The same process I proposed for crossing wild and domestic horses in my previous article could also be used for crossing the two subspecies of bison, only I would recommend a greater number of backcrosses in order to preserve the phenotypic integrity of the European subspecies. The process would be something like the following:

Male bison x Female bonasus

-       F1 hybrid male, 1/2 bison, 1/2 bonasus

-       bison Y-Chromosome, bonasus X-chromosome and mDNA

Male F1 x Female bonasus

-       F2 hybrid female, 1/4 bison, 3/4 bonasus

-       bonasus X-Chromosomes and mDNA

Male bonasus x Female F2

-       F3 hybrids, 1/8bison, 7/8 bonasus

-       bonasus Y/X-Chromosomes and mDNA

F3 x bonasus 

-       F4 hybrids, 1/16 bison, 7/16 bonasus

-       bonasus Y/X-Chromosomes and mDNA

-       Intermix these individuals with existing herds to introduce new genetic material

There are two existing varieties of American bison: the American plains bison (Bos bison bison var. bison) and the Canadian wood bison (Bos bison bonasus var. athabascae). Despite not being particularly distinct from a phylogenetic perspective, they do have some noticeable aesthetic differences which might make one more appropriate for the introgression process than the other. Wood bison are perhaps optically more similar to the European bison than are the plains bison, being of a darker colour with larger horns. However it is worth noting that a mixed herd already exists in the Caucasus, where the reintroduced herds have about five percent of their DNA inherited from the plains variety, and seem to be thriving where attempts using pure bonasus herds failed. My thinking is that either of the North American varieties could be used, but maybe they should each be used for improving herds in different areas, with wood bison introgression for herds in the colder areas of central and northern Europe, and plains bison introgression for herds in the more arid and open areas of the south and east. In both cases animals which resemble the American subspecies too heavily will need to be sterilized or removed from the population, with the goal being to introduce new genes to the population without compromising the general appearance of the European subspecies. Attention will also need to be taken to ensure that animals with bisonancestry do not differ from pure bonasus individuals in diet or behaviour, since European bison do have a greater tendency to browse (though they are still primarily grazers) than American bison, and have a slightly different method of fighting for mates. An animal with over 95% bonasus ancestry would probably be basically indistinguishable from a pure individual, the only difference being the improved robustness and diversity.

The Lowland-Caucasian line is sometimes referred to as Bos bison bonasus var. montantus. I would tentatively suggest that a crossing of this line with these experimental bison-bonasushybrids might be called Bos bison bonasus var. robustus. I think these reinvigorated herds could potentially be very useful for rewilding areas of continental and northern Europe. They might also be of use in drier Mediterranean regions, where they actually seem to do quite well, based on observations of a breeding herd of the Lowland line in Extremadura. These areas were not occupied by bison in historic times, but were by various other members of the species during previous interglacials. In general they seem slightly more suited to living freely in arid scrublands than are various breeds of feral cattle. Fossils have also been found in the Anatolian region, suggesting these southern steppic regions are also suited to the European bison.

The European bison is the largest of the remaining European megaherbivores, and is consequently of great importance for re-establishing grazing dynamics across the continent. The regions available for the taxon remain limited, but there also remaining areas which have not yet been exploited, however small. Improving herd connectivity and available habitat is going to be a large part of their recovery. Their wild nature means that areas with large amounts of human traffic are not going to be suitable, further necessitating the need for creation and expansion of nature reserves in depopulating regions. I’ve discussed the generic positive effects of reintroducing large herbivores before, and bison will simply bring a similar, yet distinct version of the same effects. They will also bring benefits for the tourism and sustainable hunting industries, similar to the equids previously discussed.