As everybody reading my blog will know, Holocene Europe was originally home to two native bovines, the wisent and the European aurochs. But only the wisent survived, while the aurochs eventually died out in the 17thcentury, as a result of anthropogenic influence. But why did the aurochs die out while the wisent survived human activity until today?
It was two anthropogenic factors that drove the aurochs to extinction: one was hunting, the other one habitat limitation due to the expanding civilization. Both factors also apply in the case of the wisent. The wisent was also hunted, and its habitat was also limited increasingly as the human population in Europe grew continuously. So why did the wisent survive and did not die out at the same time the aurochs did?
One of the reasons might be that aurochs were hunted more intensively than wisent. Aurochs had larger, more impressively shaped horns and a colour that was more aesthetically appealing than that of the wisent (Sigismund von Herberstein wrote: “…the wisent is not as beautifully black as the aurochs…” in the 16th century), so that it is possible that trophy hunting focused more on the aurochs than on the wisent. Julius Caesar wrote in De bello gallico that the Germanic people liked to hunt the aurochs for its horns, while he made no mention of the wisent, although this species must undoubtedly have lived in the Hercynian forest as well.
Another possible reason why the wisent survived human activities while the aurochs died out lies in the ecology of both species. I outlined the ecologic differences between the two bovines in my post The ecologic niche of the aurochs. The aurochs was likely in direct competition with domestic cattle (and likely also horses) for feeding grounds. The aurochs was predominantly a grass eater, as are cattle and horses, and it is historically documented that aurochs grazed on the same places as the livestock of farmers, who chased the aurochs away if they encountered one on the pastures (see Anton Schneeberger’s report in Gesner 1602). During the last millennia and centuries of its existence, the aurochs retreated to wet habitats, such as swamps and marshes as isotope analyses show [1]. But also these areas were cultivated increasingly. The last historically documented population of aurochs, which lived in the forest of Jaktorow in Poland, disappeared because the space available to them became ever smaller and smaller as farmers continuously let their cattle and horses graze in the forests, so that the aurochs had to retreat even further and could not thrive [2].
The same problems also applied to the wisent. It, on the other hand, had the advantage that it could retreat to more mountainous regions (while the aurochs lived in even lowlands), which was less invaded by farmers or their domestic cattle and horses. Also, the wisent is more adapted to a forested habitat than cattle (and consequently likely also the aurochs), as they consume more wooden vegetation and need less grass in their diet [3]. The ecology of the wisent is probably the main reason why the extinction of the species in the wild occurred three centuries after the extinction of the aurochs, in 1919 [4]. We should not forget that the wisent survived the extinction in the wild only due to the fact that it was bred in captivity. Without the captive population, there would be no wisents today. The Caucasus wisent, B. b. caucasicus, did not have that luck and was fully exterminated in 1927.
Literature
[1] Lynch et al.: Where the wild things are: aurochs and cattle in England. 2008.
[2] van Vuure: Retracing the aurochs - history, morphology and ecology of an extinct wild ox. 2005.
[3] Bunzel-Drüke et al.: Praxisleitfaden für Ganzjahresbeweidung in Naturschutz und Landschaftsentwicklung – “Wilde Weiden”. 2008.
[4] Krasinska & Krasinski: Der Wisent: Bison bonasus. 2008.
I agree and the picture becomes even clearer when you add the third European bovine, the water buffalo, to the picture. The water buffaloes would have preferred fertile deltas and similar habitats, putting them in conflict with humans, who also prefer those habitats. Aurochs would have preferred lowland meadows and wood-pastures, putting them in conflict with domestic cattle and other livestock. Bison are more tolerant of upland and wooded habitats, and so they disappeared last. We see a near-identical pattern in Southeast Asia, where wild water buffalo are more threatened than banteng, which are in turn more threatened than gaur. Based on their ecological requirements, banteng and gaur could be considered tropical equivalents of aurochs and wisent respectively. Kouprey and Indian aurochs would also have inhabited the intermediate, lowland bovine niche, but the latter would have been additionally threatened by hybridization with domestic cattle and the former by a small original range, though of course it still didn't go extinct until quite recently. Why exactly wild Asian buffalo didn't go extinct entirely is unclear, especially since they would also have been threatened by hybridization with domestic buffalo.
ReplyDeleteIn Nepal and China one of the big problems for the wild yaks survival is that wild yak bulls become very aggressive and territorial in the reproduction period of the domestic yak cows chasing/attacking the farmers that can't approach the cows and produce milk. sometimes farmers kill the wild bulls. if something similar happened with wild auroch bulls this could be another reason...maybe they were killed by farmers to protect the cattle herds...
ReplyDelete
ReplyDeletePresumably miscegenation with domestic cattle played a role too. The recent blog discussing domestic cattle features in the last remaining Aurochsen reminds us of this.
Hybridization with domestic cattle altered the genetic structure of the last aurochs populations, but per se did not contribute to the decrease in number.
DeleteBut were the last animals actually aurochsen? A modern example of a species disappearing into a hybrid swarm is the possible future of Red Deer in Europe. In some counties of Ireland Red Deer genes in the wild are represented only in hybrids with the introduced Japanese Sika Deer. The same is slowly happening in Scotland.
DeleteThey were aurochs, but aurochs with domestic cattle introgression.
DeleteShouldn't one also take into account that contagious diseases were transmitted during contacts between domestic cattle and aurochs, against which there was no or too weak immunity in the wild animal population? That the spread of diseases was and is a concomitant of human migration is as well documented for early history as for colonial and neo-colonial dispersals (very clearly described in: Johannes Krause – Die Reise unserer Gene – ISBN 9783549100028). It stands to reason that domestic cattle also developed specific diseases early on due to the specific husbandry conditions and then carried these over long distances into local aurochs populations. Interestingly, with regard to the endangerment of the European wild cat by domestic cats, not only hybridisation but also the transmission of diseases is discussed among biologists (Yamaguchi et al. (2015),
ReplyDeletefile:///C:/Users/User/Downloads/10.2305_IUCN.UK.2015-2.RLTS.T60354712A50652361.en.pdf)
. It can be assumed that contact between domestic cattle and bison was less frequent and less intensive than with aurochs. This could have contributed to the earlier disappearance of the aurochs.
As far as I know, wisents are susceptible to most of the diseases transferred from cattle to aurochs too, so maybe this was not such a big factor why the wisent survived and aurochs did not.
DeleteYes, that is certainly true about the vulnerability of bison. But they are unlikely to have mated with domestic cattle brought by our ancestors from distant regions. As far as I know, there is no "natural" interbreeding between the two species. I am also not aware of such events in the Netherlands, where different cattle are kept together with bison in some projects. However, as you yourself have substantiated very well, there were historically crossings between aurochs and domestic cattle. For horses, too, you have described crossbreeding between wild and domesticated animals several times, supported by genetic findings. Perhaps these more intensive and specific contacts are a key to increased endangerment? But surely there were a majority of causes!
ReplyDeleteThe animals don't have to mate to transfer diseases. Bison in yellowstone get brucellosis from domestic cattle without mating. I think diseases played only a minor role why aurochs died out while the wisent survived.
DeleteYes, of course you are right! Also in Białowieża, identical infectious diseases were described for domestic cattle and for bison (Krasińska&Krasiński, Der Wisent, Neue Brehmbücherei) . Ticks, among other things, apparently play a major role in transmission. And: the bison would certainly only have survived the aurochs by the evolutionarily tiny period of 300 years if the same social conditions had prevailed in the 20th century as in 1627. In this respect, introduced cattle diseases could have contributed to population weakening in both species. The question should be: What chance do wild populations have of adapting to new pathogens from distant regions and climatic zones, and what conditions do they need to do so? The presumably very accelerated spread of pathogens through the migration of domestic animals could be of precarious importance here. There is some evidence that the contact of domestic cattle with aurochs - also due to mating - may have been more intensive than with bison. But you see: I'm getting bogged down in speculation! In any case, I find it very exciting that you are pursuing the question of concrete causes and conditions of the (near) extinction of the two wild cattle!
ReplyDelete