Bos bonasus, Linnaeus, 1758

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 577

4.

Wisent

Bos bonasus

French: Bison d'Europe / German: Wisent / Spanish: Bisonte europeo

Other common names: European Bison

Taxonomy. Bos bonasus Linnaeus, 1758 ,

Africa, Asia. Restricted by Lydekker in 1913 to “Bielowitza, Lithuanis” ( Poland, Bialowieza Forest).

Sometimes included in the genus Bison .

The pure form of the Caucasian Bison B. caucasicus 1s now extinct, but it is believed to persist genetically in a form crossed with bonasus , or the “Lowland Line.” It has been proposed that the extinct Wisent from the Carpathian Mountains and Transylvania was a distinct subspecies (hungarorum Kretzoi, 1946), but the evidence for it is equivocal. Another subspecies, montanus Rautian, Kalabushkin, and Nemtsev, 2000, has been described recently as a “ Highland Line” occurring in the highland forest belt of the Caucasus Mountains; the population on which itis based is actually descended from hybrids between Wisent and American Bison ( B. bison ) bred in the 1930s and introduced into the Caucasus Mountains. Neither subspecies is recognized here. Monotypic.

Distribution. C & E Europe and N Caucasus; became extinct in the wild and now scattered in free-ranging and semi-free populations in Poland, Lithuania, Belarus, Slovakia, Ukraine, and Russia.

Descriptive notes. Head—body 210-350 cm,tail 30-60 cm, shoulder height 150-200 cm; weight 350-1000 kg. Wisent is the largest ungulate in Europe. Closely resembling American Bison ( Bos bison ), Wisent have a dense, dark brown to golden-brown coat, with a tinge of plum coloration. The shoulder hump is pronounced, and the neck is short and thick, accentuated by long hairs forming a short beard or mane, often curly, on the underside—most developed in males. It has a curly mop of hair on the relatively flat and broad forehead and a short beard on its chin. The hindquarters are larger and less sloping than those of American Bison , and the Wisent tends to hold its head higher. The skull is broad and short, and both sexes have relatively long and slender black horns that project outward and then curve upward and slightly forward. In adult males, the horns may shred around the tips,like a Kouprey ( B. sauveli ) but less marked. A long tail drapes to the hocks or below. Dental formulais10/3,C0/1,P 3/3, M 3/3 (x2) = 32.

Habitat. Wisent use deciduous and mixed forests that optimally contain about 20% open glades, meadows, tree plantations less than ten years old, and recently cleared areas, all of which provide more abundant preferred forages such as grasses than closed forest. Coniferous forest is used secondarily, and a mosaic of forest types provides the most favorable habitat. In the Caucasus Mountains, Wisent use foothill forests in winter and move to subalpine meadows in summer. In Lithuania, Wisent use more open areas including agricultural fields. It is impossible to know if habitat preferences of Wisent now are comparable to their preferences when they were more widespread and abundant centuries ago.

Food and Feeding. Wisent are herbivorous, but they are known to consume more browse in forested habitats than their American counterpart. As a large bovid, daily forage requirements are high: 8 kg /day (less than one year of age), 19.5-28. 5 kg /day (2-3 year olds), and 23-32 kg/day (adults). In Bialowieza Primeval Forest, Poland, Wisent consume more than 130 plant species, including at least 96 herbaceous species (forbs), 14 grass/sedge species, and 27 shrub and tree species. Annually, grasses, sedges, and forbs make up about 67% of the diet; shrubs and trees make up about 33%. Important shrub and tree genera in the diet include Carpinus, Salix, Fraxinus, and Betula; important grass/sedge genera include Calamagrostis and Carex; important forb genera include Aegopodium, Urtica, Ranunculus, and Cirsium. Mast from trees can be seasonally important in forested habitats, and snow cover in winter can greatly affect diet composition. In less forested landscapes, and where agricultural fields are available, Wisent consume considerably more grass/sedge and herbaceous forage, particularly during the growing season; they revert back to diets higher in shrubs and trees when the growing season ends. In the Caucasus Mountains, Wisent move from the low-elevation forested habitats they occupy in winter to subalpine meadows in summer, and their diets contain more grass/ sedge and herbaceous forages. Many of the free-ranging and semi-free populations of Wisent are supplemented with hay in winter—a management practice that was implemented while reestablishing the species in the wild. Such supplemental feeding limits understanding of winter diets, movements, and natural mortality under wild conditions. Wisent do not necessarily drink free water daily during snow-free periods, but groups visit permanent water sources such as reservoirs and streams to drink. In winter, they consume snow, melted snow, and ice and will trod in frozen soggy soil to get free water.

Breeding. Generally, breeding and birthing seasons ofWisent are August—October and May-July, although some births can occur as late as October, depending on location. Some male Wisent stay with female herds throughout the year, but others, particularly mature males, live alone or in bachelor groups until rut. Physiologically, males can be sexually mature at about two or four years of age, but males 6—12 years old probably attain their maximum breeding performance and do not permit younger males to breed. As rut commences, males maintain a dominance hierarchy by fighting each other. After males reach about twelve years of age, spermatogenesis wanes. Males may live to about 20 years in captivity but only 14-16 years in the wild. Copulation is abrupt and of short duration. Females breed for the first time at three years of age and give birth in their fourth year. About one-half of the females in free-ranging populations in Poland and Belarus give birth every year. The reproductive life of female Wisent in free-ranging populations is 18-20 years, longer than that of males. Females may live up to 28 years in captivity, and one marked female lived to 24 years in the wild. Gestation is 254-279 days; sex ratio at birth is equal. Wisent have one calf at a time, very rarely twins and apparently only in captivity. Females leave their group to give birth; parturition takes about 90-130 minutes and occurs in a lying position. Neonates are 24-28 kg at birth. They stand 22-45 minutes after birth and begin suckling within their first hour of life. Females return to their group after a few days.

Activity patterns. Daily activity patterns are typical of ruminants involving alternating periods of foraging and ruminating/resting. Wisent often actively feed while moving from one location to another. During the plant-growing season, they spend about 60% of the day feeding, 30% resting, and 10% roaming without feeding. During winter, many populations are fed supplemental food, which influences the amount of time needed to acquire food; they may spend only 30% of their time feeding and 60% resting. In Bialowieza Forest, Poland, in late winter/early spring, Wisent may spend 18% of their feeding time stripping bark from trees.

Movements, Home range and Social organization. Wisent are non-migratory but may wander rather extensively in search of food and seem to use their habitats somewhat rotationally. In Bialowieza Primeval Forest, Poland, annual home range sizes of males increase with age from 44-136-5 km? (5-6 year olds) to 84:3-151-6 km? (older than six years). Home range size varies depending on habitats occupied. Maximum annual female home ranges are about 100 km?. Seasonal core areas in the overall home range are much smaller; in winter, male and female core areas are only 10-7 km?* and 7-9 km?, respectively, and the size is often constrained by snow cover and low temperatures or the availability of supplemental feed. When snow cover is light or absent, winter home ranges increase in size. During seasons other than winter, seasonal home ranges can be as large as 70 km?, but they may be focused on water sources and meadows. In Lithuania, annual home ranges may be as large as 200 km?* with core areas of about 20 km?®. Wisent are gregarious; group sizes vary depending on forage availability, time of year relative to breeding and parturition, and sex. Typical group sizes are 8-13 individuals, but groups of 20 or more individuals can be typical in open areas. Groups of about 100 individuals can be observed particularly in winter around supplemental feeling sites and in open settings with abundant forage. Groups are made up of females, their offspring, and young males, but they are not persistent family units, except a cow and her offspring of the year. Other individuals join and leave groups as they encounter one another, with young bulls changing groups most often. About 50% of mature males are solitary or they occur in small groups, typically of less than about ten individuals but often just two individuals. It is impossible to know if this grouping behavior was typical of the species centuries ago or is an artifact of conditions of reintroduction, limited numbers, and current habitat availability and fragmentation.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. The Wisent also is listed in Appendix III of the Bern Convention and Annexes II and IV of the EU Habitats and Species Directive. Historically it was distributed throughout Western, Central and South-eastern Europe, surviving up to 18" century in Germany, Romania and western Russia, until about 1790 in Hungary, and until early in the 20" century in Poland, with a closely related species (now extinct as a pure form) in the western Caucasus Mountains ( Armenia, Georgia, and Russia). A European Bison Pedigree Book is kept by the Mammal Institute of the Polish Academy of Sciences, which maintains records on genetic purity of individuals. Restoration of the Wisent after their extinction in the wild in 1919 is a testament to decades of efforts by many individuals, governmental and non-governmental agencies, academies, etc. From a founding population of only twelve captive pure Wisent, the total population of free-ranging Wisent in 2006 was about 1800 in 19 populations, with 1400 individuals more in captivity. Nevertheless, many challenges have been, and still are, encountered; lack of genetic diversity and inbreeding depression from the small number of founders, affecting skeletal growth; habitat degradation and fragmentation caused by a growing human population and its demands for agriculture and logging; diminishing places to restore populations; poaching; disease; and unintentional hybridization. Unfortunately, hybrids with American Bison occur too close to the Wisent in the Caucasus Mountains, Toksove Forest Park near Saint Petersburg, Russia, and Mordovia Wildlife Reserve. The 2004 Action Plan calls for continued captive breeding, establishment of a gene bank from semen collections, continued reintroductions with a goal of 3000 freeranging Wisent, management of existing free-ranging populations with the capacity of their habitat to sustain them, stricter control of poaching, and creation of an international breeding center. Captive populations exist in at least 30 countries worldwide.

Bibliography. Balciauskas (1999), Borowski & Kossak (1972), Cabon-Raczynska et al. (1987), Czykier et al. (1999), Dzieciolowski (1991), Gebczynska et al. (1991), Gill (1998), Huffman (2004b), Jaczewski (1958), Jedrzejewska et al. (1997), Kobrynczuk (1985), Krasinska & Krasinski (1995, 2002), Krasinska et al. (1987, 2000), Krasinski (1978), Krasinski & Raczynski (1967), Krasinski et al. (1999), Lydekker (1898, 1913), Nowak (1999), Okarma et al. (1995), Olech (1987, 1989, 2008), Pucek (1991, 2004), Pucek et al. (2002), Raczynski (1975, 1980), Rautian et al. (2000), Sipko, Abilov et al. (1993), Sipko, Rautian et al. (1995), Weigl (2005), Welz et al. (2005), Zorawski & Lipiec (1997), van Zyll de Jong (1986).

Figures

0. Yak (Bos mutus), 4. Wisent (Bos bonasus), 5. American Bison (Bos bison)

Distribution. C & E Europe and N Caucasus; became extinct in the wild and now scattered in free-ranging and semi-free populations in Poland , Lithuania , Belarus , Slovakia , Ukraine , and Russia .