Thursday, October 3, 2013

Home on the range

Saving the European Bison

The European bison (Bison bonasus), also known as the wisent, is the largest herbivore in Europe. Historically, the Bison bonasus was distributed widely throughout Europe. At the end of the 19th century, the wild European bison (Bison bonasus) herds were reduced to two populations; Bialowieza Forest (B. b. bonasus) in Poland and in the western Caucasus Mountains (B. b. caucasicus)[LHN, 2012]. According to Pucek (2004), the initial decline of the wild bison was due to an over-population of deer species and drastic reductions of natural food sources. The onset of World War I and poaching were the final causes for extinction of the European Bison (Bison bonasus) in the wild. At the time of extinction of wild bison, the captive population consisted of 54 individuals (29 males and 24 females; with 12 founder animals)[LHN, 2012]. In 1923, Polish zoologist, J. Sztoleman introduced the idea of restoring wild populations of the European bison (Bison bonasus) from captive stocks housed in zoos. Later that year the International Society for Protection of European Bison (Bison bonasus) was founded in Germany (Pucek, 2004).

Bison restoration can be grouped into two main categories. The first is intensive captive breeding, followed by the creation of free-range herds. By the year 2000 there were 1700 free range animals and a total of 2900 individuals (Pucek, 2004). The European bison is currently listed as vulnerable on the IUCN Red list of Threatened Species (IUCN, 2012).

Summary of reintroduction programs
 The first reintroduction program of the European Bison (Bison bonasus) [from captive populations] began in 1952 (Pucek, 2004) in the Bialowieza Primeval forest (BPF) in Poland. Efforts resulted in the establishment of a single breeding population. Following this initial success, additional herds were established in other areas of Poland, Lithuania, Belarus, Ukraine, Russia & Kyrgyzstan; resulting in a total of 30 free ranging herds (Pucek, 2004).

Protection of genetic purity was aided by the European Bison Pedigree Book (EBPB) that had been created in 1932. All crossbred animals were eliminated from the breeding cycles of the pure genetic lines of bison. The EBPB is still in use today and every individual born worldwide is entered in the book. The reintroduction program began with intensive captive breeding programs in zoos and reserves from a founder stock of 12 individuals. Contemporary herds are now separated into two distinct genetic lines (Olech & Perzanowski, 2002). The second phase of the reintroduction began producing free ranging herds in natural habitat areas. The total global number of European bison (Bison bonasus) is approximately 2,900 (1,700 free or semi-free)[Pucek, 2004].

Since inception of the bison reintroduction program in 1952, staff at the BPF has been monitoring the free range bison populations (i.e. size, sex and age structure; recruitment; mortality)[Mysterud, et al. 2007]. Population dynamics analyzed by Mysterud, et al. on the BPF bison population [from data collected between 1952-2000] report that recruitment for the entire time frame yielded 741 males and 770 females resulting in nearly a 50:50 ratio. Analysis of the herd did not find any impact on recruitment pertaining to climate variations; however mortality rates were found to be higher in cold winters, as well as lowered reproduction rates (Mysterud, et al., 2007).

Habitat preservation is essential to the success of reintroduction of the European bison.  The BPF is one of the best   protected deciduous lowland forests in Europe (Mysterud, et al. 2007). Currently the bison are dispersed globally in 30 countries. Studies conducted by Kuemmerle, et al. (2011) indicate there is suitable widespread habitat that is currently unoccupied in Central and Eastern Europe. Viable population increases are not limited by habitat accessibility.


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Mysterud, A., Barton, K., Jedrzejewska, B., Kransinski, Z., Niedzialkowska, J.F., Kamler, J., Yoccoz, N. & Steneth, N., 2007. Population ecology and conservation of endangered megafauna: the case of European bison in Bialowieza Primevil Forest, Poland. Animal Conservation, 10. Pp-77-87. Online. Available through Wiley online. 

Olech, W. & Perzanowdki, K., 2002. A Genetic Background for reintroduction program of the European bison (Bison bonasus) in Carpathians. Biological Conservation, 108. Pp.221-228. Online. Available through Elsevier.

Pucek, Z., 2004. Status Survey and Conservation Plan: European Bison. IUCN/SSC Bison Specialist Group.  Online. Available at:

Tokarska, M., Kowalczyk, R., & Perzanowski, K., 2011. Genetic status of the European bison Bison bonasus after extinction in the wild and subsequent recovery. Mammal Review. V. 41, 2. Pp. 151–162. Online. Available through: Wiley Online.

Wolk, E. and Krasinska, M., 2004. Has the condition of the European Bison deteriorated over the last twenty years? Acta Theriologica. 49 (3). Pp. 405-418. Online. Available through Ebsco host.


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