Department of Physics, Chemistry and Biology (IFM)

Over the last decades, several wild populations of various species have declined. This is mainly a result of excessive hunting pressure (Brokordt et al., 2006) and habitat degradation (Griffen and Drake 2008). Reintroduction of animals is a way to save species from extinction and it may become an important tool for the management of wild populations and even species in the future (Griffin et al., 2000). Many of the reintroduction attempts, however, have not been successful in establishing viable populations (Snyder et al., 1996; Griffin et al., 2000), particularly when captive-bred animals have been used (Curio 1996; Mathews et al., 2005). Reintroductions from wild source populations have been more successful (Fischer and Lindenmayer 2000; McDougall et al., 2006; Seddon et al., 2007). Because of this, there are concerns that the individuals’ ability to survive in the wild is reduced in captivity (Seddon et al., 2007). It has been found that the success of captive breeding and release programs depends to a large extent upon the animals’ behavioural skills (Sutherland 1998). After several generations, captive animals often differ from their wild conspecifics, especially in respect to foraging, social behaviour (Snyder et al., 1996; Kelley et al., 2006) and anti-predator behaviour (Curio 1996; Snyder et al., 1996; Griffin et al., 2000; Griffin et al., 2001; Kelley et al., 2006). Many of these differences have been shown to have deleterious effects on fitness in the wild (Frankham 2008). Behaviours such as anti-predator response loose much of their adaptive significance in captivity and, therefore, both genetic and phenotypic variability for such traits are likely to increase (Price 1999).

The European bison (Bison bonasus), also known as the Wisent, have a well developed sense of smell, which it can use to detect predators (Nilsson 1847; Heck et al., 1920). Its sense of vision and hearing are less developed (Heck et al., 1920). This species is the largest mammal living in Europe . The males have a shoulder-height of to up to 2 meters and a body weight of up to 1000 kilograms (WAZA 2008). The European bison is classified as Vulnerable (VU) in the IUCN Red List of Threatened Species (IUCN 2009).

By the end of the 19^th century, only two populations of the European bison were left in the wild in two geographically distant regions. One lived in the Białowieża Forest in Poland and one in the West-Caucasus Mountains in Russia (Perzanowski and Kozak 1999; Akimov et al., 2001; Pucek et al., 2004 Mysterud et al., 2007). They belonged to two separate subspecies, the lowland wisent in Poland (B.b. bonasus) and the Caucasian wisent in Russia (B.b. caucasicus) (Pucek et al., 2004). During the turmoil following the First World War, the Białowieża Forest population became extinct in 1919, and in 1927 the Caucasian population was also exterminated (Perzanowski and Kozak 1999; Akimov et al., 2001; Pucek et al., 2004 Mysterud et al., 2007). At this time, there were 54 bison that had survived in a few zoological gardens.

The whole present-day population is derived from a founder population of 12 hybrid animals (B.b. bonasus × B.b. caucasicus) and a pure lowland line (B.b. bonasus) of only 7 founders. After World War I, the captive populations started to increase and in 1943 there were 160 animals. During the following years the population started to decrease again, mainly caused by the World War II. After the war, the population started to increase again and in 1952 the first animals were reintroduced into the wild in the Białowieża Forest in Poland (Pucek et al., 2004).

Today there are about 4000 European bison and approximately one third of them live in the Białowieża Forest in Poland and in Bieloweskaja Forest in Belarus . Controlled captive breeding is still very important for the continued conservation of the European bison. This serves to maintain as much as possible of the species genetic variation and reintroduction from these wild populations into the wild should be continued (Pucek et al., 2004).

The aim of this study was to investigate if captive-bred European bison would respond different to various stimuli depending on the enclosure characteristics they were kept in and if they would respond different depending on type of stimuli.

The hypotheses were that

• different groups of European bison would respond differently to the same stimulus due to their enclosure characteristics
• the European bison would respond differently to different types of stimuli
• the European bison would change their behaviour after having been exposed to a stimulus compared to a pre-test baseline