Wild Steps in a semi-wild setting? Habitat selection and behavior of European bison reintroduced to an enclosure in an anthropogenic landscape.

Pil Birkefeldt Møller Pedersen,Joanna B Olsen,Jens-Christian Svenning,Brody Sandel,Elissa Z Cameron

doi:10.1371/journal.pone.0198308

Abstract

Recently, several wild or semi-wild herds of European bison have been reintroduced across Europe. It is essential for future successful bison reintroductions to know how the European bison use different habitats, which environmental parameters drive their habitat selection, and whether their habitat use and behavioural patterns in new reintroduction sites differ from habitats where European bison have been roaming freely for a long time. Here, we address these questions for a 40-ha enclosed site that has been inhabited by semi-free ranging European bison since 2012. The site, Vorup Meadows, is adjacent to the Gudenå river in Denmark and consists of human-modified riparian meadows. During 2013 we monitored the behavioural pattern and spatial use of the 11 bison present and in parallel carried out floristic analyses to assess habitat structure and food quality in the enclosure. We tested habitat use and selection against environmental parameters such as habitat characteristics, plant community traits, topography, and management area (release area vs. meadow area) using linear regression and spatial models. The bison herd had comparable diurnal activity patterns as observed in previous studies on free-roaming bison herds. Topography emerged as the main predictor of the frequency of occurrence in our spatial models, with high-lying drier areas being used more. Bison did not prefer open areas over areas with tree cover when accounting for habitat availability. However, they spent significantly more time in the release area, a former agricultural field with supplementary fodder, than expected from availability compared to the rest of the enclosure, a meadow with tree patches. We wish to increase awareness of possible long-term ethological effects of the release site and the management protocols accomplished here that might reduce the ecological impact by the bison in the target habitat, and thereby compromise or even oppose the conservation goals of the conservation efforts.

Highlights

Megaherbivores and other large herbivores are increasingly acknowledged for their importance in shaping ecosystems in terms of physical structure [1, 2], trophic structure [1, 3], vegetation composition and diversity [1, 4,5,6] and biochemistry [1, 7] through feeding behaviour and pressure, trampling activity, seed dispersal, droppings and eventually as carcasses
The diurnal behaviour pattern showed that the bison herd had three major feeding bouts a day, namely during 4.30–8.30, 11–15 and 17–23 hours, with feeding bouts defined as periods with 15 minute intervals where more than 50% of the observations over the study period were feeding observations
Overall the present study found similar daily and seasonal behavioural patterns and habitat selection of a semi-free-ranging bison herd as seen in studies on free-living herds, despite the small living space and confinement and a high degree of human modification

Summary

Introduction

Megaherbivores and other large herbivores are increasingly acknowledged for their importance in shaping ecosystems in terms of physical structure [1, 2], trophic structure [1, 3], vegetation composition and diversity [1, 4,5,6] and biochemistry [1, 7] through feeding behaviour and pressure, trampling activity, seed dispersal, droppings and eventually as carcasses. Bison schoetensacki was present in Western Europe until the Upper Pleistocene and is thought to be a sister species to the modern European bison, Bison bonasus [12], which emerged in southern Caucasus after the Last Glacial Maximum (22kya) [13] and inhabited northern Germany and southern Scandinavia approximately 10kya [14]. The decline of Bison bonasus is thought to be caused by hunting [13] and increasing intensification of agriculture leading to habitat destruction and fragmentation forcing the escaping bison into the forest of Eastern Europe [13]. After World War I, a breeding program was initiated in 1920ies based on 12 individuals out of the 54 individuals surviving in zoos across Europe [13]

Methods

Results

Discussion

Conclusion