Introduction
Human activity has resulted in the decline of mammalian carnivores. There is less support for the “meso-carnivores” like badgers than there is for the bigger species like cougars, bears and wolves. These smaller carnivore species have been persecuted heavily to the point of the existence of a conservation concern. They have not been studied as much as the bigger species and they are more seen as a “pest”.
Badgers are a good example for a “meso-carnivore” species as they are considered a pest by most landowners and are exterminated due to the risk that their burrows pose. Not just their extermination has resulted in the population decline but also the loss of their habitats and a decrease in prey are responsible.
The badger species found in British Columbia is a subspecies called Taxidea taxus jeffersonii and it is considered endangered. It is found in the Thompson and Okanagan regions which support a dry interior. Their preferred habitats are grasslands and open forests. The badger is one of the few grassland species that are critical to a naturally functioning grassland ecosystem. They play a big role in regulating semi-fossorial and fossorial prey and help with the soil conditions like aeration and nutrient mixing by digging. Their burrows are used as protection by many other species such a the black widow spiders, snakes and tiger salamanders. They are an endangered species in British Columbia with only about 250 adult badgers left. The animal’s ecology is poorly understood in British Columbia. The research that was conducted in six American states does not show the same conditions as in British Columbia and therefore can’t be used for this region. There have only been two researches on badgers in British Columbia so far that have identified knowledge gaps regarding spatial ecology and habitat selection.
Background of the project
In this thesis it was important to gain more knowledge of the ecology of badgers in the Thompson region in British Columbia and support their conservation. The objectives were to identify the patterns of spatial use and the burrow site selection.
Methods, Materials and Study Area
4,390 km2 were covered by the study area around Kamloops especially in the dry valley bottoms. The North and South Thompson river valleys dominate the landscape. The rich soil of the Thompson region grassland results in a high agricultural capability which makes the area for suitable badger habitat smaller.
One of the methods to study the ecology of a species is to determine the size, location and shape of the animals home ranges. Home ranges usually encompass the resources that they need for feeding, mating and rearing offspring. Gaining knowledge of not only the location but the intensity of use can help determine source and location of important resources for the animal. Core areas are within the home ranges and used more frequently. To determine the core areas they have to be used more often than expected and they should be of importance to the species in question, which would be the badger in this project. As a field method badgers were live-trapped, brought to a vet and fitted with a intraperitoneal radiotransmitter. To determine home range use fixed kernel density estimates were used. To determine the core areas a method was used that tests for non-random use of the home range.
The trappings were also used to determine the habitat selection of the badgers. To assess the selection more the burrow locations were examined to identify resources nearby. Data on habitat features, prey availability and soil characteristics were collected at random locations and burrows for every individual badger. The habitats were divided into eight classes. The habitats were compared at burrows within core areas to burrows outside core areas. The soil characteristics reflect the ability of badgers to dig in certain areas. Prey availability was assessed by identifying potential food items and from evidence of badger diet.
Results of the Study
14 badgers were trapped and tracked within three years. They were all male except for one adult female and her female kit. It was not the intention to primarily trap males. Between 2 and 51 locations were collected from each badger. During the summers a total of 207 locations were collected, during the winters only 61. They moved around more during the summer than during the winter. Regarding home ranges, the male species in the northern parts had the biggest ranges and the female had the smallest range. Four of all the tracked animals used their core areas throughout the whole year. The number of core areas used was 1 to 5. 104 burrows were examined. Out of those, 24 burrows were weren’t used often and 80 burrows were used extensively. The ones that were used heavily were located inside core areas the other 24 were outside of such areas. Burrows were situated both in natural habitats and ones that were altered by humans.
Discussion
Individual badgers used their home areas differently, however, they generally inhabited large areas and were able to move longer distances than reported in studies outside of British Columbia. The large variations in home range use for each badger might be related to limited resources and therefore it is critical to understand and acknowledge these individual variations to set management strategies.
Badgers in areas that were altered by people were very tolerant of human activity. The favoured habitats were grasslands and moderately altered areas dominated by grass. Areas that were avoided were riverbanks, harvested sites and forested areas. There was no strong selection for any soil variables tested but badgers appeared to be more in areas that had an abundance in prey. The highway mortality of badgers is a big concern for the badger populations. So are habitat loss, hunting, trapping and prey extermination.
Suggested Action
For the future it is important to determine the role of female badgers in the spatial ecology since they might be a factor male badgers orient themselves on when setting up their home range boundaries. Furthermore, it is critical to investigate the influence of prey on the spatial ecology and habitat use in the future. The last important step is to create a badger habitat capability model that includes finer-scale requirements like prey resources.
Conclusion
It was the aim to gain more knowledge about badger ecology in British Columbia to address conservation initiatives. The focus lay on research on spatial ecology and habitat selection. It was determined that the badgers used large home ranges, were tolerant of human disturbance, were not restricted to one particular habitat and that the spatial use was determined by the orientation of resources which explained the use of core areas by individuals.
- Source Corinna Sara Hoodicoff. April 2003. Ecology of the Badger (Taxidea taxus jeffersonii) in the Thompson Region of British Columbia : Implications for Conservation. Available at : http://www.badgers.bc.ca/pubs/Hoodicoff_thesis.pdf [Accessed 03/2021].