Last year, we carried out some badger territory mapping surveys at a site near Northampton. I took the opportunity to use a trailcam to record the badgers on the site in order to illustrate the behaviours which underlie the technique. Along with some footage of us putting out the bait and carrying out the latrine checks, I have mocked up a hypothetical site to show how the technique allows the territories to be mapped – I hope you find it interesting!
Badgers are social creatures and form social groups which typically include a main sett, a number of secondary setts (including annexes, subsidiaries and outliers) and foraging habitat. The collection of secondary setts and the key foraging areas are critical to the functioning of the social group and need to be protected when developments and changes in land use are proposed. On some sites therefore it can be valuable to understand where the territories lie. For example, if you were studying a site where a road was proposed nearby, you would want to know whether it was being routed between a social group’s sett and their foraging habitat as this would lead to a risk of mortality if they continue to access their foraging grounds across a new busy road.
Two social groups may be situated in close proximity and untangling the use of a site by one or more social groups can be a tricky business. This is where the technique of territory mapping comes into play. It is made possible by the fact that badgers have well established ‘latrine’ sites where they deposit their faeces. These latrines can be found throughout their territory but are especially pronounced at the peripheries, as they are used to mark their territory boundaries. Taking advantage of these latrine sites, the territory mapping (or bait marking) technique involves feeding badgers with a bait which contains small, inert, plastic beads of different colours. The beads are small and harmless – they pass straight through the badgers’ digestive system without any risk of harm to the animals. The bait is placed at the main sett locations and a different coloured bead is used at each sett. We can be fairly confident that only the badgers which are associated with a main sett will eat the bait placed beside it, and therefore deposit the beads along with their faeces in the latrines within their territories. We place the bait – a mix of peanuts, peanut butter and golden syrup – at the main setts for 1-2 weeks, and then monitor the latrines to see which colour beads turn up in which latrines.
Each time a bead is found in a latrine, it is recorded on the map. Over the course of the surveys, this map builds to show the territory of the badger social groups.
For more technical information on how to go about badger territory mapping, there is a Scottish Natural Heritage (SNH) guidance note which you can read here and a scientific study from Delahay et al (2000) which you can read here.
We carried out this survey at the Ecological Consultancy I work for – the example territories and mapping in the video are just a randomly selected area of countryside rather than a site we were commissioned to survey. If you have a site where territory mapping is required, please get in touch with me!