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Badgers bridge territorial borders

A clearer understanding of badgers' territorial habits give vital clues to the likely effectiveness of badger culls. By introducing different technology to collect tracking data, an interdisciplinary team from Oxford and Cambridge has gleaned important new insights into badgers’ potential interactions.

Strategies for the culling of badgers to help prevent the spread of bovine tuberculosis are typically based on assumptions that badgers mainly move within certain territorial borders. Growing evidence, however, suggests that European badgers may socialise more with other social groups than previously thought.

To demonstrate that is the case, it is important to be able to track where badgers are relative to each other, and how often they are in the same place at the same time (or a different time). This pinpoints the occasions when badgers may transmit disease, directly or indirectly, among themselves.

When aiming to build a continuous picture of the infrequent interactions of badgers, all previously used technologies have had various disadvantages, as well as certain merits. Deficits that hampered analysis included, for example, tag battery life being too short, the difficulty in measuring individual badgers' positions at specific points in time, and data security issues.

In a 13-week proof of concept study a research team set out to test a fully automated active RFID (aRFID) system to better measure badgers' movements. Our computer scientists teamed up with zoology experts from Oxford’s Wildlife Conservation Research Unit and Cambridge to fit badgers with 20g aRFID tags, and set up wirelessly networked base stations in setts and near latrines.

For the task, researchers from the Department of Computer Science (led by Professors Niki Trigoni and Andrew Markham) adapted commercially-available technology, which has usually been used by the security industry to protect high value assets in small areas, such as valuable paintings.

The study demonstrated that the aRFID system could collect data on the location of individual badgers when they were within 31.5m of base stations (which could then be used to show when badgers were in the same place at the same time). It also showed that the system was capable of operating continuously over a long period, with the tags predicted to last between two to five years. By storing data off the tag, it could be accessed remotely, and data security was high.

The study also showed that this niche aRFID technology is highly suited to this sort of tracking and analysis. It has an advantage over other technologies because of tag longevity and because it allows infrequent events to be detected in small defined areas, which we can achieve by restricting the detection range. The wireless interconnectivity of base stations also means it could potentially be accessed from anywhere in the world.

The data collected enabled researchers to track how much time badgers spent within their own social groups, and with other groups, at setts and latrines. It showed that of the time spent by badgers mixing together, they were for the most part with members of their own social groups in their own setts. This was as expected, but proved that analysis of aRFID data can corroborate known location patterns.

Further analysis threw up new findings about badgers' habits: around 16% of the time when badgers were near each other was spent mixing with other social groups near latrines and at setts. In each week of the study some badgers visited others' setts. The analysis suggested that badgers regularly go beyond their own territorial borders, which contradicts previous assumptions, and puts into question conventional strategies for badger culling.

A research article about the findings of the study was published in Methods in Ecology and Evolution:

This article first appeared in the Winter 2017 issue of Inspired Research.