By Michael McCaskill
I’ve always been fascinated by badgers and their subterranean homes and as with many things, the more I learned the more my interest grew and grew. Naturally, this led to badgers being the focus of my Undergraduate research project whilst studying Applied Bioscience and Zoology at the University of the West of Scotland. Then, when I was accepted to study a Master of Research in Ecology and Environmental Biology at the University of Glasgow, I knew that my focus again, had to be on badgers. It was then through an introduction with Elaine Rainey, the project officer from Scottish Badgers, and Lesley Stewart, a Scottish Badgers volunteer, that I was introduced to the world of above ground badger nests.
What are above-ground nests?
As the name suggests, an above ground nest is a nest constructed by a badger above ground, rather than inside a sett. Although they can be called by many different names (such as day nests or couches) and can be found in a variety of places from hollow trees to under the cover of scrubland, they often share a similar structure of bedding in a cup shape, as can be seen above. As badgers are so well associated with their underground setts, it may be surprising that records of badgers making nests above ground in the U.K. go back as far as the early 20th century. These anecdotal reports often mention badgers sleeping above ground during the day, grooming near dusk and even nests containing very young cubs (Neal, 1987; Roper, 2010). Ernest Neal’s observations even led to him attempting to classify nest types in his 1987 book, the natural history of the badger (Christopher Helm Publishers Ltd), but despite there is very limited peer-reviewed research carried out relating to above ground nests. Even more, through my own research I found that the studies that have been carried out focus largely on the use of nests as diurnal resting places or in areas where the possibility of sett construction is less possible (Kowalczyk et al., 2004; Loureiro et al., 2007; Myslajek et al., 2012).
From this it was clear that a gap in knowledge existed surrounding how badgers made use of above ground nests, both for reasons other than daytime resting places and in areas with favourable conditions where setts are also readily available. I set project aims to attempt to bridge this gap and these included the following:
- When do badgers use above ground nests with regards to time of day and time of year?
- What are badgers using nests for?
What has been done so far?
To investigate the project aims set out, I joined Lesley in monitoring multiple nest locations which she had discovered in two sites in central Scotland. To do this we used camera trapping as way to view the badgers whilst they used the nests without disturbing them. By going through the footage collected, I have been gathering information relating to when the badgers are using the nests, as well as recording the behaviours of the badgers when they are in the nests. Other elements of the project have involved extensive survey work to identify further nest locations and other field signs with the help of classmates, Scottish Badgers volunteers and rangers from Scottish Wildlife Trust and the RSPB.
Observations so far
So far, I have analysed all camera footage from August to November and this has provided exciting early results. By carrying out analysis using linear models, I found that there was no significant change in nest use each month. However, a significant change in nest use did occur throughout the day with the probability of a badger using a nest significantly increasing from dusk before decreasing again as dawn approached, which can be seen in below.
During this largely nocturnal use, the nests were also found to support a variety of badger behaviours. In all four months, grooming was found to be the most common behaviour. However, resting, social interactions and territorial behaviours were also observed in all of the four months studied. Finally, mating was observed at low levels in both August and September. It was also found that badgers continuously maintained nest locations, in all four months analysed, which can also be seen below.
What could this mean?
These results provide new and exciting information as to how badgers are using above ground nests in Scotland. Firstly, the results indicate that badgers are significantly more likely to use the nest during the night, demonstrating that there is a gap in previous knowledge and research and more to nests than daytime resting places (indicating that ‘day nest’ may be a misnomer!). The analysis also found that there was no significant difference in nest use each month, which may indicate that nest use is constant during this period. Even the study period so far is interesting in itself, as it shows badgers are making use of the nest locations at a time of year where they traditionally expected to be moving towards winter torpor.
As mentioned, I found grooming and resting to be the most common behaviours expressed in nest locations, but important behaviours such as mating, territorial displays and social interactions were also observed. The occurrence of key life stages and important interactions in nest locations, could suggests that nests may play an important role in the organisation and continuation of a badger group and are not necessarily places for individual badgers to get away from the rest of the group. Secondly, badgers recorded rebuilding and maintaining nest also indicates that above-ground nests may be an important resource which badgers expend time and energy to maintain, much like setts.
The original project plan was to collect camera footage until the end of July this year to provide an insight and analysis of an entire year of nest use. Unfortunately, due to the lockdown and restrictions associated with COVID-19 it has not been possible to carry out monitoring since the end of march. However, all the data gathered up at this point will continue to be analysed to provide as complete a picture of nest use as possible. As well as this, I will also be continuing the other aspects of the project which include using proximity analysis and GIS mapping to hopefully provide greater understanding of the location of above ground nests and how this relates to their use, as well as exploring if temperature impacts when nests are used or not.
As so little is known about the extent to which badgers make use of above ground nests, the results of this research will hopefully provide a much greater understanding of important biological and ecological information. Understanding when and how nests are used by badgers could be of great importance to policy makers and for the conservation of this species. If above-ground nests appear to be a resource of greater importance than previously thought, it may be necessary to ensure that nests are afforded the appropriate level of protection. Furthermore, information in relation to the location and use of nests could be used to update best practice guidelines for carrying out protected species surveying for badgers; ensuring that current guidance is fit for purpose.
Although my project is far from over, I would like to thank all those who have helped out and been involved so far: Firstly, my university supervisor, Dr Stewart White, and all others from the University of Glasgow Institute of Biodiversity, Animal Health and Comparative Medicine who have offered me guidance and advice. Elaine Rainey, Lesley Stewart, and everyone else at the Scottish Badgers charity that have provided me with information and support; Clare Toner and the rest of the Scottish Wildlife Trust team at Falls of Clyde; David Anderson from the RSPB; and, everyone else who has volunteered to help with all the survey work. Thank you!