Guest blog by Kerry Metcalfe
Researching the effect of human activity on badgers in Dalby Forest, UK
European Badgers (Meles meles) are an instantly recognisable species and much more common than you might think; estimates suggest the population in England and Wales is around 485,000 (Judge et al., 2017). Yet badgers are rarely seen beyond a flash of black and white, or as roadside casualties.
After spending a year discovering the joy that is badger watching (find suspected badger sett, don warm clothes, sit quietly binocular-distance away from badger sett, wait patiently as darkness looms, hope for badgers!) I became fascinated by this intriguing yet elusive species, so when it came to developing a research project for my PGCert in Ecological Survey Techniques, it was an easy choice.
Badgers emerging from their sett.
Research location and aim
I arranged to carry out my project in Dalby Forest, a large forest located in North Yorkshire and managed by the Forestry Commission. Dalby is a publicly accessible and offers a variety of recreational activities, in particular many miles of cycling and walking trails; there are a number of farms located within and around the forest, and the forest itself is largely plantation and used commercially for timber. It’s also one of the forests covered by NatureSpy’s Yorkshire Pine Marten Project. I decided to find out how Dalby’s badgers were influenced by such variable, widespread human activity.
In the UK, badgers have no natural predators and are protected from persecution and sett disturbance by the Protection of Badgers Act 1992, however studies show that badgers fear people and change their behaviour in response to human voices and disturbance (Clinchy et al., 2016; Sadlier and Montgomery, 2004). Specifically then, I wanted to find out if different levels of human activity influenced sett status and size, and badger emergence time i.e., the time they first leave their setts on an evening.
Lots (and lots) of badger setts!
I was provided with the rough locations of 90 setts discovered by forestry staff during the preceding 18 years, and my plan was to resurvey these setts to check for activity (was the sett active or inactive), and size (how many entrances does it have), and then select 10 setts that I could camera trap to gather data on emergence times. The latter part was dependent on loaning some trail cameras and a friend suggested I try NatureSpy, so I sent a message explaining my project and to my delight was offered 10 cameras for loan. An educational morning was spent with Ed from NatureSpy who showed me how to set a couple of cameras up, then I was off on my own. I’d chosen 5 setts in high human activity areas, and 5 in low human activity areas so that emergence times at each could be compared, and it took me just over a day to set all the cameras up due to access to some of the setts being very remote. Choosing the right sett entrance was really important because if I focused on the wrong one I might not see any activity, or could miss the initial emergence, so I’d planned in a contingency week for making adjustments before data collection began. Luckily the cameras are really easy to install, so where I needed to switch to a new entrance it was easily done.
A badger sett chosen to be monitored with camera traps.
Fast forward through several months of fieldwork, camera checking and setting up complex maps in specialist QGIS mapping software and I had my data. It sounds simple but in reality I spent many hours picking my way through vegetation looking for badger field signs to locate existing and new setts (there’s a good reason the best time for badger surveys is winter), photographing latrines, removing ticks from myself, and repositioning trail cameras after they’d had encounters with badgers and a very feisty teenage bird of prey.
A Browning camera trap in place to monitor a badger sett.
Interpreting how human activity influences badger behaviours
I think my results were a surprise to all involved. In total I found 174 setts, 106 of which were active, and recorded well over 3,000 20-second clips on the cameras – far more data than I’d ever imagined collecting.
Statistical analysis on sett status and size found that neither are influenced by different levels of human activity. This suggests that badgers in Dalby occupy and desert setts for other reasons. Analysis on camera trapped data was a slightly different story. Setts from high/low human activity areas were split into similar pairs and analysed, and one pair showed a significant different in emergence time – specifically, badgers in the sett located in a low human activity area emerged significantly earlier than those in the corresponding high activity sett. Sounds simple enough and I could assume that this equated to a fear of humans, but in reality there were a few other factors to consider.
Badger paw print.
So why don’t Dalby’s badgers seem too perturbed by people and what does influence sett status and size? Well, badgers are nocturnal, so unlike species that are active during the day, they’re protected temporally because very few people (author aside) are tempted to go wandering in a forest at night. They’re also fossorial – they live underground – and setts can have many metres of tunnels and chambers, so they’re protected spatially too. They’re also adept at choosing inaccessible (to people) locations to dig their setts, so that’s a three-fold layer of protection from human activity.
A badger sett entrance.
Sett location is generally driven by suitable habitat and access to resources (food, water), and this is likely to be a major factor in an existing sett being active or not, and in how large a sett gets – if food resources run out or the area becomes unfavourable, relocation is preferable; if the area remains favourable, they stay and expand the sett as necessary [this is a very, very simplistic way of stating something that’s rather more complex and has been the subject of various theories and research for many years!]. In Dalby, suitable habitat tends to be relatively high up steep valley slopes with a large degree of tree cover. The human activity affecting most of these setts was mountain biking (Dalby has many miles of mtb trails), and whilst trails were frequently in use through the day, activity was fleeting – most cyclists pass by within a few seconds – so actual disturbance of sleeping badgers in underground setts was likely very low.
A badger grooming not long after emerging from the sett.
Emergence-wise, high human activity may influence the time that badgers were emerging from their setts, but in other studies where fear of people was a factor, badgers were observed delaying emergence time to dusk (Tuyttens et al., 2001). In contrast, badgers at my significant setts emerged well before dark. I’m very guarded about my significant result because it’s a small data set and it’s likely that other factors, for example the presence of cubs, the size of the group, use of alternate entrances etc contributed towards differing emergence time. In particular, other studies have found that cubs spend significant amounts of time around sett entrances (Cresswell and Harris, 1988a), so this could be a major player in my results. Cub activity certainly affected my footage – I recorded an average of 504 20-second captures of badger at setts with cubs vs 164 at those without.