The impact of disturbance on red deer

Student Spotlight - Eilidh Smith

PhD Research at Durham University

Email: eilidh.m.smith2@durham.ac.uk  Twitter: @eilidh_mws

Background

Hillwalking has become increasingly popular in recent years, and Scotland is no exception. However, increased recreational activity in the hills can lead to disturbance of wildlife such as red deer (Cervus elaphus), altering their spatial distribution and behaviour, and can also lead to conflicts between different land users. This is significant due to the ecological and economic importance of deer. In my PhD I aim to quantify and assess the impact of disturbance on red deer by hillwalkers on a mountainous estate in Perthshire, Scotland.

Fieldwork

The biggest and most challenging component of this project so far is the fieldwork. My data collection focuses on the distribution and movement of red deer, and their behaviour in terms of vigilance and response to disturbance events, all in relation to hillwalker activity. In addition to this, I have also been tagging calves to increase the numbers of marked individuals in the study site so I can track individual movement and begin to assess if disturbance could be affecting the survival rate of calves.

Herd counts and transects

Wherever I go in the study site, and whatever I’m doing, I record deer sightings. I collect information on the number of animals in the group, the type of group, the location, current behaviour, and as much demographic information that I can. I also record when I’ve looked in a particular area and haven’t seen any deer.

In addition to opportunistic herd counts, 4 times a month over 2 weeks, I walk the hillwalker’s path as a transect and record deer sightings and deer absences. I aim to do this twice during the week as a proxy for a ‘quiet’ day in terms of visitor numbers, and twice on weekend (’busy’) days. My route is about 18 km and includes the 4 Munros (mountains > 3000 ft/914.4 m) in the study site. It’s a long day, starting about 9am and often finishing around 8pm. I take my time and check each area along the way thoroughly for deer.

Transect days are probably my favourite data collection days, however the weather can make them extremely challenging, particularly if areas are filled with fog or the wind and rain are making it impossible to see anything. Several times I’ve had to abandon transect day halfway through and try again another day due to not being able to see enough of the study site.

Camera trapping

I currently have 22 camera traps deployed across the study site to monitor deer activity and allow comparisons with a previous study in the area (carried out by PhD student Solene Marion, University of St Andrews). Checking and servicing camera traps is a great job for days when visibility is too poor to observe deer, or if I’m lucky enough to be experiencing continuous good weather, I work camera checks into transect and behavioural observation days.

Behavioural observations

Disturbance responses can be dramatic and empty an entire hillside of deer, but they can also be more subtle, in the form of increased vigilance. My behavioural observations involve sitting and scanning groups of deer every 3 minutes to record behaviour, in particular head position, which indicates vigilance level. To avoid disturbing the deer myself, I am either positioned at a discreet distance, or take great care to approach unnoticed. When conditions are favourable, behavioural observations can be very relaxing – often in quiet parts of the study site and away from people, it’s just me and the deer. Other times it’s cold and uncomfortable, and occasionally I am of course joined by hordes of midges.

Deer spend most of their time eating or resting/digesting, but watching them just hang out being deer is fascinating. I like it when their behaviour tells me there are people on the hillwalker path before I’ve seen or heard anything, and by sitting watching them for long periods I’m also able to fill in some of the gaps in their movement patterns left by my snap-shot herd counts and camera trap photos.

Calf capture

Calf tagging in such a large area is a big challenge, but it’s a really rewarding bit of fieldwork. Red deer calves go into hiding while the mother moves off to graze and shift predator focus away from the vicinity of the calf. These calves are really hard to spot if you don’t already know where they are (and sometimes even when you do!), so calf capture focuses around watching deer from a distance until they reveal the locations of their calves. I then keep a close eye on it and watch the spot where it goes down.

Once found, the calf is relatively easy to ‘capture’. If young enough, it will simply lie there and hope that you don’t spot it. If the calf is a bit older though, some extra stealth is required, though sometimes even this isn’t enough.

Next steps

Collaring

This project also aims to obtain more detailed, continuous data on deer movement and behaviour using GPS collars fitted to adult females. Like most things in the mountains, adult capture provides its own set of challenges. Timing is critical, the deer must be darted when they do not have calves that are highly dependent on them, but also not immediately after they’ve conceived, or whilst heavily pregnant. Conditions need to be cool enough so that the deer does not over-heat while anaesthetised, but as the weather gets colder the movements of the deer become less predictable and they are found in larger groups that are harder to sneak up on. To dart a deer we need to be within 40 m – to put that into perspective, during deer management activity, deer stalkers/hunters need to be around 100-200 m from the deer to take their shot.

Collaring efforts will re-commence later this year, and will continue until early Spring next year unless we reach our target number of animals before that.

Acknowledgements

Massive thanks to my supervisors Prof. Phil Stephens and Dr. Sean Twiss (Durham University), to North Chesthill Estate for their continued support, and to the wider advisory team of Dr Scott Newey (James Hutton Institute), Dr Urska Demsar (University of St Andrews), and Dr Althea Davies (University of St Andrews). In addition, special thanks to Dr Neil Anderson and Gidona Goodman (University of Edinburgh) for lending their support and expertise to our collaring efforts.

Social media

Follow me on Twitter (@eilidh_mws) for “Deer diary: short stories from the field”.