Once again, things are busy at work, and I’ve been all over the country in the last couple of weeks, bringing business psychology to the masses and having little time for wildlife at home.
Today being Sunday though, I had time to get up early and go on my regular ‘dawn patrol’ walk around the fields and woods just as it is getting light. It’s a great time to be out watching wildlife, and as long as you don’t mind getting out of bed it gives you a whole extra part of the day.
7.00am found me sitting with my back to a tree, looking over a ploughed field. The usual gaggle of rabbits were out and about, a muntjac peered at me from the hedge, and a large flock of rooks was circling over the woods. As the light grew though, the main object of interest was a trio of Chinese Water Deer meandering around the field. Their tawny coats were surprisingly well camouflaged against the sandy soil.
Chinese Water Deer seem to be figuring in my thoughts a lot at the moment. They seem to be more numerous in the local area than I imagined. I think some of this has to do with my familiarity with them – a few years ago I would have classed all small deer as ‘muntjac’ and thought no more about it. Now I can recognise the CWD for what they are and distinguish them easily, and I smile at my past foolishness.
Unfortunately, when it comes to tracking, I’m still quite naive. I still tend to class all small deer tracks as ‘muntjac’ and think no more about it. In fact, I’m doing exactly what I used to do with visual sightings.
The problem is, the tracks of muntjac and CWD do look very similar. I could be looking at a field full of what I think are muntjac tracks, and they may actually be CWD. Or vice versa. For someone like me, who likes to be accurate, even on meaningless things, this is an important point.
The classic reference book of tracks, Animal Tracks and Signs, by Bang and Dahlstrom, doesn’t even mention CWD – I suppose they aren’t really common outside the Southeast of England (and China, of course).
The Hamlyn Guide to Animals – Tracks, Trails and Signs, my other preferred guidebook, says that CWD prints are very wide and splayed. The problem with this is, it’s wrong. The prints are actually quite small and neat. I know. I’ve spent the morning watching the deer and then walking up and looking at their tracks.
So, I’ve got a problem. It is difficult to tell the deer apart from their tracks alone.
The answer, I think, is to look at the trail as a whole, not at individual tracks. The trail of an animal is as characteristic as the shape of its feet. This is the approach recommended by Paul Rezendes in his book Tracking & The Art of Seeing.
This is where my tracking stick starts to come into its own. A tracking stick is a walking stick used in tracking. The main use of a tracking stick is to establish the stride length of a given animal, and knowing this, predict where the next track should be. The tracking stick helps you to narrow down the search area so you can find every single track. I tend to use my tracking stick as more of a simple measuring tool. I have marked it in 10cm intervals and it has a 10x1cm scale attached. This allows me to make rough and ready (but reasonably accurate) measurements in the field.
Here’s the clever part. Having come across a new set of tracks, I can measure the stride length. I did this for one trail, and found the strides to be 32cm to 38cm long, with most around the 36cm mark.
Looking at the guidebooks, they give a typical stride length for muntjac as 25-30cm, and for CWD as 30-40cm. This means that my deer, with a stride length of about 36cm, falls outside the range for muntjac, but well within the range for CWD. Based on stride length alone, we can say with some confidence that the trail has been made by a CWD rather than by a muntjac.
This is exciting stuff. Although I would struggle to differentiate between the two deer based only on the shape of their footprints, measuring and comparing stride length makes it quite easy to do.
As with anything, there are complications to using stride lengths and gait patterns to identify a species. Is the deer running or walking? Is it full size or half-grown? And so on. But I like it as a technique.
An awful lot of the information available about tracking today seems very ‘spiritual’ and mystical. I have no problem with this, and I respect anyone who can use it in this way, but it is not for me. I earn my bread and butter as a scientist, and although I like to get away from work as often as I can, I can never quite turn off my scientific reasoning.
This is why I like this measurement approach – it is scientific and can easily be applied and tested (unlike many ideas connected to tracking) and it appeals to my use of data and facts. I’ll see if I can make more use of it over the coming months.