Sunday, 29 April 2012

Neoichnology: Tracking big red ruminants

Some things send a real shiver down your spine, and for me one of these is being unexpectedly confronted with wild animals. Some years ago my wife and I were our walking in the hills near our home when we had a close encounter we've never forgotten. Our route took us past an old quarry, basically a platform delved into the hillside for the purpose of extracting the carboniferous gritstone used to pave the streets of the local towns and villages. I fancied a quick look at the exposures that were still visible despite the quarry floor having been reclaimed by nature. As we turned into the quarry we came face-to-face with a large Red Deer stag. The stag had heard us before we'd even seen it, and the movement of it looking up caught out eye. We stood a few feet away from this magnificent animal before it turned and disappeared into the scrub, leaving us with a sense of elation.

Great Britain's largest native mammal, Red Deer (Cervas elaphus) are present throughout most of Britain having migrated here around 11,000 years ago, although according to the British Deer Society website some populations represent feral animals rather than descendants of native animals. As we have extirpated all keystone predators from these islands Red Deer are thriving at present and indeed culling is necessary to ensure populations are kept in check.

Red Deer stag bellowing. You wouldn't want to bump in to this chap during the rut.
Picture by Bill Ebbesen and used under CC licence (Wikipedia).

Our local Red Deer herd spend most of their time in the surrounding hills (the area was part of a royal hunting forest) where they can be spotted grazing in fields in groups, often of over 30 individuals. They descend to lower elevation during the night and  some mornings it's possible to walk through the long grass and see where each deer spent the night. It was in the hope they had been around recently that I went looking for tracks with the intention of recording them using photogrammetry; I discussed the Mallard tracks I found during this same trip in my last post.

I was lucky this time and found and recorded two the two tracks presented here. They were both found at a small ford on a stream that runs down the hillside. This area is frequently trampled by the local dairy herd who use the ford for crossing a field boundary and drinking but as they are still inside at present the only tracks on the mud surrounding the ford were of deer and the paw prints of a small dog (the area is heavily frequented by dog walkers). The individuals that left these tracks are both relatively small, and might possibly have been left by a hind and juvenile, possibly one of last year's calves. Due to the lack of heavy trampling it seems only a few animals passed this way rather than a large group.

The first image is the smaller of the tracks. I've rendered both untextured and textured versions of each track recorded to demonstrate the morphology of the track and quality of the mesh. It has to be said that these are rather large files, and could probably be decimated without detrimental loss of information.

Red Deer track, untextured mesh. Notice organic detritus and grass blades, which have
gaps underneath where data was not recorded. Lots of detail of in this (large) mesh.

Textured version of the same print with exactly the same lighting settings.

The other track showing the mesh and track morphology.

The full render of the other track, same lighting settings as the untextured version immediately above.

As can been seen in the two sets of images above, the meshes generated by the photogrammetry software are very detailed and very accurate, capturing sub-millimetre detail. The gaps in the mesh tend to be where overhangs occur, for instance under blades of grass or underneath overhanging areas of displaced substrate. Stone and organic detritus are very well represented.

These images further demonstrate the quality of data that can be captured using photogrammetrical techniques. Hopefully there will be much more of this to come in the future!


  1. ah, Stu, we will have a field day (three in fact) if you really show up at DigitalFossil 2012!