On Sunday the 25 April 1999 the two lambs were buried in shallow graves near a hedge where a fox was gaining access to the field as reported in CAScade #1. (see diagram below).
The site was inspected daily and at about 8 am on Tuesday 8 June (6 weeks and 2 days after the burial) the "Control" grave (ie the one where no red ochre was used) had been partially exhumed. I called upon the services of Mike Gambold, a well known local countryman and austringer (ie keeper of short winged hawks). Mike inspected the site and subsequently wrote: "...The point of ingress into the field was noted as was the trampled down path in the grass. At the site the digging was typical of a dog - like animal as opposed to a mustelid, (our only other large predator/scavenger, the European Badger - MELES MELES). A clear pad was discovered and photographed and verified by myself to be that of a Red Fox, VULPES VULPES. ...." The photograph shows Mike pointing to the foxes paw print.
The weather was sunny and I had covered the site with a polythene sheet for about 8 hours whilst waiting for Mike’s visit. This was probably a mistake and would have hastened decomposition. The fox had eaten most of the head leaving teeth and the lower left mandible. The lambs body remained in the ground and smelt a bit high. We covered it thoroughly with soil.
Three days later, on Friday 11 June the body had been dug up again and some more had been eaten. I could not see any footprints but took photos. This time I did not re-bury it.
There was evidence for a further five visits to the site. On the 19th June there were fox droppings near the grave which had been disturbed again. On the 20th the carcass had been taken out of the ground. Interestingly, two cleaned bones had been deposited beside the otherwise untouched grave of the lamb covered with red ochre. On the 21st the carcass had completely disappeared. On the 22nd there was fresh digging with clear sharp claw marks of a fox, presumably looking for any flesh left in the hole. There were inconclusive signs of a possible seventh visit on the 23rd. The stench of rotten flesh persisted at the site.
It is not unreasonable to conclude, from what is known of foxes’ habits, that the six or seven visits to the site were all made by the same fox or family of foxes. The visits spanned a period of more than two weeks, the fox’s path ran past the grave containing the red ochre covered lamb (see diagram) but no attempt was made during this period to rob this other grave.
However, on 25th June the red ochre grave was dug up and part of the corpse exposed. Interestingly, the grave had been attacked at two points, so there were two holes, one of which exposed the lamb whilst the other did not. Unfortunately, Mike Gambold could not inspect the site until the 26th and then he could not say for sure whether or not a fox was the culprit again. On the 27th the carcass had disappeared from view but there was no indication of any further digging. This grave was then covered with soil. To date (15 July 1999) there has been no further sign of digging. I cannot be sure that any of the red ochre lamb remains in the ground without excavating the site which we do not want to do just yet, since a subsidiary objective of the experiment was to see how long it would take for the bones to be stained red.
Making the not unreasonable assumption that all of the visits were made by the same fox or family of foxes, two conclusions may be drawn. Firstly, the fox dug up the control lamb in preference to that covered in red ochre, even though its path took it past the red ochre grave. The likelihood of this happening by chance would, all things being equal be 1 in 2 or 50%.
Secondly, the pattern of the two grave raids was different. The differences (two attempted points of access to the red ochre corpse and fewer, if any returns to the site) are not inconsistent with the hypothesis that red ochre affects the odour of the decaying corpse in some way. More light will be thrown on this aspect when the grave is excavated in a few weeks time - if any of the red ochre corpse remains, then the differences will be extremely significant. These differences, taken together with the route of the fox, indicate that there could be something causing the red ochre to discourage certain scavengers .
I have so far been unable to find out what that causal link might be. What is the affect of red ochre (an impure form of Ferric Oxide**) on corpses and foxes, etc.? If anybody has any ideas please let us know.
Indicated Further work
As well as finishing this experiment by excavating the red ochre grave, I hope that Doug Gentles and Alf Webb will repeat the experiment next year but on a slightly larger scale. For example, if two control lambs and two red ochre lambs are buried, we might have a more meaningful result (if the two controls are raided in turn before the two red ochre graves, the odds are 1 in 6 against this happening by pure chance, all other things being equal). The experiment would have to be repeated many times before we could be confident, from a statistical point of view, that there was a definite causal link.
We would appreciate any comments or suggestions from readers.
** Since writing this article I have received the following information and suggestions from our Treasurer, Simon Rutherford:
"Red Ochre is one name for an impure form of hydrated Ferric Oxide, Fe2O3. (Ferric Oxide is also known as Iron II Oxide, Mars Red and Jeweller’s Rouge.) It has a melting point of 1565°C and a Specific Gravity of 5.24. It is chemically stable and non-poisonous, but is considered a potential nuisance dust when present in industrial locations. I understand it is also present in Sequestered Iron which is used to acidify soil by gardeners.
I suggest the following possible hypotheses for discouraging scavenging animals. This could be associated with its metallic taste and mildly acid and gritty nature, viz.;
Any other ideas?