By Lindsay Waddell
Friday, 18 May 2012
The escalation of an outbreak of mycoplasma spells trouble for red grouse
A couple of years ago, things were looking brighter for moorland keepers with the advent of a new generation of medicated grit. It was thought that, thanks to this grit, there would be no more large-scale population crashes due to worms. Around the same time, I heard a nasty rumour on the moorland telegraph that mycoplasma had been found in grouse on a moor in the Pennines. This was far from good news. Just when we thought we had overcome one problem, here was another — this one potentially far worse, from what I had heard from the low-ground men.
Two seasons on, things have deteriorated somewhat. There are now at least five moors where mycoplasma has been found in varying numbers, from a couple to almost 100. So, where has it come from?
I am indebted to Mark Elliot MRCVS, a member of the National Gamekeepers’ Organisation’s deer department, for taking the time to discuss the subject with me, and if there are any errors in what I am about to tell you, then I am sure it is my fault rather than Mark’s.
Mycoplasma is like many other diseases and viruses that afflict wildlife, in that it is mainly species-specific. There are 136 known forms of mycoplasma, and most of them are only found in certain types or species of birds. The theory that the grouse strain has come from crows or starlings is wrong, as the strains those two birds carry would not transfer to red grouse. So, if it has not come from those two, how could it have arrived on the moors? It is possible it may have come from wading birds, such as the odd migrating redleg partridge, but until we find out what strain it is, we will not know the likely original host. That is, of course, if it is a strain that has been identified before, but it could be a new strain.
An untreatable patient
Red grouse are unlike many gamebirds in that it is almost impossible to treat them for any disease. Living most of the time on open moorland with lots of water, a food supply and heather, it is also impossible to add anything to either that would help them rid themselves of the disease. Finding a way to administer treatment was a problem that we also had to overcome with the strongyle worm, but eventually treated grit was developed. I fear that the scenario with mycoplasma will be far more problematic.
Almost everybody I have spoken to regarding this issue suggested population density as a possible reason for the outbreak; however, there is actually no connection to numbers. That may be a good thing; it may not — if density were to blame, it would mean we could do something about it. The moors concerned have a wide variation of grouse numbers, with one moor where a couple of birds were shot only just being able to crop a few birds last year.
One cause for optimism is the fact that this virus has only ever been shown to transmit itself from one generation to the other via eggs in domestic poultry — it has never been shown to do so in partridges or pheasants, for example, so it may be that this outbreak will run its course in the red grouse without doing lasting harm to wide-scale populations. We can but hope that that is indeed the case. Only time will tell, but it is a rather worrying time.
Rain, rain, go away
To those of you who have been praying for rain, or doing anything else to encourage it, could I please ask you to reverse the process, or simply to keep it specific to your own patch, as we have more than enough of the stuff following day after day of rainfall.
The dry weather that preceded the current wet spell is a double-edged sword on moorland at this time of year. If it is dry, birds of all species will build their nests in any suitable spot, with little regard for water. If it then pours down and floods the dry peat — which, as any gardener will tell you, is pretty impervious when dry — you quite quickly get large areas of standing water, which, in turn, wash out many nests. I have had reports of some nests being found, and there will have been many more that have not been seen.
The poor waders suffer equally badly in the wetter fields, with large pools forming and simply forcing hens to abandon their nests. In a strange way, the higher, wetter moorland, with its covering of sphagnum moss, may fare slightly better, as the moss soaks up large quantities of water before flooding becomes widespread, and the birds up there may well pick a slightly better site in the first place. I hope they do. Our season depends upon the weather turning for the better, and soon.
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