Birth control measures for Wensleydale grey squirrels. How will this effect predating raptors like Goshawk?

Goshawk-predating-grey-webGrey squirrels in North Yorkshire are being given contraceptives in their food in a bid to control their population. The move is being made in Wensleydale to help the red squirrels which live there thrive. The red squirrel has been in severe decline in the UK as the greys, which are not a native species, increase. It is believed that greys act as carriers of squirrel pox – which kills reds.

Great, but has anyone in charge of this project given any thought of how the chemicals used in the contraceptive once ingested by the Grey Squirrel will then affect raptors like the Goshawk? As we know the Goshawk regularly predates grey squirrels, also feeding them to their offspring in the nest? This is perhaps a step too far, how can this be justified if the use of these contraceptives then proves down the line to be detrimental to the well-being of protected species like the Goshawk, or for that matter other raptor species like the Buzzard and Red Kite? Research has shown Goshawks predate between 75% to 95% grey Squirrel.

We strongly suggest before this ill thought out trial proceeds, more research and consideration is given into the wider consequences upon other forms of wildlife, in particular birds of prey. Perhaps instead of raising our concerns here, both Natural England and RSPB should be raising this issue with appropriate agencies?

This reminds us of what has been taking place of red grouse moors, where gamekeepers are using chemicals to control a harmful parasite worm (trichostrungylus Pergracilus), which can harm the gut of the grouse. We are advised there are no controls on the use of chemicals to treat this infestation which are mixed with grit placed in trays strategically spaced across the moors. The grit mixed with chemicals are then eaten by the  grouse to help digest their food, young heather shoots.

Has anyone given any real thought to how these chemicals go on to affect the health of people who eat red grouse?



7 comments to Birth control measures for Wensleydale grey squirrels. How will this effect predating raptors like Goshawk?

  • Les Wallace

    Try getting a gamekeeper to say that the return of the pine marten is a good thing for the red squirrel – they are pretty good at eating grey ones – and see where that gets you? Like getting blood out of a stone. Funny that re establishing pine marten in the Wensleydale area wasn’t raised, at one stroke two native species are helped for good as long as habitat isn’t defiled or martens slaughtered. An absolute fortune must have been spent on trying to control grey squirrels what an utter waste of time, energy and money. This contraception will have to be constant, even if local greys die out surrounding population would move back in. Of course the role the goshawk has in reducing grey squirrel population is probably an even more taboo subject than bringing back martens.

  • Editor, your last sentence ”Has anyone given any real thought to how these chemicals go on to affect the health of people who eat red grouse”?

    Surely this is just the tip of the iceberg regarding human health? Everything that we consume has either been manipulated or contaminated with either insecticides, antibiotics, growth hormones, other toxic/harmful chemicals, radiation, etc.
    A couple of good examples relate to the poultry and salmon farming industries. Totally scary and disgusting what we and the general population are being served up and even worse is the barbaric conditions that these creatures live out their lives.

  • Trapit

    I don’t like the idea of yet more chemicals let loose on the countryside.
    However,it would be nice if something could be proved to act specifically on Grey squirrels,and not carry on up, or even down(via scavengers)the food chain.
    I am obviously concerned for Red Squirrels,but more so for the future of woodlands in this country.
    The hardwood forests of the next century,will look very different from those of today, unless we do something fast.
    I cannot speak for Pine marten ,but we have more Goshawk than you can shake a stick at, and I am afraid they have no effect on grey Squirrel whatsoever.

  • Thorbjorn Odinsberg

    I think that Trapit has the right of it here Goshawk diet in some sites may contain high proportions of squirrels but that is the wrong way to look at it. What needs to be considered is what proportion of the squirrel population is taken, that is probably quite low. It is basic ecology the predator has generally little effect on the long term breeding population of the prey. Yes Pine Martins will reduce grey squirrels, reaching a new prey/ predator balance because the Marten is currently absent but there will still be Grey Squirrels sadly.
    I believe the chemical has been tested, (it has to be for approval) and thus is unlikely to cause predators or scavengers a problem.

  • AlanTwo

    I think it is naïve in the extreme to think that because a chemical has been tested as part of the approval process that it will not have damaging effects on non-target species.
    The history of the last 50 years is littered with examples where precisely the opposite has proved to be the case.

  • Thorbjorn Odinsberg

    As somebody involved in this sort of testing although not this particular chemical, much of that testing involves the effects on non targets. the naivety is all yours if you think otherwise.

  • AlanTwo

    I didn’t say that such testing was not performed, just that unintended consequences affecting non-target species have occurred repeatedly.
    Or are your claiming they haven’t?