Friday, 24 September 2010

Messing with predators

What's a mesopredator? When I first heard the word, I thought it referred to something prehistoric, maybe T Rex's baby brother. But no, it turns out to be a predator that's not quite at the top of the food chain. Right at the top you have the apex predators such as wolves, bears, tigers and the like. Below them come the mesopredators - feral cats, mink, maybe even... buzzards?

I've been reading a fascinating paper published in the journal Bioscience. It's called The Rise of the Mesopredator. You can download the pdf here, but there's a summary of the main points here.

The basic message is you mess with predators at your peril. Things aren't as simple as that neat pyramid they used to teach at school: predators eat herbivores eat grass.

Sometimes big predators eat smaller predators; there are omnivores that cross boundaries; animals adapt to a shortage of one prey species by eating another; and so on. Which will come as no surprise to most readers of this blog, of course: shooters and keepers see this sort of thing every day.

One of the paper's main points is that apex predators keep the numbers of smaller predators (mesopredators) in check. And when humans remove an apex predator - as they do, because wolves kill livestock etc - then the mesopredators run out of control, and they don't neatly limit their own numbers to suit the availability of prey.

This has a disastrous effect on all kinds of species further down the chain - things like songbirds, for instance.

Fascinating stuff, and perhaps a good argument for reintroducing sea eagles, wolves and bears to Scotland if you're that way inclined. (Incidentally it looks as if Alladale may have shelved its plans to reintroduce wolves).

Or another way of looking at it... Having cleared out the apex predators from the UK years ago, humans have been battling to control mesopredators ever since. When a mesopredator's numbers spiral out of control, it's important to take action to protect biodiversity. Not pass ever stricter laws to make the mesopredator untouchable. Er, buzzards anyone? Badgers?

--

And yes, I know this will rattle a few cages. But is there any real science to show the effect of buzzard numbers on biodiversity? I suspect that's one research project the RSPB won't be funding.

42 comments:

PBurns said...

Here a post from the U.S. that might be of interest: "Cowbirds, Mesopredators, & Grass Nesting Birds : at >> http://terriermandotcom.blogspot.com/2006/03/cow-birds-hay-fields-and-grass-nesting.html

P

Meconopsis said...

Whilst sitting at a good vantage point on the wild farm I look after the other day I noticed 11 buzzards circling in the sky's above a goshawk one of a breeding pair that the birdie folk have not found yet and a wee merlin. Below and within 30 yards was one of 6 badger sets. The normal crows and rooks were in every field. Not 300 yards away sits a wood that stinks in the winter due to the thousands of crows etc that roost there each night.

Other wildlife ? not much to be honest.

To think that the owner used to have trailing spaniels and hosted a 2 day open trial 20 years ago is a sad thought indeed.

It is a wildlife wilderness and until the predators go nothing will ever change. Shame on the RSPB etc.

Murphyfish said...

Hello James,
Just a thought, so we've cleared the apex predators from our little isle and now the Mesopredators are running riot. But if we rid our isle of these what then will fill the niche, after all nature does seem to have a habit of filling the holes we make. If only apex predators didn't eat us poor humans reintroduction would not seem to bad an idea after all. Just a thought....
Regards,
John

Meconopsis said...

As I thought 10 hours and none of the normal anon or RSPB folk have replied. Lets be honest the RSPB folk that look in this blog are brainwashed town dwellers who in reality don't have a Scooby's about real life wildlife and its management.

I having been born in the soil do and I love wildlife I love to get out and see wild birds on the farm for free, Would I pay to go to an RSPB Zoo ? no way.

Will we stand by and let livestock be killed ?

You have to look at the fines work out the cost and do as nature tells you to have any wild birds or even a few rabbits nowadays!

James Marchington said...

Hi John / Murphyfish,
I dont' think anyone is suggesting we should exterminate every mesopredator, even if that was possible (we haven't done a very good job with mink and foxes, now, have we?)
But if buzzards or badgers or whatever are harming biodiversity, it would be mad not even to have the discussion about how to mitigate that - whether by finding ways of keeping them away from vulnerable species at important times (like nesting), or by careful localised culling.
Is a gamekeeper an apex predator? Discuss.
James

vicky said...

We can a) bring back the apex predators and cull some humans to restore natural order or b) allow certain humans to control the mesopredators (note; control does not mean wipe out). We may have made some mistakes in our ascent to ultimate top predator but running away and hoping mother nature can sort it our just won't work!

Sooty said...

Hi Meconopsis I find my problem is I see valid points from all sides and strange just like about 60 million others there are some things I think need controlling and others I am O K with but we all seem to have differing opinions about which ones.The only one I find I cannot see valid points from is Anon but then they just seem intent on proving time after time there superiority and listening to how clever there comments are.

Meconopsis said...

Is a gamekeeper an apex predator?

If he is a good keeper he most certainly is !

A good keeper will be happy to live with wildlife as keepers are quite lazy folk :-) as long as the birds are ok they can get on with the veg garden and training dogs etc.

However if a problem arises they somewhat like a hungry raptor wake up and take action.

Badgers killing lambs ? Cormorants killing the lairds trout in the pond !

Problem sorted like a Raptor full of meat the Keeper goes back to their sedate way of life.

Murphyfish said...

James,
Not to sure that I can answer your points or for that matter add to the discussion. As I’m not usually a serious writer or commentator and tend to err upon the lighter things on my attempt at a blog, but here goes:-
Possibly part of the problem is that we, as a race, interfere to much with our own concepts or visions of what is a healthy, rich in biodiversity environment, and as our race continues to expand pressures on resources and living space will throw up more conflicts of interest. It will be interesting to see whose ‘vested interests’ will eventually shape the world we live in. Perhaps of tangent slightly, I guess I’m just trying to say that we all have a different outlook/opinion on what a healthy, rich in biodiversity environment, depending upon our livelihood, needs, where we live, even daresay our morals etc.
I notice you mention the mink, one of many specious that could be held up of our own self indulgence of what our countryside should house, pheasant, carp, grey squirrel and a mired of plant life to name some examples, although the mink only ‘naturalised’ I guess due to some mis-informed idiots in balaclavas. I suppose that we all have different views of how to control nature but in reality whatever we attempt will always be wrong for some reason or other, perhaps the only true way to control nature is to give it it’s head on a planet where humans cease to exist.
As for the gamekeeper being an apex predator? In this country the majority of humans could be classed as such, but take away the veneer of civilisation and it would be interesting to see who could feed themselves with their present knowledge levels, not too many I warrant. But a gamekeeper? Yes with his or her knowledge of nature I’m pretty much sure that not only would they survive but that they’d be top dog in their locality, but in today’s scheme of things I kind of have the impression that it’s not the gamekeeper who’s top dog but rather the decision makers and back hander’s in the room at the top.
So not to sure if this has added or not, just a ramble I guess.
Best regards,
John

alan tilmouth said...

Meconopsis "real life wildlife and its management" real wildlife shouldn't need managing.

James - "buzzards and badgers harming biodiversity" - they aren't though both may have an impact on profits of farmers/game businesses in different ways.

Two points from the report you cited in this post

1. "Several factors indicate that such management can be
problematic. Overabundant mesopredators are often resilient
to control programs because they are characterized by high
densities, high rates of recruitment, and high rates of dispersal
(Palomares et al. 1995). Lethal control can thus be likened to
mowing a lawn, in that persecution induces vigorous growth
in the mesopredator population"

2. "Coexistence with predators
requires humans to be willing and able to modify their own
behavior."

It could be argued that Buzzards are actually Apex predators and therefore the recent return to a healthy population level is to be welcomed in terms of reducing the populations of Rabbit, Rat etc.

James Marchington said...

Alan, are you deliberately missing the point? Yes, I fear that buzzards and badgers are both harming biodiversity - but I don't have the research data to prove it one way or the other, and neither I suspect do the RSPB or anyone else. Are they even going to ask the question, or do the three wise monkeys thing, like they do with magpies and pet cats? Our wildlife is too precious to trust to a politicised organisation like the RSPB. How about a National Audit Office for wildlife to see through the spin that's put on it by NGOs of all flavours?

And seriously, 'real wildlife shouldn't need managing'?? What planet are you living on. Mine has humans on it - perhaps the answer is we ship them all off to the moon and leave the wildlife to look after itself?

alan tilmouth said...

James, let's expand this Buzzards, Badgers and Biodiversity theme, please outline the wildlife you think is being impacted by a healthy population of Buzzards and the problem with the current population of Badgers. (Obviously you will need to exclude managed game birds such as Pheasant & RLP and any arguments about bovine TB as Cows aren't 'wildlife' or biodiversity).

James Marchington said...

Alan as you're well aware I don't do scientific research, so you'll have to look elsewhere if you want chapter and verse. Our 'healthy' population of buzzards is definitely impacting birds such as the lapwing, however, and badger groups privately admit that badgers are playing a significant part in the massive decline of hedgehogs. Of course RSPB/RSPCA are in denial about all this, and blame intensification of farming, habitat loss, etc, etc. Which is why some independent research would be a breath of fresh air.

alan tilmouth said...

In 100 years of publishing notes and studies including the results of a 30 year study of breeding Buzzards at Sedburgh (1937-1967)in the esteemed journal British Birds I cannot find a single reference to Common Buzzard either preying on Lapwing or evidence of Lapwing remains in Buzzard pellets.
Lapwing is not listed as a prey item in Birds of the Western Palearctic the definitive source of information on bird species ocurring here. I would add that in 21 years birding in Northumberland I have never seen a Lapwing taken by a Buzzard (Sparrowhawk -yes). Please help me out here and let me know how you are 'definite' that they are impacting the Lapwing.

James Marchington said...

Well there you have it, if the esteemed journal British Birds doesn't mention it, it doesn't exist. I'll tell the lapwing chicks not to worry then.

vicky said...

Alan, does a buzzard have to kill an animal or bird to cause it's decline? Disturbance of ground nesting birds could lead to brood failure without the buzzard ever eating one...couldn't it? I have seen small domestic pets die because large birds, foxes or cats have entered their garden and scared them to death though they never tried to eat the animals-different scenario but it's food for thought.

The thing is that the RSPB needs to take the FEARS of farmers, gamekeepers, pigeon keepers etc into account. Their fears MAY be unfounded but presenting high quality research in as format they can understand is the way forward. Using the RSPB's deep purse to fund projects that HELP these parties protect their hobby, livelihood or less photogenic ild birld species AND allow for healthy raptor numbers is he way forward- not simply rubbishing their fears and berating them at every turn.

Meconopsis said...

Eagle Owls. The RSPB say they love em but info from the dark internet world says they hate them. Whom do you trust ?

Best go with the old man called common sense I know lots of people think he is dead but out here in the Scottish countryside he is alive.

alan tilmouth said...

James, so basically you choose to ignore the science and evidence from a 30 year study to hang on to your belief that Buzzards are 'definitely' having an impact on Lapwings? This wouldn't be because it dismembers the argument that Buzzards need to be controlled for anything reason other than the profits of the shooting and game industry?
Vicky, whilst I can see why you might perceive that Lapwings and other ground-nesting species are perfectly evolved to avoid detection from predators, that's why they've survived this long. Unfortunately they haven't had time to evolve to cope with the massive changes in farming practice over the last 50 years, the real cause of their decline.

James Marchington said...

Alan, you seem determined to be confrontational over this, and cannot see past your entrenched belief that the 'shooting industry' is all about greed and bloodlust. Why don't you go and find a shoot near you, join the beating line, and find out what shooters are really like. There's no future in simply slagging off people for what you think they are.

alan tilmouth said...

What I'm determined to confront is opinion that misleads people into believing that a species like Buzzard is 'bad for biodiversity' which was the inference in this post. I'm also determined not to be sidetracked, so please acknowledge the points I've made. A 30 year study (would you like a copy) of Buzzards breeding in Sedburgh Cumbria did not note Lapwing as a prey item. There are no scientific references to Buzzards preying on Lapwing in the species literature, plenty of other species mentioned but not Lapwing so please rather than trying to suggest I'm being confrontational address the opinion you raised and back up your belief or acknowledge it was erroneous.

alan tilmouth said...

Also please note 'greed and bloodlust' are your words not words I've used. I maintain the opinion that profit (different from greed) motivates the rhetoric against raptors. I'm yet to see anything that dissuades me of this. I'm in the field almost every day, I may not be shooting or beating but I am observing.

James Marchington said...

There's rhetoric on all sides. What we need are facts, proper research, without spin this way or that. Trouble is, too many organisations depend on the spin for their livelihood.
I hear reports almost daily of the problems on land adjoining RSPB managed reserves. I will be visiting such a place in the next couple of months and hope to report it in the mag - but such is the fear that speaking out against RSPB will have have repercussions on stewardship payments, that landowners are reluctant to be identified.
I have eyewitness accounts of buzzards taking lapwing chicks, from people who I have promised not to identify.
I've nothing against buzzards, lovely birds, what I can't abide is this attitude that they are somehow incapable of ever being a problem.
All I ask is that people keep an open mind.

Sooty said...

Alan you seem scientific so please explain these massive changes in farming practice which affects lapwings so much.

alan tilmouth said...

Sooty, I'm not a scientist but the changes that have had an impact on Lapwing (and other farmland species) in no particular order are
a) a massive shift from spring to winter sown cereals reducing the availability of suitable nest sites and summer food.
b) an increased use of pesticides and subsequent reduction of summer food supply.There is a secondary impact here increased spraying can result in increased nest destruction and chick mortality.
c) an increase in the amount of arable farming reducing pasture and impacting upon food supply.

The reduction in available nesting habitat can also result in an increase in predation. As nests get concentrated in available habitat these concentrations attract the attention of predators. With Lapwing these will be predominantly mammalian such as badger/hedgehog/fox/stoat/rat.

I'd just add for the sake of clarity I have not said that Buzzards don't take Lapwing just that the literature doesn't highlight this so Lapwing is not a frequent prey item. I'm sure that Buzzards as opportunistic predators do take the odd one but to suggest that this may be behind the Lapwing's decline is nonsense. The studies I have mentioned in earlier comments over 30 years were not by the RSPB and were published in an independent journal (British Birds).

James Marchington said...

The study mentioned ended when I was 10. A lot has happened since then. Not least that I now regularly see buzzards in SE England. Farming has changed enormously too - not just the rise of pesticides but a swing away from some of the more harmful types. I recall watching hares dying after crossing fields sprayed with Gramoxone, now banned. It's too simplistic to blame 'intensification' - farming is continuously evolving in response to market pressures. Changes inevitably alter available habitat, and affect 'wild' (not really wild is it?) populations. Do we freeze farming in time? Push it back a few decades? More? Can we do so and still feed ourselves? And they think Child Benefit was a difficult decision!

alan tilmouth said...

DeFRA's own report on food security stated "UK agricultural land could provide more than enough food from arable production in terms of our daily calorific requirements in theory making the UK self sufficient"

Farming is indeed as you have rightly highlighted driven by market pressures, the problem being that the market doesn't recognise the inherent value of wildlife. It doesn't take it onto account on the balance sheet.

James, you said 'changes inevitably alter habitat' but why must those changes always degrade rather than improve? Why are they at the expense of our wildlife?

I didn't 'blame intensification' I set out the reasons as asked for in relation to changes in farming and the impact on one species of farmland bird (there are many others that have been impacted in many ways)

It is possible to achieve a balance, at a cost, one that we, that's you and me, need to be prepared to pay for at the supermarket tills. Look at what is being achieved with Higher Level Stewardship.

In relation to Buzzards and your 'a lot has happened since 1967' comment answer me this, Rabbits and Rodents form the main part of Buzzard diet (fact but I don't have time to cite all the references), has the increase in Buzzard population resulted in a 60% decline in Rabbits or Rats? If not why not surely Buzzards haven't suddenly after thousand of years of evolution switched to feeding exclusively on Lapwing in the last 30 years despite an abundance of their main food sources?

As for child benefit I have four kids I don't earn £43k these days but if I did I would gladly give it up to ensure my kids and their kids could still hear the Corn Bunting and see the Lapwing.

Sooty said...

Alan most of the changes you say in farming would have not made the big difference you say but how about more corvids now looking for easy chicks as less estates trap them.Corvids in my opinion are becoming serious threat,or more likely already are and yet you do not even mention them or have you not seen lapwings desperately trying to protect their chicks from crows,even spring watch showed a little plovers nest destroyed by jackdaw oh but that is nature they say,rubbish when numbers get out of control.

James Marchington said...

Alan I don't think the savings on Child Benefit will be spent on the environment - more's the pity perhaps, but until buzzards get the vote humans will always jump the queue in government priorities. All this 'letter to the future' stuff is all very well, but when the chips are down people want to be safe and comfortable, and sod the corn buntings. Sad perhaps, but humans are human. Paradoxically, shooters are one group who put more back than they take out. A statement that I don't expect you to take at face value, but one that I believe is true.

alan tilmouth said...

Sooty, please support your assertion that changes in farming are not behind the decline in Lapwings with something other than an opinion. Pretty much all of the changes and impacts I outlined are set out in various independent scientific studies over recent years.
How can you so blindly and easily dismiss them?
Corvids like many other species prey on other species as well as eating grain, worms and spending time at landfills they are opportunistic. You make the mistake of using typically emotive language 'desperately''destroyed' to me is all a bit WI. Yes, it is nature and yes sometimes hard to watch but it is what it is.
Perhaps as expected I disagree that corvids are out of control, they have now reached population levels that are less controlled by man than in recent times in some areas. Now that Lapwings are at the low levels they are at increased populations of corvids are probably putting additional pressure on them but that isn't how the Lapwing got into the state it is now in.

alan tilmouth said...

James, I noticed you avoided making any comment about Buzzards and the Rabbit population, has this debate opened your mind to how unlikely it is that Buzzards are now or have ever played a part in the downward trend in Lapwing populations?

James Marchington said...

Alan what is it with this point scoring? A predator could eat toffee apples 98% of the time, but if that 2% is a vulnerable species at a critical time, it will have an effect. Viz foxes and breeding tern colonies. Which proves nothing, except that we should keep our minds open. See cognitive dissonance here.

Sooty said...

Alan as a retired farmer I can tell you farmers have not seen these changes to the extent that you seem to have seen.Because you have flimsy scientific evidence you jump on the oldest bandwagon in the world not knowing anything else to say that increased intensive agriculture to blame.This has been going on for centuries oh and for sure science can prove anything.For instance half scientists think badger culling will solve the problem half think it a bad idea.Do not know if you saw it and I did not make a note of it but there was a article about something that was happening in France was the biggest problem for lapwings.As a direct contradiction of your argument about winter cereals to blame I have seen lots of lapwing nests in winter cereals and indeed it could be argued it gives them better cover but then what do those of us on the ground every day know compared general public and scientists with a given agenda

alan tilmouth said...

James I'm not point scoring, I am simply astonished that you can claim to have an open mind and then state as you did that 'Buzzards are definitely affecting birds such as the Lapwing' without a shred of evidence other than some eye-witness accounts that a Buzzard may have taken the odd one somewhere in the UK. Most of us that are in the field regularly can relate similar eye witness stories of various raptors catching various prey but this does not form scientific evidence that they are therefore responsible for a decline in that particular species population. Most species have annual attrition rates varying from 20-70%; some of these losses occur from predation.

James Marchington said...

OK, I believe that buzzards are definitely affecting birds such as the lapwing, but I am prepared to be proved wrong. How's that?

I should think it's highly unlikely that any single factor is solely responsible for decline of lapwings or any other species.

Oh, apart from gamekeepers, who are of course solely responsible for the parlous state of the UK hen harrier population. Ahem.

alan tilmouth said...

Sooty, whilst I didn't post references for all the studies from which my comments were drawn ( I will if needs be) please explain why what I've suggested is based on flimsy evidence. Had you read the studies on Lapwing decline you would not be referring to flimsy evidence? Unless of course you simply wish to deny the truth as someone with a vested interest ( I don't have one by the way hopefully that allows me to be objective).
With regard to France you are probably referring to the trapping of Lapwings in great numbers each year to be eaten as a delicacy under the well used argument that it is traditional. Of course James will be supportive of the French right to hunt and trap, regardless of the further impact on declining Lapwing numbers.
As for your comments on winter cereals go and read the studies (example: http://pdfserve.informaworld.com/340245__909088751.pdf) this is one of many that highlight the issue.

James Marchington said...

http://ec.europa.eu/environment/nature/conservation/wildbirds/hunting/docs/Lapwing%20EU_MP.pdf - an interesting overview of the problems facing the lapwing, and some valid action points based on facts not bigotry.

Alan, what on earth makes you think I would support hunting/trapping of a threatened species at unsustainable levels? Your view of shooting seems to be based on watching an Elmer Fudd cartoon. Since you're so fond of research, go do some before coming on here slinging mud.

alan tilmouth said...

James, I've found some interesting material tonight whilst searching far and wide for any Buzzard study that included Lapwing as a prey item. Turns out that during a comparative study of two separate populations in Scotland, one whose avian prey was predominantly large e.g woodpigeon and pheasant and another where the avian prey was small i.e Meadow Pipit and thrush species, the first population had a sustained bigger clutch size.
So perhaps the reason behind the increase in Buzzard numbers is down to you and your mates releasing more and more Pheasants to shoot ensuring a steady higher calibre food supply and therefore increased clutch sizes. The irony I'm sure wont be lost on you, the solution to reducing Buzzard numbers is glaringly obvious, stop releasing Pheasants and reduce the number of rough shoots. This would potentially reduce clutch sizes and legally control the population without killing a single raptor.

James Marchington said...

The irony here is that when it suits you, buzzard predation can impact a species' population; when it dosn't suit you, it can't.

alan tilmouth said...

James, I haven't mentioned shooting in any of my comments. I though we were discussing Buzzards and the statement you made that they were definitely affecting Lapwing populations.
My opinion that you would support the French right to hunt & trap Lapwing was formed through reading your blog over several months, if it was incorrect I accept that.
As far as your final comment is concerned you may wish to read my last comment again as I did not make any mention of Buzzard having an impact on any species population.
It's obvious to me that you (and Sooty) are not willing to look at the science, you have made no attempt to argue on the basis of the information provided and continue to ignore the reasonable and valid arguments put forward in favour of limited anecdotal 'eye witness' accounts and unsubstantiated opinion. You criticise the RSPB for producing propaganda against gamekeepers yet you have done exactly the same here. You have made unsubstantiated claims about Buzzards that encourage gamekeepers and shooters to believe they are responsible for the decline in Lapwing (they aren't)or that they are a meso-predator (they aren't)and therefore need controlling.
My only agenda is the protection of all birds, I'm not anti-shooting I'm anti the illegal killing of birds of prey; I'm not anti-farming but I am against the 'profit at any costs' mentality that appears to dominate.
As for the suggestion of bigotry, I don't think the conclusions I've drawn from the available scientific studies are 'beliefs' so I'm at a loss to understand why you would resort to name calling other than to distract away from an argument you appear to have lost.

James Marchington said...

"you and your mates releasing more and more pheasants to shoot" sounds like a mention of shooting to me, but perhaps I misunderstood you there.

I prefer to think of science as a never-ending search for truth and understanding, rather than a blunt instrument with which to 'win' arguments.

I think you're onto a hiding to nothing with your mission to "protect all birds", since encouraging one species must have a detrimental effect on another, which was kind of my point.

Still, I'm with you on opposing illegal killing, so we do have some common ground.

alan tilmouth said...

I wish I could leave this I really do... but.. to be pedantic you will note that the single use of the word 'shoot' was made in a comment that came after you made reference to 'my view of shooting coming from an Elmer Fudd cartoon' therefore as I previously stated when I responded to that remark I had made no reference to shooting in any previous comments so why comment on my 'view of shooting' at all?
I agree that science is the search for truth, the point of all this being that the science regarding Buzzards and Lapwings does not support the version of the truth you were promoting. There is no link between an increase in Buzzards and the decrease in Lapwings. Obviously you may choose to highlight that perhaps we have yet to discover such a link. Please refer back to comment 8 of mine in relation to the rabbit and rat populations and the increase of Buzzards and feel free to offer a plausible explanation why the population of these two species that form the highest percentage of Buzzard diet here in the UK have not also declined. Whilst my comments about an increase in rough shooting and Pheasant releases were slightly tongue in cheek, there is as I suggested some evidence to suggest that this may in part have fuelled the increase in Buzzards in some areas through bigger clutch sizes of Buzzards catching bigger prey (i.e Pheasants). Whilst I'm not advocating any sort of ban at all on Pheasant shooting as I'm well aware of the benefits to many other species through habitat creation, supplementary winter food etc perhaps the industry has to accept that an increase in Buzzards is a consequence of releasing millions of non-native species into the environment annually for sport.

James Marchington said...

I expect the RSPB will be acknowledging shooting's contribution to buzzards very soon - a major media campaign at the very least.

I think the rat/rabbit/lapwing thing is the same as the harrier story - if something is already in dire straits, then losing a relatively small number is a bigger deal.