Uk Peregrine Population Limit? (1 Viewer)

[Anthony Morton]

Thankyou, 'pianoman', that's exactly the question I'm looking for an answer to. /QUOTE]



thought the question you were seeking an answer to was the one posed by CM.

A question which has been answered by those who've chosen to, to the best of their ability.

Is that it?

'Strewth, you've got a long memory LB!

 

[Edward woodwood]

As an ecologist i learned....

Predator-prey cycles are potentially unstable; predators often kill all their prey in a lab setting, for example.

In nature, stability and coexistence are likely to persist due to spatial heterogeneity in the environment (differences over area etc)
Prey at low levels can persist (some prey not being found or whatever) and then increase later as predator declines.
Prey can evolve to reduce their vulnerability.
And once a prey population has reached very low levels, predators can prey on different prey species, allowing the original to increase again.

In theory, that's it.

 

[CBB]

And what, may I ask, do you deduce from the fact that on the day you counted them 0.5% of the Trafalgar Square pigeons carried some form of marker rings? Were they all English birds, or did any come from Wales, Scotland, Ireland, or even further afield, say Holland, Belgium or France? Maybe you don't know, after all why should you when to you a pigeon is a pigeon is a pigeon!

As I've already said, the day I counted them there were none. Therefore based on our respective counts it is possible to say that the number of ringed racing pigeons resident in Trafalgar Square can range from between 0 up to and including a maximum of 6.



Just because you haven't personally seen it doesn't mean it's impossible for someone else to have seen 10 pigeons brought to one eyrie in one day. In this instance, the figure was quoted by Dr Andrew Dixon who has extensively studied the predation of Racing Pigeons by Peregrine Falcons, particularly in South Wales. I'm sure the ever-present 'valley boy' will have heard of him and may even know him and have helped him in his work. Therefore, the '10 per day' figure was NOT simply plucked out of the air by pigeon fanciers as you seem to imply, but rather arrived at by an acknowledged expert on Peregrine Falcons.

(Reference for any Doubting Thomas's - http://www.rpra.org/raptors.html paragraph headed 'Delaying the start of the old bird racing season.'

In future, LB, PLEASE try to do a bit of your own leg-work!

I've just read that link again and there's so much rubbish it's unbelievable. For example, I'm still not buying that peregrines can eat up to TEN P!!!!!! a day. Not unless there's some sort of peregrine sumo going on. Secondly it says that Derek Ratcliffe has said that p!!!!!! make up 80% of a peregrine diet. I've read his book and can't find any such proclamations. 40% more like. How can I begin to have respect for a report when even I (joe public with an active interest in raptors) can instantly pick out total inaccuracies?

Chris

 

[pianoman]

Thankyou, 'pianoman', that's exactly the question I'm looking for an answer to. When and if the population of feral and racing pigeons becomes exhausted, what would happen then? given that Peregrine Falcon numbers are increasing?

If, as seems to be the case in your part of the world, the Peregrine Falcons simply switched to Woodpigeons as their main prey species, how long would they last before they also became exhausted? And in turn, which other species would be subjected to, and affected by, higher predation levels?

I'm not talking about this year or next year, but 5, 10 or even 50 years from now.

Hey hold on a sec, I wasn't using this to justify any action whatsoever against peregrines. Or to suggest that feral or racing pigeons were in any danger whatsoever. Just to say that in the country as a whole, the peregrine population and the feral pigeon population are not as strongly linked as some may think.

Am I right in saying that you yourself are not advocating culling peregrines?
Or defending those who do?
If not then we can all live together in peace and harmony :hippy:

Andrew

Edit: Peregrines in my area hunt woodpigeons simply because the area is semi-rural and there are few ferals and lots of fat tasty WP.

Another Edit: And I'm referring only to the pigeon intake, not counting the other bird families that may be in their diet.

 

[colonelboris]

I'm starting to think Valley Boy is right.
This does seem to be very much a fact-hunting mission.
Makes me wonder why...

 

[Anthony Morton]

And, a little free offer on the RPRA website ...just in case anyone is in any doubt as to:
a. the warped mentality of the folks there
b. their lack of understanding of even basic ecology
c. their views towards raptors

I was beginning to think you'd gone off me, Jos, and then you provide me with this wonderful stick to beat you with. Wow! - Christmas has come early!

Many thanks indeed for publishing the sticker for all to see. Ages back in this thread - post #44 to be exact - 'dubs1967' stated that;

The threat to peregrines from pigeon fanciers is massive. A couple of years ago a certain pigeon magazine produced stickers to send off for, THESE STICKERS ENCOURAGED THE ILLEGAL KILLING OF RAPTORS.

In post #45 I challenged the author of this wholly inaccurate and utterlycomment to produce evidence to support this claim, or else apologise. Since then he has not surprisingly gone to ground on this matter. Now Jos, bless him, has published the sticker referred to, from which it is clear for all to see that no such comment has been made.

What the sticker does say, however, is that 'Hawks kill 250,000 songbirds every day'. Would you disagree with this figure, always remembering that it specifically refers to 'hawks' and makes no reference whatsoever to falcons? This well and truly puts the lie to 'dubs1967's' original comment that Peregrine Falcons, or any other falcon for that matter, are even mentioned.

As anyone who has studied basic raptor predation will know, the figure of 250,000 (a quarter of a million) songbirds killed per day is the total number attributable to Sparrowhawks alone.(Reference Ian Newton's book 'The Sparrowhawk' and extrapolated from the figures given in the 'Feeding Habits' paragraph. (How am I doing this time, AR?)

So then, Jos, how can you possibly state at a) above that the sticker shows the 'warped mentality of the folks there' (presumably you mean at the RPRA) when it clearly does no such thing? How can you possible even suggest at b) that the use of the peer-reviewed figure that 250,000 songbirds which are being killed every day by Sparrowhawks shows a lack of understanding of basic ecology? And finally, how can you further claim at c) that this in any way, shape, or form indicates the RPRA's overall view of raptors?

In fact, isn't this all assumption on your part?

 

[London Birder]

I wouldn't worry Andrew, I doubt anyone on this thread thought you were trying to justify anything negative toward raptors for a micro-second ... some will just jump on the comments they consider the most expedient to their own outlook and try twist things that way ... you're right, both PF's and raptor enthusiasts/birders could live alongside each other quite harmoniously if it wasn't for elements within the former seeking the destruction of individual birds on the basis that it disrupts their hobby ... sad, misinformed and worrying, and for what!

 

[Andrew Rowlands]

Alright then, to put an end to this nit-picking, would you (and presumably several others) be happier if instead of writing in general terms I amended the statement you seem to be having so much trouble with to read:-

"... but I flatly refuse to accept that they are single-handedly responsible for the death of every raptor, or the failure of their nest IN THE SOUTH WALES VALLEYS."

Just remember that you have forced me to be that specific, rather than allowing the matter to be discussed in more general terms without pointing a finger at any one group or individual.

The area you are referring to is much smaller than the "South Wales Valleys".

Try, "the area of the South Wales Valleys covered by valley boys observations". This is a much smaller area, consisting of (if I remember it correctly) 15 potential or historic sites where this year 5 pairs attempted to breed, with only one pair raising young.

Now that we are being area specific, how many references would you like? As for the casual observer, this could be anyone from around the world visiting this forum - including pigeon fanciers of course. It could also be Mrs Morton who occasionally has a browse here but certainly does not have any strongly held beliefs about any species of bird.

Naturally you are entitled to your opinion regarding my comments, just as I am mine. If you don't like what I'm saying, then why not exercise your right to press the 'ignore' button. What I write is MY opinion on matters. If I quote from another source I try to give references.

I would like all references, of course, as would the casual observer if they have any chance of making an informed decision. As to Mrs Morton (if indeed, such a person exists), I suspect that her 'beliefs' may alter depending on whether Mr Morton was within earshot at the time.

I'm more likely to hit the delete button than the ignore button when it comes to some of your posts, Anthony. I don't think it would be in the best interests of the forum if moderators were to use the ignore facility at a Members behest, indeed, it would be frowned upon, I'm sure.

Before you do, however, South Wales has (had?) one of, if not the, highest population densities of Peregrine Falcons in the UK, so what makes you think that something (anything) which affects that population at the localised level could not eventually affect them on a national basis? Better still, can you guarantee that it won't?

Has (had?) it?

Are you referring to the decline in lofts or the increase in human persecution?

Please, be specific and accurate, quoting any references.

Guarantee? Haven't you been reading the replies again?

 

[London Birder]

According to Dr. Dixon ...

'a typical territorial pair of Peregrines rearing two chicks would kill an estimated 355 (domesticated) pigeons per year'

wouldn't 10 a day = 3,650 or is my maths shot to bits?

 

[CBB]

What the sticker does say, however, is that 'Hawks kill 250,000 songbirds every day'. Would you disagree with this figure, always remembering that it specifically refers to 'hawks' and makes no reference whatsoever to falcons? This well and truly puts the lie to 'dubs1967's' original comment that Peregrine Falcons, or any other falcon for that matter, are even mentioned.

As anyone who has studied basic raptor predation will know, the figure of 250,000 (a quarter of a million) songbirds killed per day is the total number attributable to Sparrowhawks alone.(Reference Ian Newton's book 'The Sparrowhawk' and extrapolated from the figures given in the 'Feeding Habits' paragraph. (How am I doing this time, AR?)

So then, Jos, how can you possibly state at a) above that the sticker shows the 'warped mentality of the folks there' (presumably you mean at the RPRA) when it clearly does no such thing? How can you possible even suggest at b) that the use of the peer-reviewed figure that 250,000 songbirds which are being killed every day by Sparrowhawks shows a lack of understanding of basic ecology? And finally, how can you further claim at c) that this in any way, shape, or form indicates the RPRA's overall view of raptors?

In fact, isn't this all assumption on your part?[/QUOTE]



Is this figure world wide?

 

[Andrew Rowlands]

(Reference Ian Newton's book 'The Sparrowhawk' and extrapolated from the figures given in the 'Feeding Habits' paragraph. (How am I doing this time, AR?)

It shows that you can do it, well done :clap: :clap: :clap:

Next time you don't however, (and on subsequent occasions) I may just take it upon myself to delete the whole Post until you remember how to do it. You want to be taken seriously or not?

Would you mind awfully if you went back through the thread and answered the questions you'd chosen to ignore (seems to me that you'd triggered most of them ... )?

 

[Richard D]

...
a) above that the sticker shows the 'warped mentality of the folks there' (presumably you mean at the RPRA) when it clearly does no such thing? How can you possible even suggest at b) that the use of the peer-reviewed figure that 250,000 songbirds which are being killed every day by Sparrowhawks shows a lack of understanding of basic ecology? And finally, how can you further claim at c) that this in any way, shape, or form indicates the RPRA's overall view of raptors?

Anthony -

a) You are surely not suggesting that the use of the figure 250,000 Killed, combined with the slogan Save Our Songbirds is merely a factual statement devoid of any intent?

b) The use of the phrase Save Our Songbirds linked with the the fact that 250,000 songbirds are killed by hawks is clearly either a lack of understanding of basic ecology or equally worrying a deliberate attempt to mislead. Predation by native predators has in pretty much every serious study been shown to have no effect on breeding populations. i.e. There is no relationship between the amount of songbirds hawks eat and the survival of songbirds. Linking the two ideas is either deliberately misleading or merely showing ignorance beyond the norm.

c) The RPRA clearly states it wants the right to control raptors in other sources (e.g. their web site).

Richard

 

[colonelboris]

'Hawks eat over 250,000 songbirds daily'

That works out at 3.1 songbirds per hawk per day (40,100 sparrowhawk pairs, 300 goshawk pairs). According to the Hawk Conservancy, songbirds make up 90-98 % of sparrowhawk prey, so you can add roughly half a vole to that number.
Blue tits, 7 million birds, av winter population, double their numbers when the nestlings fledge to 14 million and are back to 7 million by the winter. So on blue tits alone, most the sparrowhawk population can survive without making a difference to the population of blue tits.
Of course, when you factor in chaffinches, greenfinches, great tits, house sparrows, etc, it's not that a big a deal.
Plus the sparrowhawks round here make a good meal out of wood pigeons (7.3 million birds, four young per year), which something needs to in order to keep the population stable.
There's also a nice article here on why sparrowhawks don't appear to affect bird numbers.

If all the sparrowhawks and goshawks suddenly disappeared, then the 9.2 million birds a year they eat (from the 250,000 daily figure) would starve to death, which is a much more drawn out process than being snacked on.

That's if sparrow- and goshawks do eat 3.1 birds a day.

 

[mothman]

Anthony -

a) You are surely not suggesting that the use of the figure 250,000 Killed, combined with the slogan Save Our Songbirds is merely a factual statement devoid of any intent?

b) The use of the phrase Save Our Songbirds linked with the the fact that 250,000 songbirds are killed by hawks is clearly either a lack of understanding of basic ecology or equally worrying a deliberate attempt to mislead. Predation by native predators has in pretty much every serious study been shown to have no effect on breeding populations. i.e. There is no relationship between the amount of songbirds hawks eat and the survival of songbirds. Linking the two ideas is either deliberately misleading or merely showing ignorance beyond the norm.

c) The RPRA clearly states it wants the right to control raptors in other sources (e.g. their web site).

Richard

In fact I want a cull of songbirds because they feed on endangered moths and their larvae!! (Before you castigate me ,I'm not serious, but just illustrating how ridiculous the RPRA look)

 

[London Birder]

but hey, we all know what this is REALLY all about don't we ...

why no campaign to 'Save Our Slum Doves'?

 

[edenwatcher]

but hey, we all know what this is REALLY all about don't we ...

why no campaign to 'Save Our Slum Doves' ?

Save Our Doves? SOD has a much better ring to it.

Rob

 

[CBB]

'Hawks eat over 250,000 songbirds daily'

That works out at 3.1 songbirds per hawk per day (40,100 sparrowhawk pairs, 300 goshawk pairs). According to the Hawk Conservancy, songbirds make up 90-98 % of sparrowhawk prey, so you can add roughly half a vole to that number.




Thanks CB. When explained properly, it makes perfect sense. I think even AM would agree that the sticker in question is inflammatory.

 

[lockbreeze926]

the 9.2 million birds a year they eat (from the 250,000 daily figure)

I am certain that the figures quoted are a pile of pish, and the methodology used to extrapolate is clearly nonsense, but in the interests of accuracy, we need to acknowledge that 250k a day is actually 92 million a year, not 9.2 (which, actually, is one of the things that discredits the "case").

 

[James Lowther]

... dredged up from the bottomless well of bullshit ...

that's the thing that always amazes me about Anthony,
that well really IS bottomless

you can out-argue, out-think, out-manoeuvre him

but you cannot out-last him

He can't be bargained with, can't be reasoned with! He doesn't feel pity or remorse or fear, and he absolutely will not stop. EVER! Until you are dead!
!!!

(or maybe just until everyone else has given up)

p.s. thanks to Tim, for putting meat on the bones of the basic ecology...

 

[colonelboris]

Actually, I've missed another zero, so you can scrub the bit about blue tits alone feeding them. It's 91.3 million birds they eat a year, but even so, it keeps the numbers stable of the more common birds...

edit: Sorry lockbreeze, just seen your post, and you're quite right.