Shooting and conservation

[earthdragon64]

Originally Posted by wolfer

There's no need to attempt to keep alive the idea that Crows and Squirrels eat eggs and chicks/fledgelings of many species, as anyone who has any idea knows that it's a fact.

In the real world however, when predators such as Crows and Squirrels are finding many other food sources, especially in urban areas where they get well fed, and in some cases are actually protected, rather than suffer a decline, they are increasing.

Whilst I wouldn't deny that some Crows and some Squirrels probably eat some eggs and chicks, it isn't something I've witnessed, although I have witnessed Jackdaws catching and eating Siskins, fairly well grown ones at that. As I still get over 20 Siskins daily in my garden at certain times of year, I can't see that this predation has had an adverse impact.

Also if Crows and Squirrels are finding many other food sources, this surely reduces the pressure on eggs and chicks? I'm not quite following the logic that if a predatory species is finding more food sources in a wider area, that will increase pressure on one particular type of food source.

Originally Posted by wolfer

Not even you rkb could argue that we've seen an absolute explosion in Crow and Magpie numbers over the last 30-40 years.

I don't know if RKB will argue with this rather sweeping generalisation, but I will. In my part of the UK at least, I see more Osprey in a year than I do Magpies, for example in 2010 I saw 17 Osprey at 9 locations, but only 3 Magpies at 2 locations. I've lived here for 18 years and haven't witnessed any increase in Carrion or Hooded Crows either.

My main concern locally is that our iconic birds of prey are still sadly falling prey to the belief by some "Sporting" estates that they are above the law and can do what they like to protect their interests.

Regards, Audrey.

[pressld2]

Originally Posted by earthdragon64

Also if Crows and Squirrels are finding many other food sources, this surely reduces the pressure on eggs and chicks? I'm not quite following the logic that if a predatory species is finding more food sources in a wider area, that will increase pressure on one particular type of food source.

Hi Audrey,

I think the idea is that if there is more of the other food sources available, usually human provided either in the form of refuse or deliberate feeding, then more of the crows and squirrels will survive the winter, meaning there will be more of them around in the spring to predate eggs and chicks. There may well be some truth in this but it still doesn't alter the fact that crows and squirrels, while certainly taking some eggs and chicks of some species, are not a significant factor in the decline of songbirds. And definitely not of nuthatches, treecreepers and GSWs.

All the studies point to habitat loss as the most significant factor in songbird decline, with predation, by anything, only being of concern with endangered species on a very localised basis.

I'm rather fond of corvids but I'll happily swap you some of my magpies and crows for a few of your ospreys! I'll bring 'em with me in August...

Dave P.

[RKB]

Population trend of magpie: BTO - Breeding Birds of the Wider Countryside: Magpie

Carrion Crow: BTO - Breeding Birds of the Wider Countryside: Carrion Crow

Nuthatch: BTO - Breeding Birds of the Wider Countryside: Nuthatch

Great Spotted Woodpecker: BTO - Breeding Birds of the Wider Countryside: Great Spotted Woodpecker

Treecreeper: BTO - Breeding Birds of the Wider Countryside: Treecreeper

All of them increasing, as are squirrels, except Treecreeper (fairly flat 1967-2004). So it's hard to imagine how such an explosion of 'predators' could have occurred at the same time as their 'prey' if they are supposed to be having an impact on them.

The mark of a professional ecologist, or anyone of a scientific/logical mind, is to be willing to revise their opinion based on new/stronger evidence presented to them. Those who hold opinions based on doctrine rather than evidence are not scientists (be it ecologist or any other type of -ology), as they are not using the 'scientific method' which is the cornerstone of all scientific thinking. Review in the light of evidence is what science is, and therefore it's what ecology is too.

[RoyW]

Originally Posted by wolfer

I've repeated myself far more than I would normally be prepared to

Without meaning any disrespect Wolfer, I would say that this pretty much sums up why many people won't accept your 'argument' - you have been repeating yourself without actually answering the questions raised or providing any evidence to support your viewpoint.
Many of the "simple facts" that you wish people to accept are not backed up by evidence.

Originally Posted by RKB

No, they are told it is a fact by people like yourself, who haven't done any research themselves, don't seem to know the other dozens of studies out there, and haven't read the book written by a Professor in the subject. That's not the same thing as a fact. That's just accepting what you're told without making a reasoned decision on the basis of the evidence available.

I would actually have to agree with this statement from Wolfer - I think that it is a fact that crows and squirrels eat the eggs and young of many species. I consider this to be well documented - but it does not mean that they take the eggs and young of all species, nor does it mean that the number of nests/young taken will be significant enough to cause any problems with the population of the prey species (which is what the implication seems to be).
What is in dispute is the suggestion that control of corvid numbers is a useful measure to aid the biodiversity of other species (including the suggestion that crows have any effect on woodpeckers etc), except in specific circumstances (eg. control in a limited area to benefit the conservation of specific scarce species).

Wolfer:
I'm not quite sure what it is that is "right in front" that myself and others "refuse to see" - perhaps if you can see fit to post again, but with the addition of new information to back up your opinions, I might understand.

[earthdragon64]

Originally Posted by pressld2

Hi Audrey,

I think the idea is that if there is more of the other food sources available, usually human provided either in the form of refuse or deliberate feeding, then more of the crows and squirrels will survive the winter, meaning there will be more of them around in the spring to predate eggs and chicks. There may well be some truth in this but it still doesn't alter the fact that crows and squirrels, while certainly taking some eggs and chicks of some species, are not a significant factor in the decline of songbirds. And definitely not of nuthatches, treecreepers and GSWs.

I fully understand what you're saying, but that wasn't quite how wolfer explained things. Also, if the extra, new food sources are available all year round, including during breeding season, then it should all balance out.

Originally Posted by pressld2

All the studies point to habitat loss as the most significant factor in songbird decline, with predation, by anything, only being of concern with endangered species on a very localised basis.

Changing farming practices can also be a concern, but some can be turned around. I was on Benbecula last week and was at the Balranald RSPB reserve on North Uist, there was an info board detailing successes with changing crofters practices to benefit Corncrakes and Corn Buntings.

Originally Posted by pressld2

I'm rather fond of corvids but I'll happily swap you some of my magpies and crows for a few of your ospreys! I'll bring 'em with me in August...

Dave P.

We're keeping the Ospreys, you can't have them! Spare Magpies would be welcome, and Nuthatches, I've never actually seen a Nuthatch.

Regards, Audrey.

[pressld2]

Originally Posted by earthdragon64

Also, if the extra, new food sources are available all year round, including during breeding season, then it should all balance out.

Could well do. I don't know if there have been any proper studies into this yet.

Originally Posted by earthdragon64

We're keeping the Ospreys, you can't have them!

I don't blame you!

Originally Posted by earthdragon64

Spare Magpies would be welcome, and Nuthatches, I've never actually seen a Nuthatch.

Maybe in a few years. According to the BTO page that RKB linked to, they've been spreading north and are now into southern Scotland. Coming soon, to a forest near you...

Dave P.

[RKB]

Originally Posted by RoyW

I would actually have to agree with this statement from Wolfer - I think that it is a fact that crows and squirrels eat the eggs and young of many species. I consider this to be well documented

Very much agree for corvids - I mentioned waders earlier. But the evidence for squirrels is actually very poor. The BTO have looked for relationships and found little or no effect: BBC - Earth News - Grey squirrels 'do not harm woodland birds in England'

Originally Posted by RoyW

but it does not mean that they take the eggs and young of all species,

That's the nub of the thread. Are crows and squirrels likely to be responsible for the pattern observed by the OP in the two woods for the hole-nesting species. It's one thing to agree that crows take lapwing eggs, but quite another to suppose they're doing the same thoing to Nuthatches, or that squirrels are doing it to anything, and then decide that we need shoot crows and squirrels to help nuthatches et al.

Originally Posted by RoyW

nor does it mean that the number of nests/young taken will be significant enough to cause any problems with the population of the prey species (which is what the implication seems to be).

Ummm, that contradicts the above, a little. It's well documented that e.g. crows can suppress populations of waders and gamebirds.

[RKB]

Originally Posted by pressld2

Maybe in a few years. According to the BTO page that RKB linked to, they've been spreading north and are now into southern Scotland. Coming soon, to a forest near you...

Dave P.

Quite a few in the central belt now, I think. There's a large expanse of thinly-wooded hills in northern England/souther Scotland that short-dispersal species like Nuthatch have found hard to cross in sufficient numbers to colonise. But afforestation and population pressure in the south now seems to have provided enough recruits/corridors to make the leap. Scotland has plenty of habitat for Nuthatches and e.g. Marsh Tits, so the reason they weren't there seemed to be habitat gaps.

[RoyW]

Originally Posted by RKB

Very much agree for corvids - I mentioned waders earlier. But the evidence for squirrels is actually very poor. The BTO have looked for relationships and found little or no effect:

The "fact" given by Wolfer was simply "There's no need to attempt to keep alive the idea that Crows and Squirrels eat eggs and chicks/fledgelings of many species, as anyone who has any idea knows that it's a fact."
Squirrels may only take very insignificant numbers of eggs and chicks, but they are known to take them - and they aren't at all fussy about the species. Crows also take eggs and chicks/fledglings of many different species (with evidence that they can have a negative effect on a few of these).
The evidence for negative effects may be poor, or completely lacking, but the "fact" given is not - if the statement had been "There's no need to attempt to keep alive the idea that Crows and Squirrels eat eggs and chicks/fledgelings of many species, and by doing so negatively affect their populations, as anyone who has any idea knows that it's a fact." then it could be argued that there would be insufficient evidence to treat it as a fact.

Originally Posted by RKB

Ummm, that contradicts the above, a little. It's well documented that e.g. crows can suppress populations of waders and gamebirds.

No, no contradiction. Predation by crows has been shown to affect the populations in some cases, but it does not necessarily follow that predation of the eggs and/or young of a species will have an effect.
There is evidence that crows can suppress populations of waders and gamebirds, but it is also well known that they will take eggs and fledgling of other species without having any effect (eg. I have witnessed attacks on Blackbird and Blue Tit fledglings, and seen a crow with what looked like a pigeons egg - examples of predation in all three cases which are unlikely to have resulted in any problems with the respective populations).



I agree with pretty much everything that you have said RKB, but I don't see that you can successfully argue against the "fact" given - the implication that the taking of a small number of eggs/young will affect populations is another matter!

[wolfer]

Originally Posted by RoyW

Without meaning any disrespect Wolfer, I would say that this pretty much sums up why many people won't accept your 'argument' - you have been repeating yourself without actually answering the questions raised or providing any evidence to support your viewpoint.
Many of the "simple facts" that you wish people to accept are not backed up by evidence.



I would actually have to agree with this statement from Wolfer - I think that it is a fact that crows and squirrels eat the eggs and young of many species. I consider this to be well documented - but it does not mean that they take the eggs and young of all species, nor does it mean that the number of nests/young taken will be significant enough to cause any problems with the population of the prey species (which is what the implication seems to be).
What is in dispute is the suggestion that control of corvid numbers is a useful measure to aid the biodiversity of other species (including the suggestion that crows have any effect on woodpeckers etc), except in specific circumstances (eg. control in a limited area to benefit the conservation of specific scarce species).

Wolfer:
I'm not quite sure what it is that is "right in front" that myself and others "refuse to see" - perhaps if you can see fit to post again, but with the addition of information to back up your opinions, I might understand.

new

I wasn't intending to post on this thread anymore, but I feel that I should attempt to clarify my point a little.
The only thing I've said and repeated is that Crows and Squirrels do eat many species of Birds, and their eggs and chicks. As correctly stated by Roy, it's well documented, but I don't go simply on what others state, my reasons for stating such is that I've witnessed it far too many times to pass off as being rare.
I did say that I'd not actually personally seen Crows in the process of destroying Nuthatch nests, although on several occasions the evidence that a nest has been destroyed by a Crow has been very strong.
I can't recall saying that either Crows or Squirrels were the main factor in any species decline, as that isn't my view.
I also stated repeatedly that I believe pest control has a positive effect on biodiversity. I base this on my own and the work of many others, there tends to be a greater range of biodiversity in areas where effective and responsible pest control is carried out. I don't feel that this is just coincidence.

RKB does seem hell bent on arguing and nit picking, which is his right, and I've no complaint with that.
So to end on a lighter note, right throughout his posts a bigger mental picture of him has has been building - picture Nevillie Chamberlain on his return from Berlin - RKB waving his piece of paper in front of masses of songbirds, while proclaiming 'you've nothing to worry about, it says here that Crows won't eat you'.
No offence meant RKB, I just hope you've a sense of humour to go with your ego.