Corvid control (1 Viewer)

ChrisKten · Aug 10, 2012

Ignoring the fact that I can find little evidence that Corvids have a significant (causes a decline) effect on other species (Yes they kill young and take eggs, but they was doing it long before Humans arrived. Other species have evolved to compensate for predation: number of broods - clutch size - selection of nesting site, etc.), I've a few questions about controlling Corvids.

It seems to be widely accepted that control of Corvids (Magpies being the ones most often affected) is necessary in some (many/all?) places, but why is it accepted? Why is it necessary to control a Native species?

I'd guess that a few sensitive sites/species might need a bit of extra protection, but for how long? Won't the protected birds behave differently? When they disperse, won't they be liable to nest in places where they'd be vulnerable to Corvids (too low - too exposed etc)? Places that they wouldn't have selected naturally, had we not fooled them into feeling safe in areas where Corvids were absent (are they absent, or just reduced in number?). Or will the birds stay where they are? Safe for ever in protected areas? A bit like a Zoo I guess|=)|

I'm not sure how this all works; will these protected areas always be devoid of Corvids? Will the areas be extended when the vulnerable species increase in numbers?

I've typed this as I was thinking, rather than thought about what to type, so there might be the odd silly question in there somewhere|=)|

George London · Aug 10, 2012

Perhaps its a question of diversity?

Long before humans every bird species had endless/sufficient/adequate areas of habitat. Corvid populations had endless/sufficient/adequate supplies of eggs etc.
Humans destroy habitats, some/many birds are affected negatively. Particularly 'specialists' like bitterns, bearded tits, skylarks etc etc.
I haven't looked for reports/surveys so I am entering unknown waters now, but would suggest intuitively that corvids have not been impacted in the way many other species have been.
This leaves a situation where the same number of corvids are predating a much smaller 'pool' of eggs etc generally. When that crow takes a single willow tit egg it has a disproportionate affect on the willow tit population.

Thus in this instance control of a widespread 'common' species is necessary to ensure as much indigenous diversity as possible remains in the scarred lands we humans have created.

My view is that the greater of two evils is to stand by and allow vulnerable species to be 'disproportionately' affected, rather than the lesser (IMHO) which is controlling the situation WE created by managing corvid populations. Yes, its playing God, but we already did that by destroying the habitats and we have an obligaion to 'play God' in salvaging what we have left.

The sight of a Hawfinch nest last year being predated by a jackdaw was 'life' but seemed pretty silly and unnecessary to me. This year it managed to nest again... guess what happened?

Finally I don't think any gamekeeper has ever totally eradicated corvids from any area in the UK and as such i can't see a situation where a native species population 'evolves' to not be wary of corvids.

Now off to put some chainmail on and wait for the statisticians to tear me to piecesB

Nightranger · Aug 10, 2012

ChrisKten said:
Ignoring the fact that I can find little evidence that Corvids have a significant (causes a decline) effect on other species (Yes they kill young and take eggs, but they was doing it long before Humans arrived. Other species have evolved to compensate for predation: number of broods - clutch size - selection of nesting site, etc.), I've a few questions about controlling Corvids.

It seems to be widely accepted that control of Corvids (Magpies being the ones most often affected) is necessary in some (many/all?) places, but why is it accepted? Why is it necessary to control a Native species?

I'd guess that a few sensitive sites/species might need a bit of extra protection, but for how long? Won't the protected birds behave differently? When they disperse, won't they be liable to nest in places where they'd be vulnerable to Corvids (too low - too exposed etc)? Places that they wouldn't have selected naturally, had we not fooled them into feeling safe in areas where Corvids were absent (are they absent, or just reduced in number?). Or will the birds stay where they are? Safe for ever in protected areas? A bit like a Zoo I guess|=)|

I'm not sure how this all works; will these protected areas always be devoid of Corvids? Will the areas be extended when the vulnerable species increase in numbers?

I've typed this as I was thinking, rather than thought about what to type, so there might be the odd silly question in there somewhere|=)|

Hi Chris,

It is quite a complex issue and if anyone reads this who opposes all killing then I apologise in advance. Gamekeepers and farmers can control Corvids to protect stock and effectively, this has not be challenged for a long time. Whether indiscriminate control has a real effect is debatable but Corvids have not suffered in terms of numbers so it is difficult to form a clear opposition except on animal welfare grounds (that is outside the scope of your questions here so I will leave it to another thread).

In terms of conservation, it is about thinking of the straw that broke the camel's back. Species decline is far more complicated than it is ever portrayed by the RSPB et al and I find it frustrating to read another press release about say 'the effects of intensive farming'. The reality is that there are most often a lot of factors involved in species declines and the key is that removing one of those factors can help. It is doubtful whether Corvids actually cause species declines but they can be critical (as can potentially, any predator) when populations are low in reducing breeding success - actually this is more true of single-brooded birds than it is of multi-brooded species that produce some broods when Corvids are less likely to be foraging for nests. This means that local control (which is aimed at reducing the density of Corvids, not total elimination) can be useful in giving a target species a leg-up for a few seasons.

Robin Edwards · Aug 10, 2012

I think George has summed things well. In a world undamaged by man, species would sort themselves out but in our real world, pragmatic conservationists will want to apply controls to prevent complete loss of fragmanted and scarce species. Stone Curlew might be an example where localised, humane, licenced control of gulls, corvids, fox & stoat, prevents total loss and some degree of recovery. Each of these predator species could have artificially high populations due to other affects man has had over many years - mass release of gamebirds might be an example.

There is of course the view that man's behaviour and evolutionary path to self-destruction is natural and species loss equally so.

Others will view that any control that involves killing one species to protect another is unacceptable.

My view is that many species can be saved for future generations through education and removal of medieval mindset with some species control as a last resort. There are good examples where species have recovered with man's help and without loss of other species along the way, similarly there are examples where ignorance and greed prevail and conservation is failing.

Whilst I wouldn't make a good gamekeeper, I accept that some local controls are necessary if we want to maintain species diversity.

On the subject of Corvids - I think Rook get a really bad deal and just because their black and crow-like, gamekeepers prefer to treat them the same as crows.

And then there's species/corvid control in the name of sport that to me will always be abhorrant and medieval.

ChrisKten · Aug 10, 2012

Thanks for some interesting (to me) replies.

I'd say that I'm against killing (controlling/culling/...) generally, and it's not something that I'd be happy doing myself, but I'm aware that others have found it necessary (after considering alternatives?) to kill one species to protect another.

It seems to be about the numbers; which makes me wonder what would happen if one scarce/threatened species threatened another scarce/threatened species?

To me, Corvids are a special case, as they're very intelligent. For some reason it makes me feel a bit uncomfortable knowing that another "intelligent" species is being killed; then again, we kill each other|=)|

Nightranger · Aug 10, 2012

ChrisKten said:
I'd say that I'm against killing (controlling/culling/...) generally, and it's not something that I'd be happy doing myself, but I'm aware that others have found it necessary (after considering alternatives?) to kill one species to protect another.

I would have been right beside you a few years ago but I suppose I have become a little more realistic as time has gone on. It is not that I agree with some of the reasons for control or that I am happy that it has to take place. I even agree with Robin in that I would also make a poor gamekeeper so I am glad I don't have to do the killing. As George says, as a species, we have changed the world around us and that means we have to accept responsibility for trying to stop things running out of control. There is an argument that some (not all, Robin is right about rooks getting a bad deal) Corvids particularly benefit from human activities so the ultimate question is whether their numbers are out of balance. I am not totally convinced by this idea but whilst there is no evidence that any species of Corvid is suffering as a result of controls, I do not see a stromng conservation case against control.

Nightranger · Aug 10, 2012

ChrisKten said:
It seems to be about the numbers; which makes me wonder what would happen if one scarce/threatened species threatened another scarce/threatened species?

It is a good question Chris and even though it is hypothetical and probably represents an impossible scenario it is worth theorising on. I think the simple answer is that there could be no justification for controlling any species that was already threatened/scarce, irrespective of what it was doing to survive. Assuming that both species were native to the country in question and there was no other conservation issue that muddied the waters, it would have to be a leave well alone although I assume some programme of captive breeding would have to be put in place for both species as an alternative strategy.

AlfArbuthnot · Aug 10, 2012

Nightranger said:
In terms of conservation, it is about thinking of the straw that broke the camel's back. Species decline is far more complicated than it is ever portrayed by the RSPB et al and I find it frustrating to read another press release about say 'the effects of intensive farming'. The reality is that there are most often a lot of factors involved in species declines and the key is that removing one of those factors can help. It is doubtful whether Corvids actually cause species declines but they can be critical (as can potentially, any predator) when populations are low in reducing breeding success - actually this is more true of single-brooded birds than it is of multi-brooded species that produce some broods when Corvids are less likely to be foraging for nests. This means that local control (which is aimed at reducing the density of Corvids, not total elimination) can be useful in giving a target species a leg-up for a few seasons.

Do you extend that logic to raptors, and think that they should be controlled for a few seasons to give other species a leg up where there is a high predation risk? I am thinking here of common and widespread species that are not of conservation concern, such as Sparrowhawk.

Sparrowhawks are a major predator of Grey Partridges, especially where partridges are already under pressure and especially of pre-breeding adults. http://www.gwct.org.uk/research__surveys/species_research/birds/grey_partridge_bap_species/223.asp

Is it right/wrong that Carrion Crows can be killed to prevent them predating Grey Partridge eggs, but Sparrowhawks cannot be killed to prevent them killing the birds that would lay those eggs?

fugl · Aug 10, 2012

ChrisKten said:
For some reason it makes me feel a bit uncomfortable knowing that another "intelligent" species is being killed; then again, we kill each other|=)|

And you're comfortable with that?

AlfArbuthnot · Aug 10, 2012

Robin Edwards said:
On the subject of Corvids - I think Rook get a really bad deal and just because their black and crow-like, gamekeepers prefer to treat them the same as crows.

I would say that it is the Crows getting the bad deal, at least in the agricultural lowlands. There is absolutely no reason at all to cull Carrion Crows or Magpies on any commercial shoots except upland Grouse moors. Virtually all of the many millions of Pheasants and Red-legged Partridges that are shot as game are bought in as chicks and reared on. Almost none come from eggs laid in the wild, and it is only wild eggs that are vulnerable to crows or magpies. Therefore, virtually no Pheasant or Red-legged Partridge game is at risk from crows, yet they are still trapped and shot as pests.

On the other hand, Rooks are an agricultural pest that do damage crops, so there is a case for controlling them on your farm if it your crops they are damaging. http://www.jstor.org/discover/10.2307/2401752?uid=3738032&uid=2&uid=4&sid=21101139875827

I cannot see any case for controlling Crows or Magpies on such farms or shooting estates.

AlfArbuthnot · Aug 10, 2012

fugl said:
And you're comfortable with that?

It rather depends on the reason. If it were enemy troops in 1944 then many people would be very comfortable indeed, and would see no reasonable alternative, because it was done in the defence of something that they valued more greatly than the life the enemy who may be trying to kill them also. By the same token, people claim to kill crows in the defence of something that they value more greatly than the life of the crow.

fugl · Aug 10, 2012

Another wrinkle is when predators--usually corvids or birds of prey--are killed for no good reason at all. Try to tell a Nevada hunter that ravens aren't a significant threat to Sage Grouse (currently a species of conservation concern in the state), for example, citing all the science you want, & see where that gets you. Dto for mountain lions & mule deer (the latter currently common as mud as always). The fact is that simple people like simple "solutions" & nothing's simpler (& more fun!) than blazing away at varmints through the side-window of a pickup truck.

fugl · Aug 11, 2012

AlfArbuthnot said:
It rather depends on the reason. If it were enemy troops in 1944 then many people would be very comfortable indeed, and would see no reasonable alternative, because it was done in the defence of something that they valued more greatly than the life the enemy who may be trying to kill them also. By the same token, people claim to kill crows in the defence of something that they value more greatly than the life of the crow.

You've taken my light-hearted remark rather more seriously than it deserves, I think.

[And for the record, I yield to no man in my distaste for Nazi soldiery].

AlfArbuthnot · Aug 11, 2012

fugl said:
You've taken my light-hearted remark rather more seriously than it deserves, I think.

Not really, although it was an opportunity to highlight that, no matter much we think we have lines in the sand and absolute limits whrn it comes to 'right and wrong', everything is relative and flexible.

fugl said:
[And for the record, I yield to no man in my distaste for Nazi soldiery].

But that's because you are not a Nazi. If you were, and many millions of people were fully signed up to the ethos, and if you were a young female Berliner in the summer of '45, then you'd probably see things quite differently. In the same way, a gamekeeper or a trigger-happy redneck will have different personal priorities than a fully signed-up member of the RSPB or Audobon. Who is 'right' depends on which group you belong. Just as it does for Nazis and Allies. After all, who was worse, Hitler or Stalin? Belsen or Nagasaki?

fugl · Aug 11, 2012

AlfArbuthnot said:
Not really, although it was an opportunity to highlight that, no matter much we think we have lines in the sand and absolute limits whrn it comes to 'right and wrong', everything is relative and flexible.

But that's because you are not a Nazi. If you were, and many millions of people were fully signed up to the ethos, and if you were a young female Berliner in the summer of '45, then you'd probably see things quite differently. In the same way, a gamekeeper or a trigger-happy redneck will have different personal priorities than a fully signed-up member of the RSPB or Audobon. Who is 'right' depends on which group you belong. Just as it does for Nazis and Allies. After all, who was worse, Hitler or Stalin? Belsen or Nagasaki?

My God, it seems I've got a tiger by the tail. You don't let up, do you?
And if I were "young female Berliner" (in full Nazi regalia maybe)? Wow, I'm starting to get seriously hot!

On a non-sarcastic note, do you really want to continue this? My guess is that we probably don't differ all that much on the big philosophical stuff.

Nightranger · Aug 11, 2012

AlfArbuthnot said:
It rather depends on the reason. If it were enemy troops in 1944 then many people would be very comfortable indeed, and would see no reasonable alternative, because it was done in the defence of something that they valued more greatly than the life the enemy who may be trying to kill them also. By the same token, people claim to kill crows in the defence of something that they value more greatly than the life of the crow.

Black card situation, Alf (watch Red Dwarf). It is inappropriate to use this kind of comparison in conservation as I am sure you know.

Nightranger · Aug 11, 2012

AlfArbuthnot said:
Do you extend that logic to raptors, and think that they should be controlled for a few seasons to give other species a leg up where there is a high predation risk? I am thinking here of common and widespread species that are not of conservation concern, such as Sparrowhawk.

Sparrowhawks are a major predator of Grey Partridges, especially where partridges are already under pressure and especially of pre-breeding adults. http://www.gwct.org.uk/research__surveys/species_research/birds/grey_partridge_bap_species/223.asp

Is it right/wrong that Carrion Crows can be killed to prevent them predating Grey Partridge eggs, but Sparrowhawks cannot be killed to prevent them killing the birds that would lay those eggs?

'Is this the five minute argument or the full half hour?'

Come on Alf, you are bored and looking for a bit of controversy. Personally, I like a good debate too but this thread was started with good intentions and to scatter-gun the debate in different directions is getting perilously close to Trollery. :C

Note on edit: Alf, you are quoting the GWCT here so it is time for you to call your position and tell us all why the sparrowhawk has such a bad rep' in your eyes. I cannot see why the sparrowhawk is a major predator on grey partridges when most people see them taking pigeons (or doves).

Irish Kite · Aug 11, 2012

These Islands appear to a have a far densier population of Corvids compared to many places on the near continent. I put this down to lack of Corvid predators - notably Goshawks,Eagle Owls etc.

Robin Edwards · Aug 11, 2012

Irish Kite said:
These Islands appear to a have a far densier population of Corvids compared to many places on the near continent. I put this down to lack of Corvid predators - notably Goshawks,Eagle Owls etc.

You may well be right although I found from a recent visit to the Hortobagy NP in Hungary that Hooded Crow is controlled to protect ground nesting birds and yet there are plenty of raptors to be found.

In the northen Zemplen hills Eagle Owl and Goshawk are common-place as are the Wood Pigeons and Hoodies.

Here in the UK I think that corvid populations do well because the land is generally one big bird table with farming intensity providing both seed and ground inveterbrates. I'm not sure if a few Goshawk or Eagle Owl would make much difference to their populations though?

AlfArbuthnot · Aug 11, 2012

fugl said:
My God, it seems I've got a tiger by the tail. You don't let up, do you?
And if I were "young female Berliner" (in full Nazi regalia maybe)? Wow, I'm starting to get seriously hot!

On a non-sarcastic note, do you really want to continue this? My guess is that we probably don't differ all that much on the big philosophical stuff.

I was simply making the point that a lot of statements are made on special-interest forums such as this that are taken as a given (i.e. 'it is wrong to kill'), without acknowledgement that the opposing group have a completely different viewpoint that they feel comfortable with. We probably do agree on the philosophy, but we need to explain why instead of taking it as a given within our clique.

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