Ravens predating Little Egret colony (1 Viewer)

devon.birder · Nov 20, 2005

According to the Brownsea Island Nature Reserve report in the Dorset Bird Club Newsletter the Island's pair of Ravens are eating Little Egrets.
A record number of Little Egrets bred in 2005, 49 pairs counted in May and June but not a single young fledged. Apparently the Islands's single pair of Ravens fledged three young at this time and whilst in previous years they have foraged for food on the mainland this year was different. After predating the contents of about 10 Oystercatchers' nests located around the seawall they turned their attentions to the Little Egret colony. The remains of at least 12 dead young and 2 dead adults were found on the ground underneath the nests.
Fortunately the Ravens did not raid the nests of almost 500 Terns which also nest on the Island although productivity was poor due to predation by gulls, Herons, crows and Rats.
The advice of the RSPB has been sought to see if there are any appropriate measures that could be taken to avoid a repetition next year.
Ravens certainly seem to have increased in the South West and I regularly now see them flying over my house in Tiverton. This is the first time though that I have read about them killing a bird the size of a Little Egret.
The Report also says that Little Egrets first bred on Brownsea Island in 1966 but I would think that has to be a miss print. Roger

Amarillo · Nov 21, 2005

devon.birder said:
The Report also says that Little Egrets first bred on Brownsea Island in 1966 but I would think that has to be a miss print. Roger

Yes, it was 1996.

Shocking news about the nest predation.

devon.birder · Nov 21, 2005

Amarillo said:
Yes, it was 1996.

Shocking news about the nest predation.

Thanks Amarillo, I thought it must have been an error. When I saw my first Little Egret on St Agnes, Isles of Scilly in the early 1970s it was a major rarity.
I suppose the easy answer to the Raven problem on Brownsea would be to shoot them as Terns need all the support they can get. Perhaps the RSPB will suggest trapping them and relocating them a long way away. We will have to wait and see. Roger

Amarillo · Nov 21, 2005

devon.birder said:
I suppose the easy answer to the Raven problem on Brownsea would be to shoot them as Terns need all the support they can get. Perhaps the RSPB will suggest trapping them and relocating them a long way away. We will have to wait and see. Roger

Its a difficult one. You could argue that nature should be left alone, but on the other hand nothing is truly natural anymore so in times like this we should step in (and shoot the ravens)

John P · Nov 21, 2005

It's sometimes hard to believe what you read on here. :-C

It seems that any problem with the Terns on Brownsea was caused by everything else except the Ravens and yet you want to shoot them.

Brownsea is only 20 miles from me and yet I'm not allowed to mention Ravens on my local e-mail birdlist because of their rarity in area.

Little egrets on the other hand are almost ten-a-penny around here.

Amarillo · Nov 21, 2005

John P said:
It's sometimes hard to believe what you read on here. :-C

It seems that any problem with the Terns on Brownsea was caused by everything else except the Ravens and yet you want to shoot them.

Brownsea is only 20 miles from me and yet I'm not allowed to mention Ravens on my local e-mail birdlist because of their rarity in area.

Little egrets on the other hand are almost ten-a-penny around here.

I think you misunderstand me. I merely pointed out the two sides to the argument. I don't know enough about this problem on Brownsea to give an informed opinion.

Strandman · Nov 21, 2005

Amarillo said:
I think you misunderstand me. I merely pointed out the two sides to the argument. I don't know enough about this problem on Brownsea to give an informed opinion.

I'm not at all squeamish about predator control, but don't like the idea of taking out some recolonising Ravens. Might be a case for supplemental feeding of the Ravens to keep them busy elsewhere during the breeding season. But that's hardly a long-term solution.

As for the long-term, L Egrets may ahve to wise-up and find a Grey Heronry (assuming this isn't one) where they will be safer from predators.

Silvershark · Nov 21, 2005

devon.birder said:
Thanks Amarillo, I thought it must have been an error. When I saw my first Little Egret on St Agnes, Isles of Scilly in the early 1970s it was a major rarity.
I suppose the easy answer to the Raven problem on Brownsea would be to shoot them as Terns need all the support they can get. Perhaps the RSPB will suggest trapping them and relocating them a long way away. We will have to wait and see. Roger

It said in the article that the Ravens DID NOT predate the nests of the terns, with 500 (pairs?) terns I think that numbers would offer a fair bit of protection from ravens and predation of nests and birds should be able to be absorbed. Little egrets are a new coloniser to the UK, moving in through natural means, ravens are recolonising areas where they were driven away by the actions of people and I would not like to see a repeat performance of that. Little egrets will face predators such as ravens on their range expansion, but in my opinion this should be left to nature. They are not a species that were driven out by people, persecuting one that was for a new coloniser that is actually doing well in gaining a foothold so far I personally think would be wrong. The only animal disturbance to the Little Egrets that should be limited, is disturbance from people.

devon.birder · Nov 21, 2005

Silvershark said:
It said in the article that the Ravens DID NOT predate the nests of the terns, with 500 (pairs?) terns I think that numbers would offer a fair bit of protection from ravens and predation of nests and birds should be able to be absorbed. Little egrets are a new coloniser to the UK, moving in through natural means, ravens are recolonising areas where they were driven away by the actions of people and I would not like to see a repeat performance of that. Little egrets will face predators such as ravens on their range expansion, but in my opinion this should be left to nature. They are not a species that were driven out by people, persecuting one that was for a new coloniser that is actually doing well in gaining a foothold so far I personally think would be wrong. The only animal disturbance to the Little Egrets that should be limited, is disturbance from people.

It will be interesting to see what the RSPB will recommend for the Brownsea Ravens. As I stated in my original post the Ravens did not predate the Tern colonies this year so it may be a case of wait and see.
The report by the Brownsea Reserve Warden also mentioned that on the night of the 11 June a number of Cormorants were disturbed from thier usual roosting site and decided to roost on two of the Sandwich Tern nesting islands. In a matter of a few hours they trampled 70 nests. This colony still managed to fledge approximately 115 young though. It is a pity that he did not say what the cause of the disturbance was. Roger

Robin Pearson · Nov 22, 2005

I take it the warden did actually see the newly fledged ravens attacking the egret colony or has some other from of proof? I too find it hard to believe an immature raven taking on an adult egret though having witnessed juvenile magpies attacking anything that moves in my garden I suppose anything is possible.

To me the description of the attacks has all the hallmarks of a fox, which is capable of climbing trees to get at a nest providing the trees are reasonably easy to climb.

Short of repatriating the ravens to the mainland the idea of feeding them during the breeding season seems a good idea, why not put out a few dead rabbits to distract them from the nesting sites.

devon.birder · Nov 22, 2005

Robin Pearson said:
I take it the warden did actually see the newly fledged ravens attacking the egret colony or has some other from of proof? I too find it hard to believe an immature raven taking on an adult egret though having witnessed juvenile magpies attacking anything that moves in my garden I suppose anything is possible.

To me the description of the attacks has all the hallmarks of a fox, which is capable of climbing trees to get at a nest providing the trees are reasonably easy to climb.

Short of repatriating the ravens to the mainland the idea of feeding them during the breeding season seems a good idea, why not put out a few dead rabbits to distract them from the nesting sites.

The warden does not actually state in the report that the Ravens were seen predating the nests but Brownsea Island is a small island and as he stated that they didn't predate the tern colonies it is pretty safe to assume that it was known beyond doubt that the Ravens were the culprits. Are there any foxes on Brownsea?.
He does say that watching the 5 Ravens, 2 adults and 3 young systematically working their way around the seawall searching every nook and cranny for something to eat was both very disturbing and interesting.
240 pairs of Common Terns and 248 pairs of Sandwich Terns nest on Brownsea. Roger

devon.birder · Nov 22, 2005

Whilst looking at the Black Grouse UK web site I noticed the following statement: "Ravens also occur in black grouse areas, and it is illegal to trap or kill them, or to destroy their nests or eggs". It looks like the Warden at Brownsea Island may have a problem.
Roger

Jos Stratford · Nov 22, 2005

As Little Egrets are an expanding colonist to UK shores, a very welcome one in my opinion, they will just have to live with the local Ravens ...if they can't hack the predators, then they don't get to continue their expansion, simple as that. Somehow, don't think their expansion is going to be halted by the Ravens and it is a wrong move to start exterminating the Ravens

Silvershark · Nov 22, 2005

devon.birder said:
Whilst looking at the Black Grouse UK web site I noticed the following statement: "Ravens also occur in black grouse areas, and it is illegal to trap or kill them, or to destroy their nests or eggs". It looks like the Warden at Brownsea Island may have a problem.
Roger

What problem? They have not, as has been stated, preyed upon the tern nests and as I said even if they did the tern numbers should be enough of a buffer to absorb any impact. The only birds they have prey on are the little egrets who's spread will undoubtedly continue with or without the ravens, and if they don't then that is nature. To persecute the ravens when they have done nothing would be wrong and senseless. Nothing in this thread so far is a valid reason to do anything to the ravens at Brownsea Island.

devon.birder · Nov 22, 2005

Silvershark said:
What problem? They have not, as has been stated, preyed upon the tern nests and as I said even if they did the tern numbers should be enough of a buffer to absorb any impact. The only birds they have prey on are the little egrets who's spread will undoubtedly continue with or without the ravens, and if they don't then that is nature. To persecute the ravens when they have done nothing would be wrong and senseless. Nothing in this thread so far is a valid reason to do anything to the ravens at Brownsea Island.

Possibly not at present but in 10 years time when there could be a large Raven colony on Brownsea and few if any other breeding birds then it could be too late. Brownsea Island is privately owned and I presume is to some extent reliant on people visiting the island for income. I just wonder whether or not this will influence their decision whatever they decide to do. Who knows.
Just down the Dorset coast at Chesil Bank the Little Tern colony had their worst ever breeding season and this time the culprits were probably foxes. One was actually caught on camera predating an Oystercatcher's nest. I would think that this colony will have gone within 5 years if drastic action is not taken soon. Roger

Silvershark · Nov 22, 2005

devon.birder said:
Possibly not at present but in 10 years time when there could be a large Raven colony on Brownsea and few if any other breeding birds then it could be too late. Brownsea Island is privately owned and I presume is to some extent reliant on people visiting the island for income. I just wonder whether or not this will influence their decision whatever they decide to do. Who knows.
Just down the Dorset coast at Chesil Bank the Little Tern colony had their worst ever breeding season and this time the culprits were probably foxes. One was actually caught on camera predating an Oystercatcher's nest. I would think that this colony will have gone within 5 years if drastic action is not taken soon. Roger

Could be, might be, maybe there is no way of knowing that there will be a "large" raven colony and what impact they would have on the terns. It would be senseless taking action against something that "might happen" in the future when there is no evidence to suggest that may be the case. With the increase in the tern colony the predators will obviously follow but this is a natural order. Where there is prey, they will be predators it is something that should be accepted. The terns will not be unaccustomed to predators, and should the ravens in the future turn to the terns as prey the turns will have their methods of defending their chicks and nests. As I have previously said, tern numbers at the current time are likely to be a buffer. In 10 years time, the tern numbers should be even higher and therefore able to withstand the impact of ravens should they start to prey on the nests. It is highly unlikely that the ravens will exceed the numbers that their prey can support and cause any major problems - of course perhaps you (or somneone else) can give some evidence where this has occurred elsewhere specifically between ravens and terns.

hil5 · Nov 22, 2005

a kestrel was shown to affect a local chick population of little terns recently:

http://new.edp24.co.uk/content/news...gory=news&itemid=NOED07 Sep 2005 17:45:35:830

Predator control does go on on RSPB reserves of crows, foxes, black-headed gulls etc. Although I don't think ravens should be controlled as they are rarer than egrets there.

devon.birder · Nov 22, 2005

Silvershark said:
Could be, might be, maybe there is no way of knowing that there will be a "large" raven colony and what impact they would have on the terns.

Just about everything we write on Bird Forums is pure speculation and in the end will make absolutely no difference whatsoever. Roger

stevo2 · Nov 23, 2005

devon.birder said:
Brownsea Island is privately owned and I presume is to some extent reliant on people visiting the island for income. I just wonder whether or not this will influence their decision whatever they decide to do. Who knows.

Brownsea Island is a National Trust property, and the nature reserve around the lagoon is leased to and run by the Dorset Wildlife Trust. Both organisations, in common with most conservation bodies, are reliant on public donations. And yes, both charge (non members) for entrance to the island. But they are both highly responsible organisations with a wealth of conservation experience, and are unlikely to take any course of action without a thorough assessment of the ecological consequences. I doubt they would embark on an illegal raven cull wihtout running it by English Nature first.

For what it's worth, I visited Brownsea this June, a day or two after half of the Sandwich Tern nests were wiped out in the space of a single weekend. The only birds I saw nest-robbing were Great Black-Backed gulls.

Steve

http://www.siblog.co.uk/
http://www.siblingmedia.com/

James Blake · Nov 23, 2005

Jos Stratford said:
As Little Egrets are an expanding colonist to UK shores, a very welcome one in my opinion, they will just have to live with the local Ravens ...if they can't hack the predators, then they don't get to continue their expansion, simple as that.

Yep, agree with that.

James

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