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Oceanodroma monorhys at Portugal

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Old Saturday 16th May 2020, 15:27   #1
Marcio Cachapela
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Oceanodroma monorhis at Portugal

Hello all
I saw this bird at Cabo Raso, near Cascais, Portugal, at 15/05/2020.
It was flying with a flock of Hydrobates pelagicus and i saw the bird a few minutes.
It was a bird with no white on uperparts or wing, it was bigger than Hydrobates pelagicus and the flight was fast and more straight, not "nervous" like Hydrobates flight.
Pics are not the best because the bird was far away. There are two pics with a gull near and a Hydrobates pelagicus to compare sizes.
It seems a Oceanodroma monorhys, and after ask some opinions, some people thinks the same, but i would like a few more opinions, as it would be a rarity at Portugal mainland and one of the few records.

Thanks in advance
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Old Saturday 16th May 2020, 17:35   #2
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Hi Marcio,
you spelled the name wrong which means you don't get any search results, it's monorhis!

Anyway, definitely looks like it could be Swinhoe's Petrel?
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Old Saturday 16th May 2020, 17:55   #3
Marcio Cachapela
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Quote:
Originally Posted by andyadcock View Post
Hi Marcio,
you spelled the name wrong which means you don't get any search results, it's monorhis!

Anyway, definitely looks like it could be Swinhoe's Petrel?
Thanks... i spelled the name wrong at this thread you are right. But it is rare at Portugal anyway, would be the third record at Portugal mainland.
But your setence is a afirmation not a question right?
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Old Saturday 16th May 2020, 19:10   #4
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Certainly looks a good possibility. I won't try to weigh in as an expert, I've not seen Swinhoe's and haven't studied it ever, really. I don't think there's much doubt it's an all-dark mid to large sized Storm-Petrel. Certainly Swinhoe's should be the most logical answer, a great record no doubt.
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Old Saturday 16th May 2020, 21:00   #5
Marcio Cachapela
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Originally Posted by pbjosh View Post
Certainly looks a good possibility. I won't try to weigh in as an expert, I've not seen Swinhoe's and haven't studied it ever, really. I don't think there's much doubt it's an all-dark mid to large sized Storm-Petrel. Certainly Swinhoe's should be the most logical answer, a great record no doubt.
Thanks for your opinion
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Old Saturday 16th May 2020, 22:02   #6
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I have no experience with this species but want to bring up something I just read (Howell). In the Atlantic there are supposed to be some Leach's storm petrel that have so little white on the upperside that it looks all dark under at sea conditions. Swinhoe's is supposed to be recognizable from those by exposed white shafts in outer primaries if one gets close enough to see this.

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Old Saturday 16th May 2020, 22:27   #7
Marcio Cachapela
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Quote:
Originally Posted by njlarsen View Post
I have no experience with this species but want to bring up something I just read (Howell). In the Atlantic there are supposed to be some Leach's storm petrel that have so little white on the upperside that it looks all dark under at sea conditions. Swinhoe's is supposed to be recognizable from those by exposed white shafts in outer primaries if one gets close enough to see this.

Niels
Thanks for your opinion. I had another one where it was told that the wing format was wrong for Leach's storm petrel, and the bird flight was wrong aswell.
But thanks again.
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Old Sunday 17th May 2020, 10:23   #8
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Quote:
Originally Posted by njlarsen View Post
I have no experience with this species but want to bring up something I just read (Howell). In the Atlantic there are supposed to be some Leach's storm petrel that have so little white on the upperside that it looks all dark under at sea conditions. Swinhoe's is supposed to be recognizable from those by exposed white shafts in outer primaries if one gets close enough to see this.

Niels
I know this always gets brought up in conversations about dark-rumped petrels in the North Atlantic, but doesn't the evidence suggest that such aberrant Leach's Petrels are vanishingly rare?
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Old Sunday 17th May 2020, 10:49   #9
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I know this always gets brought up in conversations about dark-rumped petrels in the North Atlantic, but doesn't the evidence suggest that such aberrant Leach's Petrels are vanishingly rare?
Not sure how vanishingly rare, but Swinhoe's are rare too ...
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Old Sunday 17th May 2020, 11:04   #10
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Not sure how vanishingly rare, but Swinhoe's are rare too ...
Not so rare that they don't turn up in ringers nets in the NE of Engalnd, not sure they try to catch them anymore though?
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Old Sunday 17th May 2020, 11:10   #11
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There was a post/image of skins I think I recall ones showing some Leach's with reduced white in the rump - not sure if all black or not, but a range of restriction at any rate.

Not sure if it could be accepted on these photos, but different flight style etc was noted above.
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Old Sunday 17th May 2020, 11:12   #12
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Quote:
Originally Posted by dantheman View Post
There was a post/image of skins I think I recall ones showing some Leach's with reduced white in the rump - not sure if all black or not, but a range of restriction at any rate.

Not sure if it could be accepted on these photos, but different flight style etc was noted above.
I'd be very surprised if it was, it will surely go down as a 'Dark rumped Petrel sp'.

It's a perfect illustration of why I don't seawatch, the OP, in my limited experience, is the typical view of anything you see!
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Old Sunday 17th May 2020, 12:11   #13
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Originally Posted by dantheman View Post
Not sure how vanishingly rare, but Swinhoe's are rare too ...
There's a paper online somewhere, from memory one specimen with an all dark rump, a few with reduced white probably related to late-summer wear. Swinhoe's is rare, but pretty much annual in WP waters. It seems to be the equivalent of the runt Manx theory!
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Old Sunday 17th May 2020, 12:17   #14
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There's a paper online somewhere, from memory one specimen with an all dark rump, a few with reduced white probably related to late-summer wear. Swinhoe's is rare, but pretty much annual in WP waters. It seems to be the equivalent of the runt Manx theory!
Disagree slightly - runt Manxies essentially completely unproven I think?, not sure the same can be said for darker rumped Leaches, but yes agree Swinhoe's are out there.

Caution and all that, but if I'd seen it I wouldn't want people invoking 'possible other scenarios' it is fair to say. Nice one for the observers in any case
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Old Sunday 17th May 2020, 13:57   #15
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Originally Posted by njlarsen View Post
In the Atlantic there are supposed to be some Leach's storm petrel that have so little white on the upperside that it looks all dark under at sea conditions.
I read it in several books. But I never heard about anybody actually seeing an example.

Perhaps somebody could dig out the original source of this claim. It is even possible that the original 'Leach's petrel with black rump' was misidentified Swinhoe's.
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Old Sunday 17th May 2020, 14:41   #16
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https://britishbirds.co.uk/wp-conten...02_N7_3_23.pdf - article by Bob Flood on Leach's rump variation.
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Old Sunday 17th May 2020, 16:34   #17
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https://britishbirds.co.uk/wp-conten...02_N7_3_23.pdf - article by Bob Flood on Leach's rump variation.
Thanks, that was the article I was thinking of.
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Old Sunday 17th May 2020, 23:16   #18
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Thanks for all opinions!
So, even with this bad pics the higher probability would be Oceanodroma monorhis?
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Old Monday 18th May 2020, 01:58   #19
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Hello Márcio,

obviously, this is a very interesting record. I can imagine it got your heart pumping. I've been avoiding to comment on this thread, but I guess it can't do much harm.

I do have some experience with this species, but ironically probably it doesn't put me in a much better place to comment than the ones that already commented above, as I'll explain next (it includes some unnecessary detail, but perhaps it'll be interesting to read).

Over several years (2007-2009) I've found around 10 Swinhoe's Storm Petrels in the Selvagens Islands (all in Selvagem Grande), some of them perhaps the same over several years and many were recorded several times in each year. These were all found due to very solitary night work specifically directed at this species, covering all of the island surface. I found the first (the one in plate 210 of the above linked paper) following indications from Frank Zino, but all of the following were the result of perseverance. It involved mostly listening, although some were captured either in mist nests or inside easily accessible burrows; others just flew over, calling, and others were inside inaccessible burrows; at one point I found a male and a female together inside one burrow but these were only sound recorded (males and females have different calls: the pitch is different). They can actually be considered to be expected there, in my opinion. Despite all my efforts I never managed to confirm they were breeding there, and my data seems to suggest they are actually not (somewhat surprisingly, for me), at least not regularly: they do congregate there though. The biggest difficulty involved with finding them by sound there is because the island harbours a massive Cory's Shearwater colony (40k pairs?) and on most nights the sound of their calls/song is basically deafening; on some nights though (due to their cycle) it gets more silent and it makes the task more possible.
Some of the details were published here: https://www.researchgate.net/publica...e_Hydrobatinae

So, despite having had quite a few in the hand and having heard it "frequently", I have no experience with this species at sea at all, which is what this record is all about.

My perception/experience is thus a bit biased, but of course in terms of probability, there's nothing against it being monorhis. The species "must be around", and birds being found in the British Isles and elsewhere to the north might pass on Portuguese waters. There have been also records from around Madeira and the Azores. However, assessing a record of a rarity has little to do with probabilities (although these are also taken into account) and more about concrete evidence that is presented (I'm imagining you'd want to submit this record).

From your short description and photos, the bird is clearly an Oceanodroma. There have been records of all dark small petrels on the Portuguese coast (mainland) in the past, with only some of those being submitted to the Portuguese Rarities Committee; none has ever been accepted. Usually people had trouble to rule out Bulweria on their descriptions, either because they had no previous experience of the species or because they had not seen enough detail. This aspect is resolved in your observation: the bird is a clear Oceanodroma.

Now you'd want to see what evidence can be extracted from the photos that can rule out some species and confirm your ID (basically those included in the Bob Flood's paper, above); one thing that people sometimes forget when submitting a record with photos is that supplementary information, as detailed as possible, can and should be included, in order to explain the photos presented (e.g. are they showing the upperparts or the underparts? etc) and to complement that visual information, focusing on all that is not possible to extract from those pics but that you actually saw in the field. In this case you shortly described the flight action, but perhaps you can add some more detail (that you actually saw and remember).
You mentioned that someone said that wings were not Leach's S-Petrel like; I'm not sure you can say that from such photos, it's tricky and a bit wishful thinking: remember that a photo always captures a fraction of a second and many times less than typical shapes are captured. My experience of the species at sea comes from seeing videos of it, and from those the shape on your photos seems ok.
Of your 5 photos, I believe only pic 3 shows the upperparts? But I'm not 100% sure of this. If yes, the bird seems to have all dark upperparts (but a closer inspection could change this, the photo resolution is really low); it's here that it's important to provide additional info, explaining (if this is the case) that you confirmed the colouration while watching the bird.
On the remaining 4 pics it's possible to see a slightly paler underwing band, which is ok for Swinhoe's. On some pics there's a suggestion of a slightly paler head, which is also good.
The thing is not so much what you can see on your photos (nothing of which rules out Swinhoe's), it's more about the diagnostic features that you cannot see there (pale primary quills, exact colours and patterns, tail shape, etc).
It looks good to me, in terms of "probabilities" you are also ok (it would be more extraordinary to find any of the confusion possibilities), and I think it most likely is one. But in the end, for it to be accepted (by the rarities committee, if that's what you're aiming at) it will come down to the individual opinions of the committee members (I'm not there anymore, otherwise I definitely would not comment here), so who knows. I hope this helps, somehow.
And of course, congratulations for the find, it's a crazy species to see from land!
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Old Tuesday 19th May 2020, 10:40   #20
Marcio Cachapela
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Originally Posted by RafaelMatias View Post
Hello Márcio,

obviously, this is a very interesting record. I can imagine it got your heart pumping. I've been avoiding to comment on this thread, but I guess it can't do much harm.

I do have some experience with this species, but ironically probably it doesn't put me in a much better place to comment than the ones that already commented above, as I'll explain next (it includes some unnecessary detail, but perhaps it'll be interesting to read).

Over several years (2007-2009) I've found around 10 Swinhoe's Storm Petrels in the Selvagens Islands (all in Selvagem Grande), some of them perhaps the same over several years and many were recorded several times in each year. These were all found due to very solitary night work specifically directed at this species, covering all of the island surface. I found the first (the one in plate 210 of the above linked paper) following indications from Frank Zino, but all of the following were the result of perseverance. It involved mostly listening, although some were captured either in mist nests or inside easily accessible burrows; others just flew over, calling, and others were inside inaccessible burrows; at one point I found a male and a female together inside one burrow but these were only sound recorded (males and females have different calls: the pitch is different). They can actually be considered to be expected there, in my opinion. Despite all my efforts I never managed to confirm they were breeding there, and my data seems to suggest they are actually not (somewhat surprisingly, for me), at least not regularly: they do congregate there though. The biggest difficulty involved with finding them by sound there is because the island harbours a massive Cory's Shearwater colony (40k pairs?) and on most nights the sound of their calls/song is basically deafening; on some nights though (due to their cycle) it gets more silent and it makes the task more possible.
Some of the details were published here: https://www.researchgate.net/publica...e_Hydrobatinae

So, despite having had quite a few in the hand and having heard it "frequently", I have no experience with this species at sea at all, which is what this record is all about.

My perception/experience is thus a bit biased, but of course in terms of probability, there's nothing against it being monorhis. The species "must be around", and birds being found in the British Isles and elsewhere to the north might pass on Portuguese waters. There have been also records from around Madeira and the Azores. However, assessing a record of a rarity has little to do with probabilities (although these are also taken into account) and more about concrete evidence that is presented (I'm imagining you'd want to submit this record).

From your short description and photos, the bird is clearly an Oceanodroma. There have been records of all dark small petrels on the Portuguese coast (mainland) in the past, with only some of those being submitted to the Portuguese Rarities Committee; none has ever been accepted. Usually people had trouble to rule out Bulweria on their descriptions, either because they had no previous experience of the species or because they had not seen enough detail. This aspect is resolved in your observation: the bird is a clear Oceanodroma.

Now you'd want to see what evidence can be extracted from the photos that can rule out some species and confirm your ID (basically those included in the Bob Flood's paper, above); one thing that people sometimes forget when submitting a record with photos is that supplementary information, as detailed as possible, can and should be included, in order to explain the photos presented (e.g. are they showing the upperparts or the underparts? etc) and to complement that visual information, focusing on all that is not possible to extract from those pics but that you actually saw in the field. In this case you shortly described the flight action, but perhaps you can add some more detail (that you actually saw and remember).
You mentioned that someone said that wings were not Leach's S-Petrel like; I'm not sure you can say that from such photos, it's tricky and a bit wishful thinking: remember that a photo always captures a fraction of a second and many times less than typical shapes are captured. My experience of the species at sea comes from seeing videos of it, and from those the shape on your photos seems ok.
Of your 5 photos, I believe only pic 3 shows the upperparts? But I'm not 100% sure of this. If yes, the bird seems to have all dark upperparts (but a closer inspection could change this, the photo resolution is really low); it's here that it's important to provide additional info, explaining (if this is the case) that you confirmed the colouration while watching the bird.
On the remaining 4 pics it's possible to see a slightly paler underwing band, which is ok for Swinhoe's. On some pics there's a suggestion of a slightly paler head, which is also good.
The thing is not so much what you can see on your photos (nothing of which rules out Swinhoe's), it's more about the diagnostic features that you cannot see there (pale primary quills, exact colours and patterns, tail shape, etc).
It looks good to me, in terms of "probabilities" you are also ok (it would be more extraordinary to find any of the confusion possibilities), and I think it most likely is one. But in the end, for it to be accepted (by the rarities committee, if that's what you're aiming at) it will come down to the individual opinions of the committee members (I'm not there anymore, otherwise I definitely would not comment here), so who knows. I hope this helps, somehow.
And of course, congratulations for the find, it's a crazy species to see from land!
Thanks for your opinion Rafael.
Yes im thinking in submit this record to CPR but i needed some opinions first because my lack of experience with these kind of species and bad pics.
In these cases i think that it is important to observe the flight patern and as i understood that would be hard to take any kind of quallity pics i paid more attention to it.
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