Brown Booby or Masked (file image) (1 Viewer)

[Deb Burhinus]

Following the putative Brown Booby sighting in Wales this week and again, the issue of confusion risks of adult BBs with immature Northern Gannet coming up, it occurred to me that immature Masked Booby (or even Nazca) might be more of a confusion risk with its white collar separating the brown neck from the shoulder, and from the side possibly giving the impression of a pale rump:

http://www.gobirding.eu/Photos/MaskedBooby.php

I came across this file image of a ‘Brown Booby’ but it looks like a Masked to me, can anyone confirm please?

https://www.countrylife.co.uk/news/...d-british-summer-corncrake-brown-booby-202628

Brown Booby
http://www.gobirding.eu/Photos/BrownBooby.php

Masked Booby is extremely rare in Europe (most of us will remember the Sea of Biscay ferry nearly 20yrs ago?!) but sympatric in much of its range with Brown Booby, the records of which are increasing, are the chances of Western Palaearctic records of this species also increasing and could one too easily be dismissed as an immature Northern Gannet with distant sea views?

Imm. Northern Gannet

http://www.gobirding.eu/Photos/Gannet.php

Of course decent views of the underwing too would avoid confusion with any of the boobies

 

[njlarsen]

I do not think that a truly adult brown B would be a risk for confusion with N Gannet, but the immature moulting birds might.

I do not have a lot of experience with Masked B, but BB should have the brown hood back to the front of the wing, and as such I also feel that the image you found looks more like a masked (unless it could be some weird runt individual of a gannet).

Niels

 

[Deb Burhinus]

I do not think that a truly adult brown B would be a risk for confusion with N Gannet, but the immature moulting birds might.

I do not have a lot of experience with Masked B, but BB should have the brown hood back to the front of the wing, and as such I also feel that the image you found looks more like a masked (unless it could be some weird runt individual of a gannet).

Niels

Thanks for the feedback Niels - I believe it’s only the imm. Masked Boobies that could present a confusion risk with imm. Gannets rather than adult or juvenile and as you say, adult Brown Boobies shouldn’t either with good views (although it has caused confusion with possible UK records when sea views/photographic evidence has been poor). The OP linked image is of an imm. Masked Booby I believe as here:

http://www.peruaves.org/sulidae/masked-booby-sula-dactylatra/

Even in imm Brown Boobys, the brown head and neck seems reaches the shoulder with no white collar

https://www.worldbirdphotos.com/photo/booby-brown-sula-leucogaster-immature-in-flight-polynesia-2/

I would be interested if anyone else has a view on the subject bird...and whether immature Brown Bobbies can also show this ‘white collar’? Thanks!

 

[Deb Burhinus]

For further underwing comparison between immature Masked and Brown Boobies and immature Gannets, David Appleton’s series of images are excellent - while distant sea views of the extent of brown on the neck of these immature birds varies and might be difficult to judge, distinctions in the underwing pattern might be more apparent

Masked Booby

https://www.gobirding.eu/Images/Sea... pelagic from Mirbat, 10-Nov-17 (A) (9) L.jpg

The dark brown flight feathers bordering extensive pale underwing coverts extending to pale base to primaries giving very contrasty underwing than either Brown Booby or Gannet with the dark carpal patch standing out cf to Gannet or Brown Booby

But the opposite pattern in Gannet with slightly paler flight feathers but mostly dark underwing impression with very dark coverts and pale axillaries :

https://www.gobirding.eu/Images/Seabirds/Gannet/Gannet, Scilly pelagic, 8-Aug-10 (28) L.JPG

https://www.gobirding.eu/Images/Seabirds/Gannet/Gannet, Scilly pelagic, 8-Aug-10 (5) L.JPG

Brown Booby

https://www.gobirding.eu/Images/Sea...ey West to Dry Tortugas, 20-Apr-13 (12) L.JPG

Less extensive white on the underwing with tips of coverts pale forming two underwing lines contrasting with darker base to wing, dark carpal patch, dark leading edge of patagium and pale axiliaries


Given the uncharacteristic lack of response for an ID question on BF, perhaps there are few people here with experience of these palagics so are not able to comment? I don’t have experience with these either but am keen to learn to eliminate confusion possibilities between Brown Boobies and other Boobies, given the recent records in Britain and Ireland, including the confusion I have with this file image ... so if any one can put my doubts to bed here?

https://www.countrylife.co.uk/news/...d-british-summer-corncrake-brown-booby-202628

 

[Dave Boyle]

A few years ago I used to see Brown Boobies & Masked Boobies pretty much every day for a couple of years - I can't really see there should ever be a problem identifying a Brown Booby in the field, in blurry photos there's clearly room for confusion with a Gannet but in the flesh there really shouldn't be

You are right though, an immature Masked Booby would be very easy to overlook as an immature Gannet & that photo you've linked looks like a Masked Booby to me

 

[Deb Burhinus]

Thanks Dave with your experience that’s very helpful indeed.

 

[birdmeister]

I think your original photo has got to be Masked too, Deb. Perhaps a case of just pulling the photo from somewhere, or was this actually photo'd in (or off the coast of) the UK?

 

[Deb Burhinus]

I think your original photo has got to be Masked too, Deb. Perhaps a case of just pulling the photo from somewhere, or was this actually photo'd in (or off the coast of) the UK?

Thanks ‘Birdmeister’.

The jpeg was likely purchased off the net - ie the researcher probably googled ‘Brown Booby’ for an image like I did but didn’t realise it was wrongly labelled and therefore the wrong species to illustrate the piece. (If it was taken in UK waters, it would have been the suppression of the century! )

 

[njlarsen]

You linked to some gobirding images that generally are quite good. But I do wonder about the identity of this bird; it looks wrong for a brown b to me: http://www.gobirding.eu/Images/Seab...Key West to Dry Tortugas, 20-Apr-13 (2) L.JPG

Niels

 

[Deb Burhinus]

You linked to some gobirding images that generally are quite good. But I do wonder about the identity of this bird; it looks wrong for a brown b to me: http://www.gobirding.eu/Images/Seab...Key West to Dry Tortugas, 20-Apr-13 (2) L.JPG

Niels

Yes, thanks. I may have inserted the wrong link - I had multiple windows open all of immature boobies and gannets, I posted the wrong links several times during the course of composing posts! I’ll have a look this evening on a better screen and when my internet isn’t so spotty.

 

[njlarsen]

I was talking about the first post where you linked to the general page for BB (this link: http://www.gobirding.eu/Photos/BrownBooby.php) and I am questioning one of the images from that page.

Niels

 

[birdmeister]

Thanks ‘Birdmeister’.

The jpeg was likely purchased off the net - ie the researcher probably googled ‘Brown Booby’ for an image like I did but didn’t realise it was wrongly labelled and therefore the wrong species to illustrate the piece. (If it was taken in UK waters, it would have been the suppression of the century! )

Thanks Deb. I guess I should have figured there'd be a firestorm if suppression was the case!

 

[Deb Burhinus]

I was talking about the first post where you linked to the general page for BB (this link: http://www.gobirding.eu/Photos/BrownBooby.php) and I am questioning one of the images from that page.

Niels

So I’m looking at these now on another larger monitor. Clearly on the Brown Booby page, the 5th image down and the one to the right of it are immature Northern Gannets. (I have now had the links removed where I referred to them in a later post to avoid confusion)

Another distinguishing feature that I’m seeing (which will be probably useless in the field but very helpful on good images) between boobies and gannets is the gular area. If you compare the structure of the bills/head of these two images referred to (5th pair) with Brown and Masked Booby (and probably all booby species), the gular angle in boobies points back from the rear of the eye and creates quite a wide angle (approx 45 degrees) forming a large gular pouch.

On Gannets, there is just sharp angle at the gape extending no further back behind the eye-and the depth of the bill is not so deep. Obviously too, the ‘tubenose’ on boobies extends further up the forehead to the rear of the eye and joins the forehead forming a smooth continuous line. Again, probably very difficult to see accurately on distant sea views.

 

[njlarsen]

So I’m looking at these now on another larger monitor. Clearly on the Brown Booby page, the 5th image down and the one to the right of it are immature Northern Gannets. (I have now had the links removed where I referred to them in a later post to avoid confusion)

Another distinguishing feature that I’m seeing (which will be probably useless in the field but very helpful on good images) between boobies and gannets is the gular area. If you compare the structure of the bills/head of these two images referred to (5th pair) with Brown and Masked Booby (and probably all booby species), the gular angle in boobies points back from the rear of the eye and creates quite a wide angle (approx 45 degrees) forming a large gular pouch.

On Gannets, there is just sharp angle at the gape extending no further back behind the eye-and the depth of the bill is not so deep. Obviously too, the ‘tubenose’ on boobies extends further up the forehead to the rear of the eye and joins the forehead forming a smooth continuous line. Again, probably very difficult to see accurately on distant sea views.

Thanks for confirming those images did not belong.

Regarding the part I bolded, Nice! I could see that gular pouch angle on my own images of Blue-foot, Red-foot and Nazca boobies.

Niels

 

[pbjosh]

Just another word to the original question - no doubt for me that the image is of a juvenile Masked or Nazca Booby. I assume it's a stock photo - the quality is ample to ID it to that species pair. ID'ing immatures of that pair is very difficult. I recall there are some details of upper tail coverts that look promising and are being cautiously used, though I'm not up to speed on it.

This is becoming quite an issue on the W Coast of N America where Boobies of several species are moving around more, expanding their ranges, etc. A lot of this is not well understood yet but it appears that Nazca Booby is becoming about as common as, if not more common than Masked Booby in California - and the first record of Nazca Booby wasn't even all that long ago - 2013 I think? I suppose it's quite likely Nazca Booby is breeding somewhere in Mexican territory in the Pacific.

Also interesting is the Northern Gannet that was (still is?) hanging around the Farallon Islands off the coast of San Francisco, which is thought to perhaps have made it to the Pacific due to opening of the NW passage in summer. On more than one occasion Brown or Blue-footed Boobies have made it to the bay area, and on more than one occasion day trips to the Farallons have ticked the Gannet, Brown, and BF Boobies all at once - any one of the 3 would have been an absolute mega 10-20 years ago. I think both Masked and Nazca Boobies have made it to the Farallons as well by now, but not sure about that.

 

[MJB]

This is becoming quite an issue on the W Coast of N America where Boobies of several species are moving around more, expanding their ranges, etc. A lot of this is not well understood yet but it appears that Nazca Booby is becoming about as common as, if not more common than Masked Booby in California - and the first record of Nazca Booby wasn't even all that long ago - 2013 I think? I suppose it's quite likely Nazca Booby is breeding somewhere in Mexican territory in the Pacific.

The northern end of San Benedicto?
MJB

 

[pbjosh]

The northern end of San Benedicto?
MJB

Indeed, I should have done some digging before assuming they weren't already known to breed on not just one but two Mexican Islands - San Benedicto and Clipperton. Incidentally a brief look suggests that these are the two locations where Masked is breeding in the tropical NE Pacific as well.

Still though, I don't think anyone has a good explanation beyond "maybe global warming, maybe population increases, or maybe new colonies" to explain why Nazca has gone from no records to the expected black-and-white Booby. Nazca has actually been reliable in and around Silver Strand and the south bay area in San Diego in the past couple years as I understand it.

 

[Deb Burhinus]

Just another word to the original question - no doubt for me that the image is of a juvenile Masked or Nazca Booby. I assume it's a stock photo - the quality is ample to ID it to that species pair. ID'ing immatures of that pair is very difficult. I recall there are some details of upper tail coverts that look promising and are being cautiously used, though I'm not up to speed on it.

This is becoming quite an issue on the W Coast of N America where Boobies of several species are moving around more, expanding their ranges etc ...

Hi pbjosh

Further to yet another sighting of Brown Booby off the coast of Cornwall, UK in the past few days:

Thank you for your comments on the original ID query but also your remarks regarding Nazca Boobies. I noted (and quickly skipped!) the potential confusion with this species and imm Northern Gannet in my first post on this thread - (one confusion Booby species seemed enough) as I did not realise they too were under going shifting patterns of global movement.

However, since you raised the separation difficulties between Masked and Nazca Booby, I thought it merited further discussion (most birders enjoy a good identification challenge). Given your thoughts as to the increasing extra-limital records vis a vis AGW (anthropomorphic global warming), population changes/dispersal of Boobies (and Northern Gannet!), and also given its sympatric nature with Masked Booby, I agree Nazca should be part of any discussion where confusion situations could present themselves. I too considered the potential impact of AGW on future records of Booby species in UK waters when reports of vagrant Brown Boobies started apparently increasing. It would be very interesting to track the route of their journey into UK waters given their propensity for nearer off shore feeding cf to some palagics.

After googling hundreds of online images of immature Masked and Nazca Boobies looking at ways to separate them, I began to see bill colour as a possible criteria along with the central retrices you mentioned earlier. I then googled ‘bill’ colour as identification criteria for these two species and came across an excellent paper (which you may have already read) which contains some good photographic illustrations also

https://www.birdpop.org/docs/pubs/Pyle_2020_Molt_Age_and_ID_of_MABO_and_NABO.pdf


From the second plumage cycle (prebasic) (at around 17-22 months) of these immatures, it seems the bill colour of Nazca and Masked becomes a fairly reliable separation character - only ‘fairly’ as there is as always with these things a small degree of overlap and intra-specific variation. There are reported, from the studies carried out, of colour combinations that are expressed as a prediction of adult bill colour in each species. A weakness of the scientific data however lies in the studies focussed on one geographical population. It could be that other populations have no phenotypical differences and/or environmental factors/diet determine bill colour variation rather than genotypical differences between Masked and Nazca species.

Also, the criteria of central retrix colour that you referrred to earlier is also discussed which would certainly be helpful in the field if that were to gain established and proven reliability. I’ve not been able to find any reliable images for separating the underwing pattern of these immature birds and the bill colour again, as a distant sea view criteria, will remain largely inadequate.

Nazca

https://www.oiseaux.net/photos/francoise.folliard/nazca.booby.5.html

www.slrobertson.com/galleries/south...ls/galapagos-birds/juvenile-nazca-booby-6.htm

more thoughts on bill colour

http://www.sandiegobirding.com/?p=5340

Masked Booby

https://ebird.org/media/catalog?taxonCode=masboo&regionCode=&mediaType=p

I’ve not checked all the above links (especially ebirds) for accuracy so if anyone sees any that have been wrongly identified ...?

 

[njlarsen]

Now you mention bill color of boobies: Brown B differs in bill color in Australia vs Caribbean. It would not be unreasonable to expect other species to differ as well. The small range of Nazca as currently understood (if I understand correctly) helps.

Niels