Join for FREE
It only takes a minute!
Zeiss - Always on the lookout for something special – Shop now

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Fea's Petrel - Cape Verde (off Sao Nicolau) - April 2013

Reply
 
Thread Tools Rate Thread
Old Wednesday 19th September 2018, 22:37   #1
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
Fea's Petrel - Cape Verde (off Sao Nicolau) - April 2013

OK - definitely stopped playing with historic photos now. Never been a meatloaf fan so dug out some Fea's Petrels photos - the third North Atlantic pterodroma taxon. Identical to Desertas? First four are Fea's (April 2013) and the last is a Desertas (from July 2018).

Answers on a postcard............

http://www.rarebirdalert.co.uk/v2/Co...s_id=243825688

All the best

Paul
Attached Thumbnails
Click image for larger version

Name:	138 Fea's Petrel Raso Boat Trip.JPG
Views:	50
Size:	108.4 KB
ID:	674808  Click image for larger version

Name:	139 Fea's Petrel Raso Boat Trip.JPG
Views:	51
Size:	109.9 KB
ID:	674809  Click image for larger version

Name:	140 Fea's Petrel Raso Boat Trip.JPG
Views:	55
Size:	76.9 KB
ID:	674810  Click image for larger version

Name:	141 Fea's Petrel Raso Boat Trip.JPG
Views:	36
Size:	71.1 KB
ID:	674811  Click image for larger version

Name:	Pterodroma Desertas 1(4).JPG
Views:	69
Size:	179.2 KB
ID:	674812  

__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.
Paul Chapman is offline  
Reply With Quote
Old Wednesday 19th September 2018, 22:40   #2
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
A couple of articles to read to answer the question - what taxon(s) do we get?

All the best

Paul
Attached Files
File Type: pdf V99_N08_P404_419_A003.pdf (713.2 KB, 19 views)
File Type: pdf srep23447.pdf (1.42 MB, 22 views)
__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.
Paul Chapman is offline  
Reply With Quote
Old Thursday 20th September 2018, 09:33   #3
Muppit17
Registered User

 
Join Date: Apr 2017
Location: Hampshire
Posts: 97
Quote:
Originally Posted by Paul Chapman View Post
A couple of articles to read to answer the question - what taxon(s) do we get?

All the best

Paul
Ok Paul, I'm going to play the game. Having seen Desertas off Desertas in July I am fairly sure I have seen Desertas.

The whole rest of the information seems to be based upon conjecture. I am not doubting anything that has been written but logically the arguments are hypothesis that remain to be proven.

You say that you know that your photos from Cape Verde are Fea's. Yet the text says that Desertas in non-breeding range to Cape Verde. Did you identify on range, and if so how can anyone separate non-breeding wandering Desertas from 'resident' Fea's?

If for breeding, as suggested, Desertas is closely placed to Desertas/Madeira, why do we get a peak of records from sea watching in August/September. They shouldn't be there - unless these are non-breeding birds perhaps? (is this just a reflection of observer activity rather than number of birds?)

What do we know of the development of plumage and size. We know they are sexually dimorphic and there is overlap in size and bulk between species but can anyone sex birds in the field (or should I say rocking boat?). What about ageing birds?

It feels to me that this is one of the great ID challenges at the moment (up there with Band-rumped/Madeiran Storm Petrel - I gave up off Hatteras with Patteson crew - there were definitely differences but no idea what they meant).

The text suggests we should get Zino's - has anyone claimed one yet? All photos I have seen have the thick bill and heavy appearance of the Desertas/Fea's pair.

Last edited by Muppit17 : Thursday 20th September 2018 at 11:43.
Muppit17 is offline  
Reply With Quote
Old Thursday 20th September 2018, 10:20   #4
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
Thank you very much for coming to play. I hoped someone would!

Just to say, I'll look tonight as I am at work currently.

(I've changed my mind on these several times as to what I think is most likely....)

All the best
__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.
Paul Chapman is offline  
Reply With Quote
Old Thursday 20th September 2018, 21:15   #5
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
In answer quickly to your points:-

1. The Fea’s Petrels were solely identified on range so probability. As you indicate, the last week of April is within the breeding period of Fea’s Petrel (population 500 pairs) and right at the end of the non-breeding period for Desertas Petrel (160-180 pairs). So whilst Desertas Petrel does occur in the Cape Verdes outside the breeding season, surely the combination of timing and population size makes it a very strong probability that they are Fea’s Petrels. Indeed, that would be the case even if the entire Desertas Petrel population was in the Cape Verdes at the time.

2. I think to speculate on what is the most likely taxon in British & Irish waters, you need to combine the following:-
(i) Population size – with populations of Fea’s (500 pairs), Desertas (160-180 pairs) & Zino’s (65-80 pairs), this would indicate Fea’s Petrel on size of population.
(ii) Distributions – however, Fea’s Petrel (4,000km) would need to travel twice as far as Desertas or Zino’s Petrels (2,000km) so that would suggest Desertas or Zino’s Petrel on distance travelled.
(iii) Known movements – this is where the data logger information which suggests that Fea’s do no travel much but Desertas & Zino’s do is interesting. However, as only one Fea’s Petrel chick was recaptured as an adult and the proportion of the population sampled was the smallest, surely that is of limited use? The fact that Desertas & Zino’s travel to the south Atlantic, eastern seaboard, etc with such small populations, makes them thin spread doesn’t it? So I do not really buy the theory that this study suggests Desertas & Zino’s Petrel are more likely vagrants for us than Fea’s Petrel.
(iv) Plumage/morphology – as you point out, the size of the birds, their structure and the bill means almost all are Fea’s or Desertas Petrels. The fact that there few if any birds with massive bills suggests to me that they are not adult males certainly. I chatted to the late Jimmy Steele (whilst seawatching at Newbiggin) about the two I have seen well from boats in British & Irish waters. Both conformed totally to his British Birds article.
(v) Time of year – for me the August/September peak suggests that the majority of our birds are young Fea’s Petrels. As you say, non-breeding Desertas could be the source (or even extreme foraging trips), but I favour Fea's. I doubt that observer bias is that important. Sea temperature could also play a part in the August/September peak. Wouldn’t that mean birds wandering at that time of year may wander further into our waters?

3. Struggling to find my references this evening, but surely the significant differences in size and bill make sexing in the field possible (from boats) and surely as well bill sizes increase with age (whereas overall size of the bird is pretty much fixed on fledging). I was interested by the size variation of the bills of the Bulwer’s Petrels, I saw on Madeira and assumed that this was age-related if not also related to sex.

4. I don’t know If moult or plumage could ever be useful?

5. I know of one claim of Zino’s.

On balance, I think all three taxa could occur but personally, I think that we most likely get Fea’s Petrels……….

All the best
__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.

Last edited by Paul Chapman : Thursday 20th September 2018 at 21:19.
Paul Chapman is offline  
Reply With Quote
Old Thursday 20th September 2018, 22:01   #6
knotsbirder
Registered User

 
Join Date: Aug 2010
Location: Nottingham
Posts: 1,004
It was largely thought that the recent Irish bird was probably Desertas

Sam
__________________
These are my personal views and do not represent any organisation that I am associated with
knotsbirder is offline  
Reply With Quote
Old Thursday 20th September 2018, 22:24   #7
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
Quote:
Originally Posted by knotsbirder View Post
It was largely thought that the recent Irish bird was probably Desertas

Sam
Sam

I remember seeing some tweets referring to Desertas (or Fea's) - so shorthand for either/or. I don't recall it being 'uniquely brutish' as the Bob Flood article refers to some Desertas.

Any links?

All the best

Paul
Attached Files
File Type: pdf seabird-28-78.pdf (651.8 KB, 13 views)
__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.
Paul Chapman is offline  
Reply With Quote
Old Friday 21st September 2018, 11:06   #8
Paul Chapman
Registered User
 
Paul Chapman's Avatar

 
Join Date: Sep 2008
Location: Clevedon
Posts: 8,459
Sam

I think that this is the bird to which you are referring:-

http://www.irishbirding.com/birds/we...pe_Petrel.html

I am not getting 'uniquely brutish'. From memory, the closest to 'uniquely brutish' that I have seen is Scilly on 19 August 2014:-

https://www.birdguides.com/gallery/b...a-feae/576116/

All the best

Paul
__________________
Paul Chapman

I've decided to start a self-find list as self-help to reduce my level of self-harm.
Paul Chapman is offline  
Reply With Quote
Old Saturday 22nd September 2018, 09:29   #9
Muppit17
Registered User

 
Join Date: Apr 2017
Location: Hampshire
Posts: 97
Quote:
Originally Posted by Paul Chapman View Post

I am not getting 'uniquely brutish'. From memory, the closest to 'uniquely brutish' that I have seen is Scilly on 19 August 2014:-
I am getting the same 'feel' but this is meaningless as it is not a clear differentiator except for the largest of male desertas.

Not to quibble with your photographic skills but the photos of the birds Paul has posted cannot really show what is necessary. Looking at the underwing patterns there is a paper from Shirahai that shows wider variability than suggested and I read somewhere an article about the search for birds with all white underwings that have been seen - can't recall the reference at the moment. It is worth looking at the Madeiran Windbirds website for photos as the trip report pictures have improved massively over recent years. I dont know where to look for similar quality photos from Cape Verde.

It is also worth looking at Patteson's blog pages. They see "feas" off NC and their trip to Madeira made interesting reading - even if most of it was about their view of Band-rumped storm petrels. They spend so much time with the birds that their view point is most relevant.

The numbers game is also not necessarily relevant - it is arguable that if Fea's were present then 50 times as many Cape Verde Shearwaters should be seen in British waters.

The prevalence of suitable wind & currents could give a clue. Most of the birds are feeding either in the North Atlantic Conveyor (Gulf stream) or on the break between this and other ocean waters. Once on a favourable wind, 1000 km could represent less than a days travel and with minimal energy expenditure. It is known (believed) that there is interchange of feas/desertas between CV and Madeira so a skip into the stronger SW-NE system means the UK is not far for either species.

I believe to answer the questions - we need to understand more about the species habits and also try and understand if they are separable at sea. At the moment we dont appear to know enough to say if they are one species or another.
Muppit17 is offline  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Boyd's Sheawaters - Cape Verde (off Sao Nicolau) - April 2013 Paul Chapman UK Rarity Gallery 1 Wednesday 19th September 2018 21:25
Cape Verde - 8-15 April 2017 benmacdonald Companions for Birding Trips 2 Monday 20th March 2017 10:23
Boa Vista, Cape Verde April 2013 Jynx Vacational Trip Reports 4 Friday 17th May 2013 16:47
Boa Vista, Cape Verde April 2013 Jynx Cape Verde 0 Wednesday 15th May 2013 16:58
Fea's or Cape Verde Petrel jthoppes Opus Discussion Area 6 Saturday 8th September 2007 23:51



Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.15213704 seconds with 24 queries
All times are GMT. The time now is 09:09.