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Thread: Prions - Wollongong Pelagic 24th July

  1. #1

    Prions - Wollongong Pelagic 24th July

    There was some discussion about prions on last weekend's pelagic trip off Wollongong, followed by many photos taken of Prions (but I managed only a handful). I thought I'd start the ball rolling and hopefully others will post some of their photos.

    After looking closely at the birds at sea and now at a computer I'm confident that a considerable proportion of prions seen were Antarctic Prions (a new bird for me, so I was a novice).

    Attached are two separate individuals that show the diagnostic characters well. Relative to Fairy Prion these are:
    Bill shape (elongated and slightly 'bowed')
    Less extent of black pigmentation on tail
    Greater extent of grey on sides of breast

    Something that I also noticed at sea was the difference in the contrast of the 'M' on the upperwing. In Antarctic Prions it was less distinct, as seen in the photos. While in Fairy the 'M' along with the long dark tail tip was conspicuous in flight. For me it helped pick them out from the crowd at sea and then focus in on looking at the other features more closely as they wizzed past. This difference is almost certainly due to timing of moult (and hence plumage wear) - see the bottom image showing the bird in primary moult. I wonder if this difference in timing may be a helpful ID clue during this time of year?

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    Last edited by DJPortelli; 27-07-2011 at 04:25 PM.

  2. #2
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    Thanks for posting these. I haven't had a look at my photos from the weekend yet, but there were certainly a lot of Antarctic Prion's around. Hopefully over the weekend I'll get to have a look at them.

    Did you (or anyone!!) photograph or see any Slender-billed Prion's on the trip? I heard people calling them, but couldn't identify any myself.

  3. #3
    I was looking quite closely at the prions, particularly those being called as slender-billed from those on the lower deck while I swayed constantly side to side on the upper deck. Hence the reference to "some discussion".

    I didn't see any birds that I thought may have been slender-billed, but Antarctics were new to me so prion scrutiny is not my forte. I hope that others will post some of their photos to this thread.

  4. #4
    I will have a better look at my pictures over the weekend. In my case, it was also the first time that I had a more decent look at Antarctic Prions, and at this stage I guess I am not confident that I have seen any Slender-billed Prions. I will try to upload some pics in a couple of days, but they look pretty similar to the pictures above, in general.

  5. #5
    Here is an attempt to upload a picture of what should be an Antarctic Prion:
    Attached Images Attached Images  

  6. #6
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    Here's a couple of mine from the weekend, both Antarctic's I think. All my photo's I believe are either Antarctic or Fairy's. I'm confident I didn't see any Slender-billed at all on the trip.

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  7. #7
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    I agree with everything above. I didn't see any Slender-billed Prions (well at least not amongst the birds that showed well or for long) and certainly didn't photograph any. It has been a great winter so far for east coast pelagics to get in some practice on non-Fairy Prions. We again had a few Slender-billed Prions off Eden on Sunday (31 July) but no Antarctics, so quite different to our previous weekend off Wollongong. I was also really interested in the Salvin's Prions off Southport and how they were positively identified (I don't have any experience of Salvin's Prions in the field so very keen to learn more). There seems to be a fair bit of misleading info re. their identification. From quick chats with a few people (rather than fully trusting the literature), it really does seem to come down to bill dimensions and the visible lamellae along the basal third of the closed bill (obviously difficult to see without the very best/sharpest close photographs - usually only possible in the hand). Obviously the general structure may be a good clue to begin with - one of the Southport birds is particularly bulky and big-headed/thick-necked looking.

    So I have a few questions for birders who are experienced in and confident of Antarctic v. Salvin's Prion identification?

    1. HANZAB and from discussions with other seabirders have favoured using the pink webbing of Salvin's Prions versus the grey/whitish/bluish webbing of Antarctic Prions. I really don't think I would put any confidence in this. I understand webbing colour can be consistently different (eg. yellow webbing on Wilson's Storm-petrel or black webbing on Black-bellied Storm-petrel) but pink webbing would surely be prone to fluctuations based on the blood being pumped to the feet or could fade on beach-washed birds. I think the vast majority of the prions seen off Wollongong on Sat 24th July had pink webbing (see attached photos) but were Antarctic Prions (or at least I thought were Antarctic Prions). Any comments?

    2. How consistently is the half-collar less pronounced on Salvin's Prions than on Antarctic Prions?

    3. Are there really any consistent/non-overlapping differences in the undertail pattern?

    4. Whilst chatting to Paul Walbridge today he suggested that maybe it was worth looking at the extent of the black skin around the gape. Any thoughts? Certainly the Southport birds have this exaggerated 'grin'.

    5. Moult - on one of the NZ websites sites it suggested the Antarctic Prions moult later than the others and that most of the Antarctic Prions they are picking up amongst the wrecked birds along their coastline are in heavy primary moult at the moment. Certainly a lot of the Wollongong birds were in the middle of their primary moult, whilst others had moulted half their coverts, whilst some of the 'Antarctic-type' Prions seemed to be in relatively fresh plumage. Comments?

    I have attached four shots that hopefully show some of the range in moult, one head on image of a bird's bill, and the obvious pink webbing.

    Cheers Dan

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  8. #8
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    Some links to prion bill comparisons:

    1. Great comparative shot of prion bills/heads from the recently wrecked birds along New Zealand’s coast. The bowed edge of the Salvin’s Prion bill compared to the much straighter edged bill of the Antarctic Prion is well illustrated.
    http://blog.tepapa.govt.nz/2011/07/1...ealand-shores/

    2. Salvin’s Prion in rehab – from this angle the bill base appears deep but not massively so.
    http://www.flickr.com/photos/angrysunbird/5941950009/#/

    3. Stunning in-the-hand shots of Salvin’s, Slender-billed and Broad-billed Prions.
    http://www.birdingnz.net/forum/viewtopic.php?f=9&t=1282

    4. Line drawings of Prion bills and photos of skulls. The bill on the Antarctic Prion skull actually looks (to me) to be midway between the Salvin’s and Antarctic Prion line drawing.
    http://www.shearwater.nl/?file=kop55.php

    Cheers Dan

  9. #9
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    I am posting these images on behalf of Paul Walbridge

    There are three images of Salvin's Prions and one of an Antarctic Prion seen off Southport (QLD) recently. The top image is the Antarctic Prion and the rest were identified as Salvin's Prions. The basal bill depth on the Salvin's Prion in flight is particularly impressive.

    Cheers Dan

    [Paul - maybe the reason these images would not load for you was because they were still longer than the max allowed length (1024pixels)]

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    Last edited by Dan Mantle; 02-08-2011 at 01:35 AM.

  10. #10
    Storm-Petrel
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    Might as well add a few Slender-billed Prion shots (like most of my photos they are pretty sub-standard but they get the message across) for comparison as there was certainly some confusion on the Wollongong 24th July trip. These shots are from Wollongong on the 16 July and Eden on the 31st July.

    Cheers Dan

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  11. #11
    Hi all,

    I cannot really add to the solution but certainly to the confusion!

    Here are some photos that Raja shot during the 2010 June 12 Sydney Pelagic (four folders). I believe that most of the "Antarctic Prions" are indeed Antarctic Prions. However, some could be Salvin's. I am not so sure about most of the Slender-billed Prions anymore: Some - I believe - are still Slender-billed, but others are more likely Antarctic.
    http://www.adarman.com/Pelagics/Sydn...10904834_H6Sdv
    http://www.adarman.com/Birds/Petrels...00550886_cTkLU
    http://www.adarman.com/Birds/Petrels...00605635_MQZsv
    http://www.adarman.com/Birds/Petrels...00609624_Gy4re

    For comparison also some shots of certain Slender-billed from the 2011 July 09 Sydney Pelagic.
    http://www.adarman.com/Pelagics/2011...196828_w3xFQWw

    Any thoughts?

    Cheers,

    Nikolas

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