West Lyme Bay large shearwaters 2017

I've always found it interesting looking at the relative ratio of the two large shearwaters occurring in west Lyme Bay (or Devon). For some reason this far up the English (western) Channel, Greats usually outnumber Cory's, in terms of both numbers and number of records. So I thought as 2017 is looking like a good year for us (we can never can compete with Cornwall or W & SW Ireland!), I'd keep a tally for the ratios I have seen for west Lyme Bay this year.


Cory' Shearwater
Great Shearwater
21/07/17
181
82
22/07/17
2
3
26/07/17
1
2
28/07/17
0
17
02/08/17
0
3
03/08/17
1
3
07/08/17
1
1
11/08/17
0
12
Total
186
123
Records
5
8
 
So far its unusual in that Cory's have outnumbered Great. But that's really just down to one big Cory's day (21/07/17). So looking at the ratio of records, I've recorded Greats on eight days and Cory's on five so far. So still a better chance of seeing Great despite the difference in numbers. Hoping this good summer / autumn continues and I will revisit and add to the table and this post.

Out of interest both large shearwaters are listed a 'A' species by Devon Birds Records Committee, hence requiring a description from observers for all birds seen. It might be time to at least move them to a 'B', requiring brief notes if requested. Neither is really a rare bird in a Devon context. Perhaps what constitutes an 'A' and 'B' should be assessed using a statistical assessment inline with BBRCs approach. Yes, they are possible to miss-identify - there's a tendency to turn distant Greats into Cory's and we shouldn't be worried about using large shearwater sp., but with experience quite distant birds can be identified correctly. Recommended reading is Mike Langman's excellent guide to: Large Shearwaters at distance. Devon Birds 65(2): 32–37.

Of course views off headlands are never as good as from a boat!
Great Shearwater - West Lyme Bay
Great Shearwater - West Lyme Bay
Cory's Shearwater
Cory's Shearwater
But sometimes they're not too bad from a South Devon headland
Great Shearwater (underside) Berry Head
Great Shearwater (upperside) Berry Head
Cory's Shearwater (underside) Berry Head
Cory's Shearwater (upperside) Berry Head





6 comments:

  1. It's the Bird Fair next weekend - so usually guarantee a good seawatch while I'm away. Wednesday was looking good for Berry Head but I see the forecast has changed again now - not so good! Nice post Mark and a very good point about Cory's Shearwaters the chances of seeing one in Devon over Great is much lower. I think we worked it out a few years ago as having 8 Great Shear days to 1 Cory's Day but as you point out when Cory's to turn up they are often in good numbers, that gives any seawatcher the impression that Cory's are just as likely on a Devon seawatch.. that's far from the truth.

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    1. Cheers Mike, I think you'll be safe at the Bird Fair this year. Might be OK for Cornwall late in the week and I might stray off patch. But at last hopefully out on a shark fishing charter on Tues off Devon (I'm not fishing)- it might just be too windy though forecast looks ideal to me with a light/moderate westerly.

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  2. Another superb & interesting read& also some fine photographs. I would be very happy to see either of the large shearwaters but sadly the weather does not look ideal over the coming week but i will still (hopefully) enjoy some fine Balearics.

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    1. Thanks John, you might be OK later in the week, perhaps Cornwall or Prawle even.

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  3. well done on your Wilson's, think the weather looks ok for Berry Head tomorrow afternoon/evening?

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