When is a Bonxie not a Bonxie?

Skua headache...

It has been a manic few days, and my head is frazzled. Largely due to research into skuas, formerly of the catharacta variety. Firstly, it was (and still is) the task of trying to work out how many individuals were involved through photos taken and then secondly, the major task of trying to age these birds.

To put it simply, last week on Graciosa during the pelagic trips, at least three (possibly more?) of these bully boys were seen hassling the local gull and tern populations. And what I've worked out so far is: -
- juveniles (2nd calendar years) and adults are potentially do-able on moult (at least assignable to 'southern skua sp.')
- 3rd calendar year birds are not understood fully in terms of moult strategy, so are not do-able

Think about the decent nick of Bonxies on Shetland right at this moment in time - they are breeding birds in decent primary/secondary plumage. Adult 'southern skuas' breed later (in our autumn/early winter) so are now pretty screwed and in active wing moult.

A young Bonxie born in 2010 will have an earlier birthday than its 'southern skua' counterpart, probably by 4-5 months. So our northern hemisphere babies will be in a stage of moult, perhaps having even replaced all of their juvenile primaries and secondaries. Our fresh-faced southern boys/girls will be much fresher, and should still have retained juvenile feathers or at worst, be just started to moult. So here are a couple of birds to get us started.

Bird 1

This bird is presumably a juvenile that has gone through one wing moult cycle. P10 is a retained (presumably first generation?) feather while P1-P9 are newly moulted. Being so advanced in its moult cycle presumably means this is a Great Skua, as post-juvenile flight feather moult starts in March-April (as the body moult is completed) and is completed in June-late August, taking 150-180 days’. This advanced moult sequence, presuming it is indeed a juvenile, would rule out the southern hemisphere Skuas as they would not be as advanced as this bird (they would have been born later). The rather plain, concolourous upperwing-coverts also suggest a 2^nd calendar year bird.

Bird 2

Presumably not a 2^nd calendar year bird based on the state of plumage – two generations of ‘blotching’ in the upperwing-coverts, scapulars and mantle heavily ‘blotched’ – and bill all dark, as well as heckling on the nape (per http://www.surfbirds.com/mb/Features/skua-identification.html). In active wing moult – P8-10 retained (P6-P7) re-growing. The bird did not appear capped in appearance, once again suggesting a bird older than its 2^nd calendar year – post juvenile moult strategies are not fully understood in both southern and northern Skuas, so here perhaps here lies the issue? If this bird is an adult, Falkland and lonnbergi Brown Skuas commence moult in February to April, completing in June-August per Malling Olsen & Larsson 1997. Also note the colouration of the two newly moulted central tail feathers.

Here's a similar take on this tricky situation http://peteralfreybirdingnotebook.blogspot.com/2011/06/large-skuas-off-graciosa.html by Peter Alfrey and some more shots at by Gareth Knass athttp://www.flickr.com/photos/34986481@N07/sets/72157626907155648/.

The dangers of chumming

Monteiro's Storm-petrel

For sure, we all want to see birds well. And on Graciosa, Azores, I was treated to the best views you could imagine of both Monteiro's Storm-petrels and Wilson's Storm-petrels. Note the freshness of the primaries and secondaries on this bird (the warm season breeder) - although it's not got the best of forked tails for a Monteiro's Storm-petrel, you can rule out adult Grant's Storm-petrel (the cold season breeder) as they will be in heavy wing moult. Can you safely rule out a juvenile Grant's Storm-petrel though?

However, to get these views of petrels was not without sacrifice... as I write this, the clothes that I'm wearing are currently on their second (long) wash at 50 degrees. We had to prepare all the chum (including 45kg of rotten fish) ourselves, and my role for the week became the chum-master general while out at sea.

Note my binoculars precariously placed

Yep, they ended up in the chum after a few bouncy waves. A world first?

Temporary home for my binoculars

Flying without wings

This will be the first of several posts based on the excellent pelagics off Graciosa, Azores, this week. Wilson's Petrels are obviously a southern oceans breeding species, so it is no wonder given their breeding cycle to see birds in heavy wing moult. There were, of course, a couple of juvenile birds - really interesting to see how fresh they were in comparison to the adults (all photos here are of adults). There were a total of 12-15 Wilson's Petrels seen, all together feeding on our chum slick 18 miles southeast of Graciosa, in an area of shallow water (300 metres depth).

Back on land after a few days at sea...

Back on Terceira after a few days on Graciosa (where there was little internet access). Plenty more to come over the following days, but the shot above show one of the Western Palearctic's rarest birds - Monteiro's Petrel, or the 'warm season' Madeiran Petrel in the Azores. Other highlights have included some wing-moulting skuas, 12-15 Wilson's Petrels and a Rough-legged Buzzard/Hawk.

Back on the Azores

These days, away from Rotherhithe, the Azores seems to be my second home. And in particular, the island of Terceira. So once again, I was back there for the day in preparation for the ferry to Graciosa (where we'll be doing some pelagics this week). Highlights have included visiting some old faithfuls - the White-winged Black Tern (now a third calendar year) looks fully kitted out, a Pied-billed Grebe that got hooked during the winter has now seemingly fully recovered and acquired breeding plumage while a couple of Semipalmated Plovers were to be almost expected in the quarry at Cabo da Praia.

Killdeer breeding on the Azores again this year

Later today I'm off to the Azores, again. And it was the recent news of breeding Killdeer, where two young were observed on Santa Maria, that prompted me to post this. Though debatable whether or not the Azores really is 'this side of the Atlantic', a breeding record of any Nearctic wader there is still pretty incredible... and it's presumably the first definite American species of wader to have had successful breeding confirmed (this year and last).

You may ask 'what about those Pec Sands in Scotland'? They bred successfully but how certain can you be of their Nearctic or Siberian origin?

White-rumped Sandpipers displaying in Arctic Norway? No chicks. And those Spotted Sandpipers that attempted to breed on the Isle of Skye were apparently unsuccessful.

So there we go, Killdeer is the only definite yank wader to have bred in Europe.

Back on the patch...

It's been a slow time of late in Rotherhithe, briefly punctuated by this 1st-summer Yellow-legged Gull at Greenland Pier on Sunday. Not too regular this time of year in London, certainly not on the inner part of the Thames that I live on. Quite a smart bird to boot too.

The storm earlier this week unfortunately whacked out the Great-crested Grebe nest on the south side of Greenland Dock, though a check this evening of Inner London's only breeding Common Terns was more encouraging - the two pairs still on their islands on Surrey Water.