Saturday, 27 September 2014

Hybrid hirundine at Dungeness

It has been a long September since getting back from the Azores. Up until today, and despite a fair amount of effort, the best thing I'd seen was a Whinchat at Crossness a couple of weekends ago. And with the southeast London scene still feeling pretty stale, I headed off to Dungeness for the day - primarily to look at gulls.

However, while at the fishing boats (where there was a 1st-winter Little Gull, 2 Med Gulls (2nd & 1st-winters) and an Arctic Skua) news filtered through that Dave Walker had trapped a hybrid Swallow x House Martin at the observatory. I'd never seen a hybrid like this before, and particularly as it was being ringed nearby, headed over to have a look: -

hybrid Swallow x House Martin (juvenile) at Dungeness, Kent 27th September 2014. Note the intermediate features including more uniform forehead, irridescent mantle and rear crown, off white rump patch and undertail lacking any spots as in House Martin while peach undertail coverts and ghosting of throat patch and breast band all characters of Swallow.
Thanks to Dave W, Dungeness Bird Observatory and the local birders.

Sunday, 21 September 2014

A presumed South Polar Skua on the Azores August 2014

August 27th was already a good day - multiple sightings of a Swinhoe’s Storm-petrel out on the Bank of Fortune plus Bulwer’s Petrels, Monteiro’s Storm-petrels and Great Shearwaters galore. Mid afternoon, I was doing the chumming as usual when out the corner of my eye I spotted a bird coming in to investigate the boat. It was purposeful, robust – a catharacta skua (or what was formerly called a catharacta skua) – and as such I shouted to everyone to take a look. This was the first ever large skua (Great Skua/South Polar Skua) that we’ve recorded on August pelagics off the Azores, so inevitably I was a little excited. We’d seen Great Skuas in late May 2011, but with an increased understanding of South Polar Skua migration from waters in the northwest Atlantic southeastwards in early autumn, as well as recent extralimital records from Lanzarote and Madeira, this species was always going to be a possibility in Azorean waters in late August.
Fortunately, the bird came in a couple of times and it was evident in the field that we were dealing with a bird in wing moult, but in relatively dull conditions and with the bird above the boat, it was a case of take photos and look at the details from there. The identification consensus on the boat was split, with some people feeling that it felt lighter in build than your typical Great Skua while others were rather nonplussed. Nevertheless, once we got back to land and to the hotel, the first thing I did was whack an email off to one of the authors of the British Birds paper on the South Polar/Great Skua identification.
Having had the experience of the Great Skuas off Graciosa in May 2011, I knew the key to getting the identification right is getting the ageing correct. What you have to think about is when in the year birds in the southern hemisphere are born compared to Great Skuas – basically 6 months apart. Adults of both South Polar and Great Skuas have one wing moult each year, after the breeding seasons, while birds in their first 12 months have two wing moults.

Initially, ageing proved difficult and therefore has made the process more protracted. With Martin Gottschling being particularly proactive in his approach, this bird has been aged as in its 3rd calendar year or older on the basis of cold-toned, scalloped scapulars that lack any streaking or golden tones to be expected in a 2nd calendar year Great Skua in late August. Additionally primary moult would either fit a 2nd calendar year Great Skua or an older South Polar Skua – with P10 in pin (1), P9 half grown (3) and P1 to P8 fully grown (8 x 5) I’d be giving this bird a primary moult score of 44. For late August, this would indicate a South Polar Skua taking the moult score charts as red (despite a limited sample) and that the bird has been aged correctly.
The bill is also relatively long and parallel-sided (described as a meat cleaver by one of the authors of the paper!), and the underparts are smooth contrasting with a dark underwing. Although not obviously capped, there is a lack of neck speckling which again is a pro South Polar Skua feature. There has been talk of suspended moult in this bird (in relation to P1 and P2), but I have struggled to see this.

It’s also interesting to look at a confirmed South Polar Skua in the North Atlantic at a similar time of year and presumably of a similar age. A bird ringed in the South Shetland Islands in 2005 was remarkably seen in waters off Martha’s Vineyard, Massachusetts on 15th August 2007. Photos and details can be found here. The primary moult, body colouration and extent of white on the primary bases is near identical to this Azorean bird.

The process of identifying South Polar Skua is really tough, and despite what seems to clarify and categorise birds by primary moult scoring, this last few weeks has clearly shown me there is still a lot to be learnt. Identifying these birds is far from being a precise science, with a lot of subjectivity on plumage features let alone any consideration of hybrids from the southern skua complex (including South Polar and Brown Skuas). However, documenting birds such as this that seem to fit the bill based on current criteria and then reviewing them going forward on increased knowledge can only be of benefit to the whole identification process.

Many thanks to several people involved in this record, most notably Martin Gottschling who reinvigorated interest in this bird, as well as Dani Lopez Velasco, Dick Newell, Chris Batty and Peter Alfrey for providing decent discussion and airing their views. Also to everyone on the boat who experienced it in its true life glory.

Sunday, 14 September 2014

Monteiro's Storm-petrel photoshoot

A couple of weeks birding in London quickly brings you back down to earth after a session in the mid-Atlantic. Whinchat and Greenshank this weekend, Lesser Whitethroat and Whitethroat last weekend the only slight bits of interest. So, without any more ramblings, here are a selection of Monteiro's Storm-petrel photos from the seas and land off Graciosa.

Monteiro's Storm-petrels on Ilheu da Praia, August 2009. I was privileged to be able to spend a couple of nights in the colony on this uninhabited island, a great experience that is brought back to me every time I sail past it.
This cryptic species is the 'hot' season breeder on the Azores, with egg laying going on from May to early July - hatching spans from early June and the last chicks fledge by early October. This in itself provides a bit of a headache for those looking for 'cold' season [Grant's] Storm-petrels at sea on August and September pelagics, as young Monteiro's will have a full set of wings too.

Monteiro's Storm-petrels off Graciosa August 2014 (top three) and August 2013 (bottom two)
Here are a few fresh plumaged Monteiro's Storm-petrels from pelagics in late May/early June - it was only on the last day of these that we discovered the Bank of Fortune. This area, therefore, is relatively untouched in what I reckon will prove to be the best time for Black-capped Petrel in Azorean waters, plus other pterodromas...

Monteiro's Storm-petrel off Graciosa, May 2011. Note the fresh appearance of these birds at this time of year.
Monteiro's Storm-petrel is the guaranteed star of pelagic trips off Graciosa that I've been involved in during recent years, and up to 50 birds can usually be seen on a full day visit to the Bank of Fortune.
Monteiro's Storm-petrel chick, Ilheu da Praia August 2009
There are just a couple of places left on next year's trip (the last week of August 2015), so do contact me if you're interested.

Saturday, 6 September 2014

Azores August 2014 - update 3 - Cabo da Praia

It's now just under a week since I returned from the Azores and, as usual, I've been punished for having such a good summer with a typically manic first week back at school. On the positive side though, it's only 7 weeks before I'll be back in the middle of The Atlantic.

When I came off Graciosa last Friday, I purposefully staggered my journey back to London with a day on Terceira. I could have flown back direct on the Saturday morning from Sao Miguel, but wherever possible I like to visit the famous quarry at Cabo da Praia as there's often a turnover of birds. And compared to Monday's visit, there were three new adult White-rumped Sandpipers - one that had been found on Friday, and two fresh in while I was there.
Two White-rumped Sandpipers, Cabo da Praia 30th August 2014
Though the three most common waders at Cabo da Praia are Turnstone, Sanderling and Kentish Plover, there is usually a healthy mix of other species - this year it included two Curlew Sandpipers, a Knot, two Ruff, a Common Sandpiper, two Grey Plovers, up to ten Whimbrel (including two Hudsonian), a Little Stint, two Semipalmated Sandpipers, two Semipalmated Plovers, seven Black-tailed Godwits and of course the star of the show, a Short-billed Dowitcher that turned up in early September 2013. And in the week since I've left, a Spotted Sandpiper and a new Semipalmated Sandpiper have arrived...
Short-billed Dowitcher and White-rumped Sandpiper, Cabo da Praia 30th August 2014