Bulwer's Petrel - the same the World over?

I don't do much seawatching anymore, a few good boat trips spoiled it for me. A couple of years ago I spent a few days on, or rather a few miles off, Madeira getting to grips with some of the Western Palearctic's rarer and more local species. As I had hoped, Bulwer's Petrel Bulweria bulwerii were numerous and often close. They weren't too easy to photograph, they moved fast and the boat rolled on the swell, but at least they kept coming past and, by blasting off hundreds of shots, I got a few half decent images.

 

Tubenoses which breed in low to mid latitudes tend to be quite restricted in their breeding sites, Bulwer's isn't. Of the 'big five' Madeira tubenose specialities, two species, Zino's Petrel Pterodroma madeira and Desertas Petrel P.(feae) deserta, are extremely rare and breed only on one island each; while three, Bulwer's Petrel, White-faced Storm-petrel Pelagodroma marina and Madeiran (or Band-rumped) Storm-petrel Oceanodroma¹ castro, are both fairly numerous and are found in both the Atlantic and the Pacific.

Of course I know things are a little more complicated than that; Madeiran Storm-petrel in the strict sense only breeds in the Madeiran and Canarian archipelagos, the other taxa in the complex being variously regarded as subspecies or species.  White-faced Storm-petrel (with up to six subspecies) breeds on islands in the North and South Atlantic and also from southern Australia to the western Pacific.

Bulwer's Petrel is found breeding in tropical and sub-tropical zones across The World's oceans from the eastern Atlantic to the central and western Pacific and the western Indian Ocean (it may also breed in the South Atlantic on St. Helena). However, unlike the two Storm-petrels, there are no recognised subspecies. Bulwer's Petrels from Hawaii and the seas off Taiwan appear to be identical from those from Madeira and the Canaries - there appear to be no plumage or size differences that I can detect from specimens. Other than Jouanin's Petrel Bulweria fallax, which, when lumping was the fashion, was sometimes thought to be conspecific with Bulwer's (in fact it's much bigger and a different shape), I don't think Bulwer's has ever had any subspecies. The monotypic multi-ocean distribution of Bulwer's Petrel is, in fact, so unusual for a (sub)tropical tubenose that only Wedge-tailed Shearwater Puffinus² pacificus shows a similar pattern, although in this case it does not occur in the Atlantic.

I'm not aware of any research into the genetics of these populations though I suspect the results would be interesting.

Many thanks to Caterina Fagundes and Hugo Romano of Madeira Windbirds for some quite splendid boat trips, I can't recommend them too highly.

 ¹ It has been suggested that this species (species group) differs so much from 'typical' Oceanodroma that it may be better placed in it's own genus Thalobata.

 ² Like the other large shearwaters, probably better placed in a separate genus Ardenna.

Getting distracted again

13th-15th August - Topsham

The days are long and so are the gaps between posts. I could make excuses about pressures of work but the truth is I've been taking a bit of a break. There doesn't seem to be much happening bird-wise locally (maybe I'm not looking hard enough) so I find my attention wandering. As a five minute break from my desk, I like to take a walk down the garden with my macro lens/tripod set-up. There's nearly always something of interest. So, at the risk of disappointing those expecting photos of gulls, sketches of birds or even an update on my Tubenose work, here are some more insect photos. All taken in my back garden in the last few days - the technical details (if anyone's interested) are: Nikon D200, Sigma 180mm macro, Uniloc tripod and Manfrotto ball head, no flash, just long exposure, mirror lock-up, cable release and wait for the wind to drop.

First here's a bug, Deraeocoris ruber, family Miridae. I've photographed this species a few times and it varies a lot in colour; this is a paler individual, some are quite blackish - mostly males according to Southwood & Leston (1959). Both adults and young are predators of aphids and other small insects.

The next two shots show a Hoverfly, a Eumerus sp. There are four British species (Stubbs and Falk, 2002; Ball and Morris, 2013); it's not E.sabulonum as that has a reddish base to the abdomen, also I think E.ornatus can be ruled out as the ocellar triangle is not far forward enough. This leaves E.funeralis, which has a distinct bare patch on the underside of the hind femur, and E.strigatus, which doesn't. I suspect this is strigatus but can't be certain with these views.

Now for some flies with somewhat less savoury lifestyles, Tachinids, all identified, with varying degrees of confidence using Belshaw (1993) and Tschorsnig and Herting (1994). First we have Voria ruralis, I see this in some numbers locally in late summer - when I look. It parasitises moth larvae, mostly Plusiinae - Silver Y, Burnished Brass and Dark Spectacle are mentioned.

The next two photos show another fairly common Tachinid,  Eriothrix rufomaculata. The reddish patches on the sides of the abdomen (just visible through the wing) are typical, though not diagnostic, this was keyed using Belshaw (1993). This also appears to parasitise moth larvae, although it's usual host is surprisingly unknown given that it's so common.

This last fly is a new one for me, using Belshaw it keyed out as Gastrolepta anthracina, I checked reliably identified photos (e.g. Diptera.info) and, a little surprisingly, they seem to match. I'll put it down as a probable and check with those who know. This doesn't seem to be a common species - though it's hard to tell with such an under recorded group - and mainly found in coastal southern England; the host species appear to be beetles.

References

 

Belshaw, R. 1993. Tachinid flies. Diptera: Tachinidae. Handbooks for the identification of British Insects. Royal Entomological Society of London 10, Part 4a(i).
Southwood, T.R.E. & Leston, D. 1959, Land and Water Bugs of The British Isles. Warne, London.
Tschorsnig, H.P. and B. Herting. 1994. Die Raupenfliegen (Diptera: Tachinidae) Mitteleuropas: Bestimmungstabellen und Angaben zur Verbreitung und Ökologie der einzelnen Arten. Stutt. Beitr. Naturk. (A) 506, 170 pp.

Silver-washed and White

26th July 2013 - Upton Hellions, near Crediton

With just five days to go I've finished all my tetrads for the Devon Bird Atlas. It's been a lot of fun and I've seen parts of Devon I never knew existed. Mind you, I could do without the nonexistent footpaths, the over-friendly livestock and the blood-sucking flies. But it's been a great excuse to just go somewhere new and wander about - a hobby of mine, in fact. I've had to be fairly single-minded though, I'm too easily distracted by nice insects and I am supposed to be counting birds after all.

This morning, as a change from the usual lanes, fields and hedges, I found myself in a patch of woodland waiting by a gate while two tractors maneuvered past each other (and me), I noticed butterflies feeding on some sunlit brambles and decided I could spare a few minutes. Of course, I had my camera with me.

Two male Silver-washed Fritillaries, the second a little worn at the edges. There doesn't look to be much nectar left in those flowers but they chased off anything else that wanted a share, or maybe they were protecting their prime position in case a female came along.

White Admirals are butterflies I don't see often enough, I've certainly never had much success photographing them. The last shot didn't quite work out but it's the only one I got of the underwings, possibly even smarter than the upper side.

Juvenile michahellis finally arrives

23rd July 2013 - Exeter Quay

I was wondering when the first one would show up. In fact, I was starting to think that my rudimentary gull identification skills were leading me to miss them among the juvenile Herring and Lesser Black-backed Gulls. So, after weeks of fruitlessly staring into the afternoon sun at Topsham Recreation Ground, I take Carolyn's advice and hop on my bike for the short ride into Exeter - maybe she thinks I could do with the exercise? Within minutes of arriving at the Quay I've got one.

It's a nice big bird with a fairly hefty bill, neat and contrasting scapulars and coverts and classic thin white 'thumbnail' tips to the tertials. The belly is white and fairly unmarked and the outer greater coverts get darker at the base.

After being quite unpleasant towards the other gulls (another ID clue) it eventually flew. The wings shows dark inner primaries (and a good dark wedge on the outer greater coverts); the black tail band is broad in the centre and narrows outwards while the upper tail coverts and rump are bright white with only a few dark spots. The underwing is well marked but nowhere near as dark as a Lesser Black-backed.

Now I could do with a few more, or even a nice fresh, photographable Caspian Gull...

Mostly Juveniles

9th - 17th July 2013 - Topsham

There is, of course, a down side to the current bout of what I hear is called 'summer'. On the Exe at Topsham Recreation Ground gull numbers are highest during afternoon and evening low tides when they drop in to bathe, preen and rest. Right now this means looking west with bright sun behind the birds - deep shadows and blown out whites and generally pretty frustrating. Although I don't think I'm missing out on much, I can only assume that the really good birds - like a nice juv Caspian Gull? - are waiting for the bright overcast days when their photos will look much nicer.

Wader passage is slight, a single Green Sandpiper, a few Curlews and a handful of Common Sandpipers (one of 15 on the 17th shown above). More of interest to me right now are the juvenile gulls. The first to arrive were the Black-headed Gulls, showing a few variations on the basic pattern - dark scapulars with neat pale fringes, and a dusky head with a dark 'shawl' - most are fairly brown on the mantle but a few are almost black. The second bird appears to have already moulted a few smaller scapulars and median and lesser coverts.

Then the first of this year's Herring Gulls showed up, barely out of the nest and still growing their outer primaries. Mostly pretty straightforward with their sandy brown tones, well notched tertials and pale inner primaries.

And a few Lesser Black-backed for comparison. Generally darker and often much less brown than Herring (though the light can alter that dramatically). Classic thin tertial fringes and more solidly darker outer greater coverts easy to see on the first two, and the dark inner primaries is the clincher.

And maybe it's cheating but here's an ID feature not mentioned in the books - these youngsters are still at least partly dependent on their parents for dinner. Easy now, aren't they?

Surprising as it may seem, there are birds other than gulls, here's an egret with yellow legs. Could this really be mistaken for a Cattle Egret?

Meanwhile, I'm still waiting for one of these...

Yellow-legged Gulls - or just gulls with yellow legs?

24th-28th June 2013 - Topsham

 

Most of my birding currently seems to involve staring at gulls on the Exe at Topsham. June can be a desperate time for gull watching, the wintering birds have gone, spring migration is over and the fresh juveniles have yet to appear. Still, there's plenty of gulls to look through at least. The local Herring Gulls are all well into their complete moult, the first and second summer birds often looking shockingly worn with pointy brown primaries and whole rows of coverts dropped. There's some variety in that they can all look so different - and often nothing like those nice, neat field guide illustrations.  Mid Summer is also when Yellow-legged Gulls should start to show up. What I seem to be getting though is 'not quite michahellis' - birds that at first glance look OK but on closer inspection just look wrong. I've seen three different birds at Topsham Rec in the last week, all looked promising at first but ultimately failed to satisfy.

Here's the first - 24th June; darker mantle than Herring Gull, yellowish legs, a lot of black on the outer primaries with a small mirror on P9.

Here's number two - 26th June; as before, darker mantle than Herring Gull, yellowish legs, much black on the outer primaries with a small mirror on P9.

Now here's number three - 28th June; again a darker mantle than Herring Gull, yellowish legs, much black on outer primaries but with no mirror on P9.

All three birds stood out as clearly different from the nearby Herring Gulls, most obviously in their darker mantle, but also leg colour and primary pattern. So why aren't they Yellow-legged Gulls? Several things appear odd:

Mantle shade - darker than argenteus alongside, but probably not actually dark enough for typical michahellis; also #1 and #2 at times looked a little too blueish grey.

Leg and foot colour - certainly yellowish from some angles, though often, when viewed from behind, appeared quite pink. Typical June michahellis should have bright deep yellow legs and feet.

Primary pattern - The broken black band on P5 of #2 and #3 are, while not impossible in michahellis, are rare. Also the whitish 'moons' behind the black on P5-7 on all three are atypical of michahellis.

Orbital ring and gape - difficult to see clearly but don't appear to be dark, they both should be red in breeding michahellis.

Moult stage - #1 has not yet begun primary moult, #2 is growing right P2, left P3 and P2, #3 is growing P3 on both wings. The second and third are a little late for michahellis whereas #1 hasn't even begun primary moult.

Size and structure - compared to most nearby Herring Gulls, all three birds looked small, with unimpressive heads and bills. This is admittedly an area of much overlap and they could just be small females but their size and shape certainly doesn't favour michahellis.

Most of these features are possible in 'proper' michahellis - with the possible exception of the orbital ring and gape which is very hard to determine from these photos. But, taken as a whole, I'm forced to the conclusion that all three birds are probably hybrids of some sort. It's hard to say what the parents are - although Herring Gull is certainly involved - and, of course, they don't have to be first generation crosses.

I've now seen seven different apparent hybrids at this site in the last 8 months and, while one or two were clearly not yellow-legged, I wonder how many of the others I'd have called michahellis on a cursory glance? I notice that Yellow-legged Gull has now been 'downgraded' to a category B species by the Devon Rarities Committee, i.e. only brief notes required. I wonder if this is wise?

Postscript: at the same time as the second bird on the 26th June I got brief views of a better candidate michahellis - it dropped in briefly showing darker grey mantle and an apparently dark orbital, briefly head-scratched showing nice yellow feet before disappearing when I was distracted - so no flight shots. It's not an adult - the grey-tipped blackish primary coverts just showing combined with the white mirror on an old P10 indicate a 4th calendar year bird. There's a lot of black on the just moulted P5 - just beneath the tip of the longest tertial - and also some black on P4. I would have preferred a nice spread wing shot but I'm happy to call this a michahellis.

Finally, many thanks to my good friend Martin Elliott who, unlike me, really knows a lot about gulls, for his invaluable, patient and expert input with these birds.

Whinchat, Dartmoor

22nd June 2013 Challacombe Down, Dartmoor

 

Getting a little slack with 'regular' posts - truth is there's rather little about right now at my local haunts. Still waiting for the next 'interesting' gull at the Recreation Ground, even a Mediterranean or a Yellow-legged Gull would be something! If things don't pick up soon I may have to start moult scoring Herring Gulls...

Meanwhile I had a wet and windy afternoon on a beautiful part of Dartmoor on Saturday. Best birds were a pair of Whinchats on territory - sketches of the male and then the female.