Monday 28 July 2014

Sooty Shearwater - some questions about moult

I've been working on some preliminary drawings for a plate of Sooty and Short-tailed Shearwaters for The Tubenose Handbook (Shirihai & Bretagnolle in prep). Looking through my photos of Sooties from California I was reminded of a mental note I made at the time but, as usual, forgot about until now. By a happy coincidence it's now approaching peak Sooty season so perhaps it's timely to chuck this particular pebble in the pond and see what happens.

Sooty Shearwater - 5/9/2011 off Point Loma, California
A fairly ordinary Sooty, the flight feathers look fresh - it's hard to tell from this angle - but the body feathers appear to be more worn/faded.

Sooty Shearwater - 6/9/2011 Channel Islands, California

Sooty Shearwater - 6/9/2011 Channel Islands, California
This one has almost completed primary moult - P10 is still growing - but everything else looks worn and the underparts are particularly pale and faded. Of the several hundred Sooties I saw this one was not unusual and in fact many looked even tattier, I just didn't get useful photos.

For comparison, here's a Sooty I photographed off West Cornwall a couple of months earlier.

Sooty Shearwater - 25/7/2011 Cornwall

Sooty Shearwater - 25/7/2011 Cornwall
This is typical of the birds I've seen off Britain over the years, uniformly dark, greyish or brownish depending on the light and in fairly fresh plumage; I can't recall ever seeing a Sooty as pale and faded as the ones off California. Admittedly most Sooties are seen at distance and often in poor light, not close and from a boat like this.

Some background: Sooties are, of course, southern hemisphere breeders, mostly SE Australia, New Zealand and Chile with much smaller numbers in the South Atlantic (Marchant & Higgins 1990). Adults and just fledged young disperse in late April to early May and most follow a figure of eight migration route into both the North Pacific and North Atlantic, returning south during August to October. Breeding adults begin wing moult immediately after the young have fledged (body moult begins earlier) and typically complete by September. Juveniles do not start moult until January or February of their second calendar year, throughout subsequent years this begins later and later until the typical breeding adult moult cycle is reached (Marchant & Higgins 1990, Howell 2012).

So birds not in wing moult during the northern summer (May to August) would be expected to be birds of the year. By September, moderately worn juveniles should differ from freshly moulted adults.

Where does this leave the very worn September birds? In these birds primary moult is nearly complete but secondary and body moult appears to have hardly begun. The moult cycle is behind, not ahead of, breeding birds so I presume these are not immatures. Are they sick or just not in breeding condition so delaying moult?

Curiously, most Sooties seen in summer in the western North Atlantic appear to be in fresh plumage, 99% of birds seen off North Carolina in late May and June are not in moult (Howell, 2012) so presumably are juveniles or recently completed second year birds. I get the impression, from personal observation and from published photos, that most birds seen off the UK are not in moult either although, since the peak time is August-September (Cramp & Simmons 1977), this may include some completed adults and immatures.

As ever, I started looking in the books and then had to chase up some references, which led to more references and so on. Here's a summary of some of studies to date on Sooty Shearwater moult: of 603 birds recorded in the North Atlantic between May and November by Brown (1988), none were in primary moult. However, Keijl (2011) found 35 of 76 (46%) of birds photographed near Rockall in July to be in primary moult. Cooper et al (1991) recorded moult in 653 beached Sooties from the southwestern Cape, South Africa; numbers (and percentage in moult) peaked strongly in February and March, the timing indicating these were either juveniles, young pre-breeders or failed breeders. Few were found during May to December as would be expected if most birds were in the northern hemisphere.

This post has turned into rather more than I intended (and apologies for getting a little bogged down in references to moult studies) but has only reinforced my impression that there's something puzzling going on. Are most North Atlantic birds juveniles or immatures as suggested by Brown (1988)? Do South Atlantic adults tend to travel north in the Pacific rather than the Atlantic as might be expected? Are juveniles more likely to be seen close to shore, do older and/or moulting birds feed in different areas? As ever, more research needed...

Sooty Shearwaters


Brown, R. G. B. 1988. The wing-moult of Fulmars and shearwaters (Procellariidae) in Canadian waters. Canadian Field Naturalist. 102:203-208
Cooper, J., Underhill, L.G. & Avery, G. 1991. Primary molt and transequatorial migration of the Sooty Shearwater. Condor 93: 724-730
Cramp, S., & Simmons, K.E.L. (eds.)1977. Handbook of the Birds of Europe, the Middle-east, and North Africa. Vol. 1. Oxford University Press
Howell, S.N.G. 2012. Petrels, Albatrosses & Storm-petrels of North America. Princeton University Press
Keijl, G.O. Sooty Shearwaters Puffinus griseus in the North Atlantic - moult studies using digital cameras. Marine Ornithology 39: 141-142
Marchant, S., & Higgins, P.J. (eds.) 1990. Handbook of Australian, New Zealand, and Antarctic Birds, Vol.1. Oxford University Press

Tuesday 22 July 2014

Ross's Gull close up at the Recreation Ground

21st July 2014 - Topsham


After two months of regular appearances at Bowling Green Marsh and Goosemoor and with just two brief visits to the Rec - when I wasn't there,  I finally get to add Ross's Gull to my local patch list. Better still, it fed on the near shore and the rising tide brought it to within twenty feet or so - by a long way much the closest I've yet been to it and well worth the wait.

All photos enlarge when clicked.

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham

Ross's Gull - 21/7/2014 Topsham
It's still a fairly shabby looking bird, head feathers dropping off almost as I watched and scapulars very worn. Primary moult about halfway through - P1-4 new, P5 growing (just visible on right wing) and P6-10 brown and very worn. No sign of replacement in the secondaries or coverts yet and the tail feathers are all old.

Just got to hope it hangs around another couple of months to show a nice fresh winter plumage.

Saturday 19 July 2014

First of the season

17th July 2014 - Topsham

Small numbers of juvenile Herring and Lesser Black-backed Gulls have been regular at the Rec over the last week or so and among this year's debutantes I recently found this striking bird.

Yellow-legged Gull juv 17/7/2014 - Topsham

Yellow-legged Gull juv 17/7/2014 - Topsham
Obviously my first thought was Yellow-legged Gull, it was very different to the Herring and Lesser Black-backed juvs nearby with its whitish head and body and those whitish fringes to the scapulars and coverts. The tertials and greater coverts looked fine and it did seem to be more advanced than other juveniles, the fringes to the mantle and upper scapulars (and a few of the lowers) were quite worn, all indicating the earlier fledging michahellis. Then I looked at it some more and, as usual, tried to talk myself out of it. The bill was not large and sometimes looked rather weak and graellsii-like. The flanks were quite heavily-marked and the legs very dark on the shins - mud perhaps?

Yellow-legged Gull juv 17/7/2014 - Topsham

Yellow-legged Gull juv 17/7/2014 - Topsham

Yellow-legged Gull juv 17/7/2014 - Topsham

Yellow-legged Gull juv 17/7/2014 - Topsham
It took flight eventually revealing, as I expected, dark inner primaries - though slightly paler than the outers - and a largely white rump and upper tail coverts contrasting with a black tail band. The tail band is somewhat broader than is typical of michahellis but, as far as can be seen from this distance and angle, the outer tail feathers seem quite white at the base.

Maybe not a classic michahellis but the only other option is a very pale Lesser Black-backed, or am I being over cautious? All comments welcome as usual.

Tuesday 15 July 2014

Dune Robberflies

12th July 2014 - Merthyr Mawr, Glamorgan

A weekend visit South Wales meant a few hours available to spend searching the dunes at Merthyr Mawr for some charismatic microfauna. I was hoping for Dune Tiger Beetle Cicindela maritima but drew a blank, fortunately Dune Robberflies Philonicus albiceps were everywhere I looked and provided a nice exercise for my rusty macro technique.

All photos taken with 180mm macro lens, f/8 at 1/160 -1/500 sec hand held. Species checked using the keys Stubbs and Drake (2001). 

Philonicus albiceps 12/7/2014 Merthyr Mawr
  P.albiceps is found on sand dunes all round the coasts of England and Wales, it is often common and can be abundant. Adults are found from mid May until mid October with numbers peaking in June and July (Stubbs and Drake, 2001). The larger robberflies (family Asilidae) are usually fairly obvious as such, with eyes separated by a 'dip' ('vertex' to be technical), bristly moustache and stout stabbing mouth-parts. They're all active hunters of insects and this one specialises in catching other flies as shown by this female below (prey species unknown).

Philonicus albiceps 12/7/2014 Merthyr Mawr
 P.albiceps is more than capable of tackling larger flies such this Empid (probably Empis tesselata) below.

Philonicus albiceps 12/7/2014 Merthyr Mawr
 The bigger the prey, the bigger the meal; I found a male (the shape of the tip of the abdomen is the clue in this family) sat on a rusty oil drum sucking the juices out of this Muscid (a Coenosia sp.?).

Philonicus albiceps 12/7/2014 Merthyr Mawr
 The proboscis is clearly visible piercing the prey's thorax; and while the mouth-parts are strong enough to hold the prey without using the legs, It helps that robberflies inject a venom that seems to kill their prey immediately.

Philonicus albiceps 12/7/2014 Merthyr Mawr


Stubbs, A.; Drake, M. (2001) British Soldierflies and their allies. BENHS

Monday 7 July 2014

Horseflies - my insect nemesis

I've never been a fan of horror films but I think I can understand the attraction; I get what I guess is a similar tingle of fear whenever I see a horsefly close up. I'm one of those who react badly to horsefly bites, typically it swells up like an egg and I suffer several days of intolerable itching (as I write I've got an unsightly red 'wound' on my arm after a bite six days ago). I have to admit though that they do have a kind of macabre beauty, I mean, just look at the eyes on this one.

A deer fly Chrysops viduatus 21/7/2005 Topsham
As in many families of flies, the sex can be told from the eyes - meeting on top of the head = male, separated (as here) = female. It pays to know this since only females bite (males prefer nectar) and the offensive hardware, the proboscis, is clearly visible under those green and purple eyes.

A word on Common/English names: given their predatory habits, biting flies tend to get noticed and a few of these have acquired common names. Since folk taxonomy rarely discriminates beyond the genus specific names have been invented in an attempt to make them 'more accessible'. In my opinion if you're interested enough to specifically identify this 'Square-spot Deerfly', you aren't going to be put off by it's scientific name - Chrysops viduatus Tabanidae.

This is one of about 30 spp. of horsefly (Tabanidae) found in Britain and this family contains the worst biters in my opinion - apart from mozzies of course, but that's an entirely different subject. They're often big, they're ugly (or are they beautiful, I can't decide) and their bites can itch like hell - I'd rather be stung by a wasp than bitten by a cleg (see below).  Deerflies may prefer deer but I've been bitten a few times - they usually go for the head and neck. Unlike these next two which tend to go for the arms or the back of the legs.

A cleg Haematopota pluvialis 9/7/2006 Topsham
Eyes not meeting on top so a biting female - be afraid.

A cleg Haematopota crassicornis 22/7/2009 Dunsdon
Eyes meeting on top so a non-biting male - relax, it's harmless.

Haematopota spp. (literally 'blood drinker') also go by the name of 'cleg' (always enjoyed the name - seems so apt for these quite unpleasant little beasts - and I make no political comment here). These are tough critters and can survive a fairly hard swat with the hand, after a few seconds they just pick themselves up and fly off - or more likely come back for another go at the back of your knee.

Clegs and deerflies are fairly modest sized flies - about the same as a housefly - but there are some alarmingly larger species out there. The larger 'horseflies' proper are nowadays divided between two genera, Tabanus and Hybomitra; There are about 17 spp. but many are rare and only half of them bite - the females, that is. Tabanus bromius (below) is actually one of the smaller examples but still about wasp-sized.

Tabanus bromius 27/6/2009 Salcombe Regis
 Eyes not meeting - a biting female - run away.

Next is a fairly large one, T.autumnalis. You'll notice I say 'fairly large', there are 'giant' horseflies out there - T.sudeticus should occur around these parts (though I've never noticed it) and can be an inch long, or about the size of a Small Elephant Hawk-moth!

Tabanus autumnalis 13/7/2005 Topsham
Eyes not meeting - a biting female.

The very similar genus Hybomitra differs most obviously in their hairy eyes - though you have to get uncomfortably close to see this. Here's H.distinguendua, a fairly large species.

Hybomitra distinguenda 22/7/2005 Topsham
Eyes separated - I think you know what that means.

I've never knowingly been bitten by one of these larger flies and I think I'd have noticed, in fact I'd probably need hospital treatment. I suspect they prefer to bite cattle or horses, humans just aren't worth the effort.

All species photographed and identified by me (in some cases verified by the good folks at using the keys in the excellent Stubbs and Drake (2001).


Stubbs, A.; Drake, M. (2001) British Soldierflies and their allies. BENHS

Thursday 3 July 2014

Blue-tailed Damselfly - a new one for the garden

3rd July 2014 - Topsham

Found this is the front garden this afternoon - I was actually listening for Wood-crickets (more later) - I popped back in for my camera and macro lens, eventually refound it and took some photos; no time to set up tripod, hand held 1/160 to 1/250 sec at f/8. It's always a job to get all the thing in focus at such close range, so quite pleased with result.

Blue-tailed Damselfly Ischnura elegans 3/7/2014 Topsham

Blue-tailed Damselfly Ischnura elegans 3/7/2014 Topsham
 This is a common species and I've photographed it a few times in the area, surprisingly never recorded it in the garden before. Females (like this one) come in several varieties, this rather nice specimen is the form 'rufescens'.

Wednesday 2 July 2014

Southbound - Common Sandpiper

2nd July 2014 - Topsham

Most people think autumn starts in September but for birds - and birders - the signal is the first returning waders, often as early as late June. By July things are really kicking off; this morning Common Sandpipers were in evidence at the Rec, at least three and perhaps as many as five.

Common Sandpiper - 2/7/2014 Topsham

Common Sandpiper - 2/7/2014 Topsham

Common Sandpiper - 2/7/2014 Topsham