Saturday, 30 September 2017

Aggressive stints

A couple of weeks ago at high tide I noticed a party of Red-necked Stints feeding around a small pond just above the beach. One bird was behaving in a very aggressive manor, running at all the other birds with its tail held vertically, bill downward and wings slightly opened while calling loudly. This in itself wasn't so odd but after a few minutes most of the other stints began to adopt the same behaviour until there was very little feeding taking place at all. This wasn't the first time I've noticed this aggressive behaviour and it seems to be a response to insufficient 'personal space' at or around high tide. What I don't remember having seen before is the same behaviour when space is restricted on a muddy field or other similarly cramped inland area.

The following few shots were taken last weekend just as the tide began to drop and the first few exposed square metres attracted the stints. Nothing else arrived until the water dropped further, the stints always seem more impatient to get on with things!

A juvenile Red-necked getting ready to take on all comers.

This adult scores more highly for technical ability and artistic interpretation.

The posturing never has the slightest effect (why bother?) and is followed by the charge.

Later in the day with the mudflats exposed all was sweetness and light... almost.

They would never have co-existed like this earlier in the day. Just having the space available seems to do the trick as they roved this way and that. No need to get excited, the big bird facing away is a Dunlin.

The Little Stint (right) stuck like glue to that small penalty spot-sized puddle. When a Peregrine flushed everything off, it came back to its private pool. The Red-necked Stints, now amicably moving across the mud, little realise they are about to transgress.  

Any Red-necked that crossed the invisible line would cause the tail-up threat posture.

The Little was kept pretty busy.

I never saw the same posturing from the lone Temminck's Stint, it would only voice a warning.

Thursday, 28 September 2017

Those alba Great White Egrets again!

I feel I keep banging on about how the status of Great White Egrets seems to have changed in Japan. I'm suddenly seeing so many alba, where are they coming from and why? If this increase is real rather than just being my impression then presumably something at their continental point of origin is driving the dramatic uptick in numbers I'm getting.

It wasn't until early 2012 I saw an alba in Kansai, an alba and modesta side by side; they looked so different! I'd had an eye out for them for years and thought I was probably overlooking very similar taxa but after that I was sure I couldn't have been overlooking them, at least not totally. I didn't see any the following winter then found three in the 2013-14 winter, one of these was in Shikoku where a local birder told me it had been a good winter for them there. There were no more blank winters but numbers remained low. I saw my first summer bird in June of last year then in the winter 2016-17 they seemed to be popping up all over the place. Nevertheless a flock of about 40 in Mie came as a shock. It probably came as a shock to the lone modesta on the lagoon to find so many 'monsters' that were oblivious to its best efforts to drive them off.

Last week I saw my first here since spring, again in Mie, and it stood out like a sore thumb as they always do. As there were four modesta on the same tidal inlet and I was able to get a few good comparative shots.

A sore-thumb alba, it isn't necessary to have direct comparison to see how much more massive they are.

One of  the four modesta sharing the tidal inlet.

These three images give a good indication of just how much bigger and bulkier alba is.

When it comes to seeing who's boss there's just no contest...

Check out the thickness of the tarsus and tibia, the size of the feet, the thickness of the toes... these birds are chalk and cheese.

A couple of old images showing the respective appearance in (presumed) breeding condition.

May 5th modesta with rosy-pink tibia and (mainly) black tarsus, green lores and black bill. This looks the deepest bareparts flush of the courtship period.

May 26 alba with legs fully flushed pink, tibia and tarsus, pale green lores and yellow bill. The intensely pink legs suggest this bird is in breeding condition yet that the bill hasn't begun to turn seems very odd unless this population doesn't become black in breeding condition. Perhaps this is an exceptional individual and perhaps age could play a part. The several early May birds I've seen on Mishima have a very dull (not blackish) tarsus and the bill varies from bright yellow with just a darker tip to the upper mandible (not unlike modesta later in summer as the black of breeding condition disappears) to what I'd describe as a golden-brown at any distance, as if a first coat of dark paint was failing to mask the yellow beneath. 

Monday, 25 September 2017

Volcano Island boobies... and the one that got away

Boobies attach themselves to any ship, with all the flying fish zipping out from the bow wake the chance of a relatively easy meal is way to good to pass up. In doing so they inadvertently provide a spectacular and photogenic escort through their oceanic territory. It was noticeable that when, after many miles, the Volcano Is Brown and Red-footed Boobies left us there was a brief period the fish could fly in safety before the more northerly Ogasawara Brown Boobies joined us. This was repeated further north the following day when there was another stretch of booby-free ocean after the Ogasawara escort peeled off and before the Izu Is birds came along side.

Brown Booby is a widespread species throughout the warmer waters of Japan and can even be seen in Kyushu coastal waters in winter... in harbours if you're lucky. Masked and Red-footed, unless storm-blown, require visits to more remote island groups. Red-footed is a common breeder in the Volcano Islands and Masked in the Yaeyama Islands.

Now you could say, 'when you've seen one Brown Booby you've seen them all'. You could; but it turns out you'd be wise not to, as I was to find out. Apart from females being significantly larger than males the sexes look alike, nor is there any readily apparent individual variation. On this trip I was interested in getting some shots of immature Brown Booby partly because I've seen very few and there seems very little variation in appearance compared to the immature Northern Gannets I used to see in the UK, with their gradual progression to adult plumage. Also partly because I remember in my teens the late Richard Richardson chasing me up for notes on an 'immature Gannet' we'd seen a few months earlier, Richard had a nagging doubt that it might have been an immature booby.

In that light it's all the more galling that the potential bird of the trip, a Brewster's Brown Booby Sula leucogaster brewsteri, was one that got away. It simply wasn't on my radar. According to the notoriously out-of-date OSJ list there's only been one Japanese record, however with a growing number of records in Hawaii, including breeding, this has to be a taxon to look out for in the Volcano Islands. The amazing occurrence of Nazca Boobies in Hawaii would also make any Masked Booby (which I've yet to see in the Volcano Is) worth more than the passing glance I allowed this bird.

I saw it approaching from the rear at about eye level, as boobies so often do, while we were slowly circumnavigating the southern island of the group. It was strikingly white about the forehead and fore-crown and the bill looked more reflective and colourless unlike the usual bright yellow. In fact it actually suggested an approaching Brown Noddy but as it was plainly a booby I lost interest before I'd had time to actually process what I was looking at. At that moment there was so much activity with Red-tailed Tropicbirds, White Terns, Brown Noddies and the potential for who knows what that the ship's daily escort simply wasn't a priority and I didn't even attempt to get any shots of it. It was only later as normalcy returned that the idea of a white-headed Brown Booby caused the cogs to slowly creak into action. The pain of this particular loss may diminish with passing time but at present the opposite seems to be the case.

Anyway... few images of the ones that didn't get away.

Juvenile Brown Booby

An April immature Brown Booby from the Yaeyama Is. I expect with the similar latitude the breeding timing will also be similar and this appearance with moult in the remiges and body fits a 2CY.

Juvenile Red-footed Booby

The same bird as above, the upperparts look strikingly grey at a distance.

Red-footed Booby in early November. So how old is this one? The potential for a very protracted breeding season could mean this is also a 1CY but perhaps 2CY seems more likely. If so then Red-footed must show a greater plumage variation between Juvenile and adult compared to Brown. 

Flight feather moult apparent here; I can only see nine primaries and the outermost is half grown. This must make it a 2CY.

The same bird as above; upperparts for comparison with next bird.

Compared to the previous bird this has slightly more white on the upperparts and white-spotted outer wing coverts. There doesn't seem a vast difference between this and the previous bird but this is a July bird, a full eight months later... or four months earlier. 

Same bird as above.

A far more advanced immature this month, just north of Ogasawara.

The same bird as above.

July immature with stepped wing moult, much brown in tail but breeding adult facial pattern.

Same bird as above. Two moult loci in both primaries and secondaries.

Adult Brown Booby

Male Brown Booby

Female Brown Booby

Adult Red-footed Booby September, facial area without intense breeding colouration.

July adult red-footed Booby with more intense facial colouration.

April Masked Booby

Even though I was really hoping to find rare seabirds on the trip, it was really difficult not to be distracted by the boobies putting on a great show alongside the ship. Particularly where the less often seen Red-footed was concerned.

The plunge...

The pursuit...