This was unexpected

18 08 2013

“But, instead of what our imagination makes us suppose and which we worthless try to discover, life gives us something that we could hardly imagine.”

– Marcel Proust

One of the best things about birding is that every new day is different from the previous one, mainly because of the migration phenomenon but also because of our point of view, because a different state of mind leads to different approaches to a very similar reality. After a month ringing reed warblers (i.e. Reed, Marsh and Sedge warblers), I felt I needed a day at the Lighthouse. This day was finally last Friday, preceded by another night of wader ringing. The night started with a very nice dusk at Nabben but the ringing itself was not so successful this time in terms of numbers. However, an impressive adult (male) Oystercatcher delighted us with its elegance.

Lighthouse at dusk


Ringing at the Lighthouse was indeed very pleasant. 48 birds in total, with some nice species among such as Wood warbler and Red-backed shrike, hard to catch in our loved Flommen’ reedbed. However, the most unexpected catch was a Nathusius’s pipistrelle Pipistrellus nathusii that was found biting net 2. We struggled to take it out of the net but finally managed and proceed with the measurements. The overall color was paler than the Common pipistrelles I used to catch at Llobregat Delta and a slightly longer snout was also quite striking. the whole bat looked slightly bigger, probably due to the longer fur that is meant to have. The measurements fitted with the species: 53 cm. of body, 245 for the wingspan and 38 for the forearm. Despite what people usually says about bats, I still think they are beautiful…

Pipistrellus nathusii

Even I had been ringing for already 14 hours, the massive migration of crossbills pushed me to keep on going. Caroline was also encouraged, so we put up some nets south of the garden and, with the help of the speaker playing loud the crossbill-mix that Stephen had composed for the occasion, we managed to catch 1 Common crossbill. Several flocks landed just by the nets, but it was too windy and the pine trees too high. A Two-barred crossbill part of a flock of Common landed 2 m. from the net and what I saw like a lost chance became an encouragement for the day after.

Yesterday was a good day at Flommen (91 birds caught) but it was even better at Nabben. The migration counters managed to double both the Common and the Two-barred crossbill daily totals with 6580 and 51 respectively. We went straight to the Lighthouse and set the same net than the day before. It took a while for the crossbills to start landing but after a “fake” Two-barred we finally caught 2 “actual” Two-barred crossbills. One of them was still calling on its trumpeter style while I was taking it out of the net.

Loxia leucoptera

It showed some orange feathers in the breast, maybe pointing to a male.

leucoptera breast

The comparison between the 2 species was quite interesting. Apart from the fact that Two-barred is not as small as I had expected and the bill not as thin (just 1mm thinner than the Common!), a well-marked Common like the one we caught can cause some problems. Surprisingly, the bar in the median coverts seems to be the key. Half of the feather is white in Two-barred, but only the thin edge in Common. The tertials should be also useful, but I am slightly afraid of a Common with more white than that… A key feature that might work in the field is the wing tip: P2-P3 in Two-barred and P4 in Common. We may catch more in the next days so it will be interesting to study different ages. Yeah, I have to confess: a bright red male would be so cool…

loxia curvirostra barred ala

leucoptera wing


Riders on the storm

13 08 2013

“Cause it’s getting kind of quiet in my city’s head
Takes a teen age riot to get me out of bed right now.”

– Teenage riot, Sonic Youth

The catch has been really low in the last days, with just a few warblers of the three usual species. The weather has not helped the ringing and both the strong winds and the sudden showers (sometimes in the shape of thunderstorms) have turned the ringing into a high-risk activity. Even the tireless Southwest gangsters are showing some signs of fatigue… However, there are still some good points: the mosquitoes are blown with the wind and the temperatures are not as hot as last week.

lazy gangsters

Cycling (and therefore birding) is not pleasant and you’d better keep an eye into the sky if you don’t want to get wet: there are no raptors to spot, but it’s worth to keep track of the threatening dark clouds. Some of these summer storms are, nonetheless, beautiful.



Without passerines in the bushes, we’ve been looking for waders in the mudflats and the lagoons. A very nice juvenile White-winged tern foraging at Nabben among some Black terns, a Marsh sandpiper at Revlana and quite a few Broad-billed sandpipers seen in different places within the Peninsula have been the best of the last week.



Blast from the past

12 08 2013

“Dreams are the genus; nightmares the species.”

– Jorge Luis Borges

It’s been already 5 years with the same idea hanging around in my head. It was in summer 2008, already in July but after a memorable spring migration plenty of eastern migrants. Joan Castelló caught an Acrocephalus warbler at Reguerons, Llobregat Delta, that immediately struck him as being something different. His first impression while extracting the bird from the mistnet was of a cold-toned reed warbler, very small. Later on, already taking the measurements, he thought about Blyth’s reed warbler, especially due to the position of p2. The only problem he could find was, as always, the lack of emargination in p4. The bird showed a hint of emargination, but this is usually present in the subsequent primary to the one emarginated, due to a higher exposure of this part of the feather and therefore a differential level of wear.

We were afraid of the possibility of a Blyth’s with a non-emarginated p4, so we asked both Killian Mullarney and Anthero Lindholm, who kindly replied giving extra reasons for ruling out dumetorum. Both agreed the edges of GCs and the centre of the alula were too warm, the supercilium too colorful and the primary projection too long.

Fine, the bird was not a Blyth’s, but, then, what was it? Neither Joan nor me were happy with just “2cy+ Reed warbler” and, during the last 4 years I’ve been looking at the pictures again and again, without reaching any conclusions. However, the Acro world has been shaken in the last months, especially in its southern boundary. News coming from North Africa talk about resident populations of African reed warbler Acrocephalus baeticatus breeding north of the Sahara, as close to Llobregat Delta as Morocco and Tunisia. By that time this possibility was not taken into account but it’s now worth-considering.

The overall appearance is indeed that of a cold-toned acro, especially the head and the nape but also the upperparts. After a spring ringing in Falsterbo, Sweden, I am aware about how grey a Reed warbler can be, but Iberian birds are much warmer. In that sense, this bird was quite different from the ones usually caught in spring along the Iberian Mediterranean coast. The eyebrow was quite indistinct, something that we knew didn’t fit Blyth’s, and there is a noticeable open-face impression. The bare parts were also striking. Admittedly, the bill is not as dark as described for nominal baeticatus, especially in the under mandible, but the shape is more triangular than in a typical scirpaceus. The legs are much darker, almost even darker than in a juvenile Reed, with a more contrasted yellow sole. These legs would be, in fact, the darkest I’ve ever seen in a 2cy+ Reed.

acrocephalus sp3

The biometrics are the most striking feature. The wing length was 62, in the lower end of Reed warbler range according to Svenson. P2 is surprisingly short, falling between p5 and p6, far from the typical p3-p4 of scirpaceus. The emargination in p3 is very long, taking up 2/3 of the visible part of the feather. Moreover, the notch in p2 is also long, ending below the secondaries; according to Jiguet et al. 2010, the notch should end below p8 in a Reed warbler.  Finally, the wear of the primaries indicates that the tip is p4 and not p3 as typical in scirpaceus.

acrocephalus sp

acrocephalus sp2

All these features fit African reed and rule out Reed but, as always in the acro world, is not that easy! The most misleading thing is that those short-winged birds are quite common in the Mediterranean and Southern Iberia. I’ve caught birds with a wing length of 58 and there are several claims of Blyth’s reed warbler in Southern Spain that were identified based on biometrics. I’ve heard that some of those birds didn’t match all the features for Blyth’s, but this species was the most similar. I wonder if those ringers, as we did 4 years ago, forgot about baeticatus and, lost in Svenson’s bible, didn’t manage to find the answer.

The moult, the song and of course some feather samples should be the key. Although the moult of primaries in breeding grounds is a criteria for African reed warbler, BWPi already gathers some cases of Reed warblers moulting primaries in the Iberian Peninsula, before departing to the wintering grounds. Marc kindly sent me the photo below of a bird in active primary moult caught at Ebro Delta in early September and a bird with a very advanced primary moult caught in Northern Italy also in early September can be seen by clicking here (log in needed). Note that Marc’s bird also shows a suspicious wing formula.


Some evidences points to the fact that baeticatus, or at least baeticatus-like warblers, do occur at least in the south and east of the Iberian Peninsula but further studies are required to confirm this point. Keeping in mind the short distance from the nearest breeding grounds recently described, it wouldn’t surprise me if some birds are found to be breeding. The taxonomic debate may start soon and we shouldn’t be surprised if the final outcome is the description of another clinal variation from North (or even South) Africa to Eastern Asia, this time with Reed warbler as the principal actor.

Photos by Joan Castello © (1, 2 & 3) and Marc Illa © (4)

Waders night&day

2 08 2013

“I might as well open the window and kiss the night air.”

– Franz Kafka

We don’t have too much energy. After almost 2 weeks of ringing, the forces are already scarce since the cruel northern summer forces us to wake up at 3 o’clock in the morning. Therefore, when deciding what to do, you’d rather think twice if it would pay the effort. Moreover, the weather in the last days has not been so pleasant. Scattered showers, wind, foggy dawns… everything leading to an unpredictable and usually poor catch.

I had been told in the spring that this variable weather is good for waders so in the last days we’ve been focused mainly on this. The first night of wader and tern ringing was very productive, with more than 50 birds caught and some interesting species such as a first in-hand species for me: Sandwich tern. With almost no experience with them, the only thing I was able to notice in the field was the presence of “some” moult limits in the primaries. It looked promising and thought it deserved a better look; maybe it was time for me for finally tackling tern moult and ageing!

So, the first bird we caught showed 3 generations of primaries: P1 was growing, P2 was absent, P3-4 were the 2nd newest after P1 and P4-10 were the oldest, showing a decreasing gradient of wear. Both adult and juvenile Sandwich terns undertake a complete moult after breeding season, but juveniles doesn’t start with wing feathers until December, whereas adults start moulting them in July. Juveniles face autumn migration with entirely juvenile primaries, while adults have already moulted some. Both suspend the moult during the actual migration and carry on with it when reaching the wintering grounds. In the following spring, adults are done with the primaries and can afford a pre-nuptial moult that includes a variable number of inner primaries. Juveniles are still busy with their post-juvenile primary moult and don’t undertake any pre-nuptial. And then, what was this bird? After a really interesting discussion with Stephen, everything made sense: P1 belonged to this year post-breeding moult, P3-4 were pre-breeding and the rest of the feathers came from the 2012 post-breeding. Interestingly, the obvious step in wear between P5 and P6 is due to a suspension but not to a different generation of feathers. It’s worth to keep in mind P5 has another migration on its back! The final conclusion was that this bird must be a 3cy+.

Sterna sandvicensis 3+ restricted pre-breeding

The second bird we caught was also a 3cy+, quite similar to the first one, but with a much more extensive pre-nuptial, comprising P1-7. The 2013 post-nuptial moult had not started yet and even the head was in an almost complete nuptial plumage. All these evidences points to the bird being a late breeder: more time for a more extensive pre-breeding and a bit delayed in the post-breeding. The pre-spring migration suspension is probably between P8 and P9, what means the bird being in the wintering grounds until later than the first bird of the night (suspension between P5 and P6).

Sterna sandvicensis 3+

Sterna sandvicensis head

For making things crystal clear, the last Sandwich tern of the night was a 2cy. It showed also 3 generations of feathers but none of them was a pre-nuptial. P1-3 were 2013 post-nuptial but the subsequent primaries were not newer as in the other birds. P4-6 were much worner, what means they should come from 2012 post-juvenile. Surprisingly (or maybe not that so), P7-9 were really fresh, but this fact doesn’t mean they are pre-nuptial, but just the continuation of the post-juvenile. There is therefore a pre-spring migration suspension between P6 and P7. And yeah, as you might have already deduced, P10 is juvenile.

Sterna sandvicensis 2cy

Chapter two: Red knot. The day before yesterday I went to Revlana together with the gangsters trying to see some good stuff. The place was in fact packed with waders and terns. We’ve already seen some juvenile dunlins, but this wave of waders is still conformed by mainly adult birds in stunning summer plumage. I payed especial attention to Red knots, since there was an approachable flock composed by around 10 birds of different levels of plumage brightness. I focused on one of them and saw some really old feathers. Later in the evening, looking at M&P classical reference, we realized 1cy Red knots can moult some inner, some outer or all the primaries during the winter. Therefore, a bird showing a moult limit in the primaries now must be a 2cy but a bird showing a wholly uniform plumage can’t be safely aged as a 3cy+. If you look at the primaries in the picture below, it’s possible to see that the ones conforming the tip of the wing are much worner than the inner ones. Some tertials are also retained.

Calidris canutus2

detail moult red knot

Yesterday evening, encouraged by last night’ success, we came back to Möklappen for another night of wader ringing. This time, the catch was not as good, but a bright Red knot and some interesting Common terns were enough to keep us awake. The terns deserve another post (what are you waiting for, Stephen?) but, to carry on with the Knot thing, the bird we caught showed a moult limit between the pre-nuptial body feathers, scapulars and some coverts and the post-breeding coverts and flight feathers, but not the same moult limit in the primaries as the bird I had seen in the field. It’s interesting to notice how extensive the pre-breeding moult is, much more than any other Calidris species I’ve handled, since it can include even some GCs.  We finally aged it as a 2cy+ keeping in mind some juveniles can undertake a complete post-juvenile in winter. However, the timing in the moult of primaries of juveniles and adults might be different so, in case the rest of the variables were constant, it could be theoretically possible to age them by assessing the wear of these primaries.

Red kot in hand

Red knot wing

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