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Band-rumped Storm-Petrel - Ilya Maclean

Ilya Maclean

On the morning of 5th Sep 2022 I arrived at the Most Southerly Point at 07:20am, shortly after Paul and Joe. It seemed promising for seawatching, with approaching rain and strengthening SSE winds shortly after a previous storm. The season thus far had been exceptional, with high numbers of large shearwaters and an unprecedented influx of Wilson’s Storm-Petrels. A little while later Tony arrived, and he and I moved inside into the National Trust Wildlife Watchpoint hut. Though the field of view is a little restricted through the door, it is possible to get prolonged views without any scope vibration of birds approaching from the east, more than compensating for the lack of shelter from southerlies when outside.

As the weather started to close in (it was bright and sunny to start with), things were picking up, and about 08:25 I picked out a petrel flying westwards towards us in the Manx Shearwater line. I was immediately struck by its large and long-winged appearance and gliding flight action. From recent sea-watches, my brain was wired to look for Wilson’s among the more numerous European Storm-Petrels, and that was my immediate call. Watching as it flew towards me, I was puzzled though. Though Wilson’s is noticeably long-winged and has the characteristic gliding flight action, I find it quite a subtle bird to pick out from European. This was strikingly obviously different from European, and looked quite large and too long-winged for Wilson’s. I considered Leach’s, as structurally that was a better match, but it just didn’t have the feel of a Leach’s ÷ the flight action was completely wrong.

I was initially a bit stumped – I kept trying to fit the bird to Leach’s and Wilson, but it just didn’t seem to fit either, and it was only after watching it a while that Madeiran (Band-rumped) entered my head as a possibility, mostly on the basis of elimination – I had never seen one before and wasn’t familiar with the flight style. It was therefore with some tentativeness that I suggested this as its identity. Fortunately by that time Tony was also on the bird and was quite quickly able to confirm this having had the benefit of seeing quite a number previously. The bird passed quite close for a ‘seen-from-land’ petrel, and both Tony and I were able to get moderately good views of features. The guys outside, buffeted by the wind, had a much harder time finding it, though Paul did see it fairly briefly.

Band-rumped Petrel. This one taken by Tony Blunden at Banco de Concepcion, and not the Lizard bird, but the overall impression of the Lizard bird, was of a dark, long-winged Petrel.

The most striking feature of the bird was the flight action. Though often a bit variable, when watching petrels from land it is usually the flight action that I find the most useful clue to initial ID, and a striking feature of this bird was the prolonged sailing glides interspersed with shorter periods of wing-beating. When direction-changing it tended to do so when gliding rather than rapidly twisting and turning from side to side like a European Storm Petrel. It was this action that made me immediately think of Wilson’s Storm-Petrel, but aside from structural differences the flight action was actually rather different from Wilson’s, with stiffer wing beats somewhat reminiscent of a Fulmar or shearwater although faster. Overall it lacked the somewhat Hirundine feel of Wilson’s and was very different from the fluttery European, whereas I find Wilson’s to be more subtly distinct from European.

Despite structural similarities to Leach’s, it was the complete contrast in flight gliding style to any Leach’s Petrel that I have seen that made me initially think of Wilson’s rather than Leach’s. It is probably also for this reason that Band-rumped didn’t immediately enter my head as a possibility. I had no prior field experience of the species, and from second-hand accounts had always thought Leach’s to be the prime candidate for confusion. Despite structural similarities to Leach’s and initial confusion as to the identity of the bird, the entire time I watched it never really felt like a Leach’s. The flight action was altogether too purposeful, the shallow stiff wing beats quite different from the Black Tern feel that Leach’s tend to have. It always held its wings quite high and when beating downward, they never seem to drop right down in the way that I find Leach’s Petrel’s do (giving them their Marsh Tern or somewhat Nighthawk like-jizz). This impression was re-enforced a few weeks later, when I was fortunate enough to see several Leach’s Petrels from Horse Point on St Agnes – all were instantly identifiable as such and had a completely different flight style to the Lizard bird.

Some rather poor sketches of the bird in question, drawn shortly after watching the bird. Ilya Maclean

From the very first instance I saw it, it struck me as quite black and large for a storm-petrel, and while it can be quite hard to gauge size in isolation, I had seen quite a few European Storm-Petrels on the same fairly close line in previous days and also subsequently, and this impression was maintained the entire time I was watching it. Also very noticeable was the long-winged appearance, enabling almost instant dismissal of European as a candidate. On closer scrutiny it was also rather obviously larger and longer-winged than Wilson’s, which find harder to differentiate from European on wing length. In structure it was closest to Leach’s, but didn’t seem quite as elegant. It was only when the bird was quite close I was able to gauge the tail shape and I was initially a bit confused by this. On general observation it appeared not to have a forked tail, but on occasional directional changes seemed to have a fairly shallow but noticeable fork, particularly when banking.

Rump aside, the upperparts appeared fairly uniformly dark-brown, near black throughout. Only when it was closest and gliding was I able to make out any hint of contrast in the wings, but with the bird in motion I wasn’t really able to gauge exactly which portion of the wing exhibiting slight paler contrast, only that it was on the inner rather than outer wing, and didn’t appear to be on leading or tailing edges. Give the range the bird was at and the light conditions, had the bird been a Leach’s Petrel I would have expected to notice a more contrasting wing pattern, with paler greater coverts. However, ascribing confidence in the lack of a feature is always trickier than noticing the presence of feature, so this was more of a general impression than something I could see in great detail. Nevertheless, throughout, it maintained its impression of being rather dark and non-descript in its coloration. From most angles and even at distance, the white rump was obvious, but the contrast in the wings never so. Particularly when the bird was at its closes, I could make out that the rump was fairly ‘wrap-around’, extending downward to the undertail coverts giving it a House Martin like feel.

Aside from the extension of the rump downwards towards the undertail coverts, at distance the underparts also appeared fairly uniformly dark-brown, near black throughout, with no evident contrast to the upperparts. Though generally overcast when watching it, there was a period as the bird flew towards me at ~1000m range when it was quite illuminated by diffuse sunlight, and on this occasion I was able to see a hint of contrast in the underwing as it banked for one of its longer glides. Certainly, this was more of a hint of a contrast rather than clear white markings as one would expect to see on a European Storm Petrel.

Tony’s overriding impression was the bird seemed to be very consistent with Madeiran Storm Petrel (Oceanodroma castro) rather than other members of the complex. I have inadequate field experience of the complex to comment on this sensibly.

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