Knee tremblers and wing runners!

Having dwelt on seawatching numbers in a previous post, thought I say something about those few ‘rare’ encounters; well one species group in particular. So what’s my best off Devon? For me the real ‘knee trembler’ is seeing a Pterodroma! Though I’ve seen seven (and one that got away, more on that later) off Britain and Ireland (3 Devon, 4 Ireland); that’s more than Barolo Shearwaters (3; 1 Devon, 2 Ireland) or Yelkouans (2 Devon), yet they're more exciting! There’s just something about the way they fly and look puts them right at the top of the pile. Pterodroma, the name says it all, from ancient greek pteron, "wing" and dromos, "runner", reflecting their remarkable effortless flight action.

We saw the first accepted Pterodroma for Devon pass Prawle Point on 17/08/1999, but in awful weather and far too briefly (c10 seconds) to really appreciate it. We actually submitted as a Pterodroma of the Fea's / Zino's / Soft-plumaged Petrel group, in those days Soft-plumaged Petrel was still being used to describe UK and Irish birds. It was accepted as a Zino’s / Fea’s Petrel - yes back to that in a minute. Despite that bird being too brief for a real ‘knee tremble’; it was still a momentous occasion for the five of us who saw it, which Matt Knott nicely wrote up in DBR1999 p167–168.

My second at Berry Head on 17/07/2001 was a different experience altogether, much better views, better weather and seen for a longer period (5 minutes, to appreciate it) with Mike Langman and Bill MacDonald. Mike and I picked it up simultaneously well to our north in Lyme Bay, with two Manx heading in towards us. I can still remember suddenly seeing that graceful yet dynamic flight and yes the ‘old’ knees immediately going into the ‘Pterodroma tremble’. So much so I struggled to get the words out, mumbling “**** you better get on this”. This bird was clearly bigger (longer-winged) than the accompanying Manx. One of the reasons we actually submitted as Fea’s Petrel (based on size etc), but it got accepted as Zino’s / Fea’s Petrel. Four more followed from visits to Ireland in 2006 and 2007, again each time I saw one, still that rush of adrenalin. The three Irish birds in 2007 were made even sweater with the realisation Del and I managed to clock the first, second and third sightings for County Mayo! Yet each time that real buzz of pure excitement that just doesn’t go away with the next one. My final UK bird (so far, here’s hoping) was again at Prawle Point on 31/08/2009, this time on my own and seen for 10 minutes as fairly well out, but picked up coming from well to the east and continued to watch until is disappeared into the west. It still invoked the ‘Pterodroma tremble’, after which I rushed up to Prawle village to get a mobile signal to phone it in, hoping to give others a shot at it further west along the coast. It went past Porthgwarra right on cue, some  5 hours 21 minutes later, giving those present a chance to appreciate the ‘Pterodroma tremble’, or as Russ Wynn there at the time described as ‘dribbling and swearing’. I suppose they have different effects on different people! What also makes these birds so magic on a seawatch is, they just don’t hang about and after that brief view (a few minutes if you’re really lucky), they’re gone and you’re left wanting more, or thinking did I really see that!

Well a few years have passed and I’ve not been lucky with another off Devon or even trips to Cornwall. I felt myself going into some sort of Pterodroma withdrawal (well save the one we’ll visit in a minute). There was only one remedy, I just had to go to Madeira and indulge myself in the Wind Birds pelagic trips, following in the footsteps of seawatching friend, the late Dave Norman and so many others. I’d heard so much good talk about these trips, with the added possibility of seeing both Zino’s and Fea’s (Desertas) Petrels. Definitely on a seabirders must do list!

So I completed the Wind Birds amazing three days of pelagics during 26/05/15–28/05/2015. I had great views of many tubenoses, including seeing three new species. But you know what, for me the best were those Pterodroma sightings (and White-faced Storm-petrel of course). Even out on a boat you get that absolute buzz when one turns up, usually just all too briefly as it investigates the chum slick before just disappearing again back out into the ocean. It was great to actually see Zino’s Petrel in the field and although I should have taken a lot more photos, I preferred to watch and savour when one turned up, rather than having my eye buried in the back of a DSLR all the time and missing the action. Although we saw Pterodroma petrels that could not be specifically assigned to either Zino’s or Fea’s (Desertas) Petrels, I found both the ‘good’ Zino’s we saw to be more delicate birds than the ‘good’ Fea’s, with a lighter feel about them and how they flew, being more Manx sized - even before critical stuff like bill size (and underwing) was analysed from photos. Now thinking back to my few UK and Ireland sightings, though they’ve all been accepted as  Zino's / Fea’s, not one of them (based on my Madeira experiences) could I say best fitted Zino’s. Those seen well and in company of other seabirds for size comparison have all better fitted Fea’s. When you think the few positively identified birds so far off the UK (all photographed) have been Fea’s, Zino’s does seem to be the less likely (especially considering relative population sizes), although as with all seabirds anything is possible, as a Bermuda Petrel off Ireland and Soft-plumaged Petrel off Norway show. But heck in bird reports with this particular species amalgam the Zino's bit comes first (taxonomic order!), Zino's / Fea's. It’s a bit like seeing Cory’s Shearwaters off Devon, there’s a remote possibility we may overlook a Scopoli’s Shearwater (and we’d need a good photograph to get one accepted), but we’re still calling them Cory’s Shearwater (and in the bird reports) as the most likely and not Cory’s / Scopoli’s Shearwater. Of course many of the Cory’s I’ve seen off Devon were sufficiently good views of the underwing to be fairly confident they were Cory’s, but many weren't (but separable from Great of course). Anyway going back to main subject, a Pterodroma sighting is still a magic event whether you can go down to species or not.
A very rare Pterodroma! A 'good' Zino's Petrel, on jizz in the field, structure, bill etc, but with a dark underwing coverts scoring 0–1 (in the overlap underwing score with Fea's, its still a Zino's) and below the other extreme.
A 'good' Zino's Petrel, with a pale underwing coverts scoring 4 (zone with little overlap with Fea's, so more clear cut as a fly past). This would be quite distinctive passing one of our headlands - if only!

That brings me onto one that got away. On the 02/10/2012 I was at my favourite Devon seawatch headland. Conditions were ideal with a SSW 5, increasing SW force 6–7 and murky horizon. There was an exceptional Sooty Shearwater passage underway; I ended the day with 326 birds - Devon's second highest count (also 82 Balearic Shearwaters). An excellent watch in itself, however, at 10:15 I saw a bird that completely stumped me at the time. It was a fair way out, moving through with Sooty Shearwaters, so in direct comparison very similar in size. When I initially picked it up I thought I was looking at a slim dark phase skua (like a dark juv Long-tailed in shearing flight). I've seen Long-tailed shearing before many times (including many trips watching the passage off North Uist), but then the flight of this bird was far more dynamic and not a skua! That initial thought of skua was because the bird was a cold dark brown and lacked the silvery underwing (though the coverts) of Sooty Shearwaters (many for comparison), any pale on the underwing was restricted to just the base to the primaries (underwing), it also lacked the longer necked, smaller headed look of Sooty, being shorter necked and slightly larger headed. The similarity of the attenuated rear end of Long-tailed skua, almost a wedge-tailed appearance was also notable! The more I looked at it the more I was convinced it was a dark Pterodroma sp. That effortless flight, several times it towered up (yes Sooties do that), but with little effort and hardly a flap looking more buoyant, to be easily lost on the down glide against the sea to reappear again towering up. At one point it looped completely back on its flight path in typical Pterodroma fashion. At this point I went into the ‘Pterodroma tremble’ and after it had gone I gathered my thoughts made some notes and phoned fellow seawatching friend Mike Langman. I was certain it was not a Sooty (I’d seen a quite a few) and not a skua. I knew it was something very good, but I also knew realistically I wasn’t likely to ever do anything with it (too far out for a photo which you will need for an extreme rarity) - but what was it likely to be? In early 2013 I purchased Steve Howell's (then new) ‘Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide’. In this excellent book I found something that matched my bird. Pictures and description of dark morph Trindade Petrel! I also hadn't realised they were regularly occurring in the west North Atlantic!! Later in 2013 I also purchased Bob Flood and Ashely Fisher’s superb ‘Pterodroma Petrels’ multimedia guide. Again Trindade Petrel was the best fit. So I bucked up the courage to email Bob about the sighting, saying not enough to go any further but what were his thoughts? I received a very positive reply, which concluded this was the most likely candidate, as fairly regularly occurring off North Carolina (and a few Azores) and to date c. 70% in the North Atlantic have been dark morph! He went on to say “When I read your description of 'that bird' off Start Point, it resonated strongly with my experiences of Trindade Petrel”!

Had somehow a Trindade Petrel go caught up in the same Atlantic conditions that had brought in this massive movement of Sooties to the Western Channel? Of course I'll never know!

But alas for me a Pterodroma that got away. Seems the UK has had a few close calls with this particular “knee trembler”, I hope one will be seen well (and photographed) sooner or later and added to the British list!
Notes on that bird. I'm no bird artist, looks like I've drawn a skua, but it weren't no skua!


  1. Great post, Mark. While I've never had a seawatching knee-trembler to match these monsters, I live in hope! Though I'd probably need to put a bit more time in first...

  2. Cheers Gavin, at least you had knee-tremble and some with that Pike!! But there's always hope I remember the survey boat we used kept in West Bay had a Fea's fly over it (a bit further out) and twas accepted for Dorset!

  3. Great read Mark, there will always be the odd bird that gets away especially for seawatchers. It is about time we had another Fea's at Berry Head - perhaps in 2017..

  4. Thanks Mike. Yes,I've had a fair few that got away, like the Berry Head [Wilson's] Storm-petrel sp.....and like you I'm quite happy to note skua sp. and large shearwater sp. Its the very nature of seawatching we cannot identity everything and perhaps that makes it even better. Yes, well overdue another Fea's, and you know where I want to see it!

  5. Great post Mark - the Prawle bird is forever etched in my memory but my knees were trembling through cold and discomfort as I remember, such was the brevity of the sighting. You've done incredibly well for Feas/Zinos - only a matter of time before the next one....

  6. Cheers Matt, in my book you're King of the 'knee tremblers' with the amount of stuff both you and Mike L has found. In fact I was lucky to on the scene (seawatching), when Mike found his Blyth's Reed Warbler in the quarry, on reaching him from the seawatch point I detected he was in quite a tremble with that one - quite right too!

  7. Hi Mark, you'll know about the Dungeness Trindade P in '98 of course, did you know Martin Elliott had a similar bird from PG a few yrs back. Showed me his sketches and no doubt in my mind it was a Trindade. Sooner or later there'll be a photo. I had my own WTF bird in '97 at Pendeen, convinced it was a Pterodroma on shape and flight but with a very white underwing, never did figure out what it was - though I have some fairly outrageous ideas. Might write about it some day.

  8. Hi Tim, yes I read about both the Dungeness and Martin's bird. On present accepted records in W North Atlantic the dark ones seem the most regular, so interesting these weren't! I remember a friend of mine being with Pete Harrison when they had one go by Pendeen. Please do write-up your 97 Pendeen WTF bird - on your blog! I for one would like to read about it and what you though the candidates might be!