Wednesday, 16 March 2022

More Questions Than Anthus

Warning. Another niche post coming up...

Rock Pipits again. This is the sort of thing I never do, so I am somewhat in the dark re methodology. Still, it seems wise to get some stuff down in writing so that there is a kind of order about it all.

First, a photo of Rockit Land...

The best Rock Pipit habitat lies between the river mouth (top left) and the seaward end of Cliff Road (bottom left corner of the two pale fields) though I have seen them by the Hive Beach car park (bottom right) and on the holiday park (top left).

Yesterday was my fourth visit to the...ahem...'study area', where I have tallied between 7 and 10 Rock Pipits each time. I have photographed as many as possible, and discovered that they are individually identifiable by comparing tertials and visible coverts. As I have managed to photograph more right-hand sides than left, henceforth that will be my aim with every bird: get a decent snap at least of the right-hand side. Thus far I have pics of 13 different individuals. I have also identified one definite petrosus, though that ID is based on the assumption that only petrosus will be singing and displaying at the moment. And right there is my first question: is that assumption a safe one?

So, here are all 13 birds. A few are captioned where appropriate. The extent of subtle variability is rather surprising. At least, it is to me.

The first Rock Pipit I photographed (on 9/3) - next to the Hive Beach car park - and coincidentally the first photo too. Yesterday (15/3) the same bird was in subdued song and giving brief display flights by the end of Cliff Road. So, until I know different, this one is labelled Anthus petrosus petrosus.



Legs can look very pale in some lights. This individual has a lot of yellow on the bill, while on many birds it is completely black.


Nice to get a pic of the outer tail feather on number 5, which has an obviously pale grey wedge, but with some clean white on the extreme tip. Petrosus?





Those tertials are evidently not all the same age.

Another seemingly pale-legged bird. Very pale ground colour to underparts too. In fact, I would say it is basically white.

Rear views like this are dead useful for identifying individual birds, but can't always get them.


Again, the rear views of this bird show tertials are not all the same age.

Hopefully I will be adding to that collection in due course, but even the current total of 13 different birds is a bit of a surprise. Certainly there are more than I would have guessed. Also, that's the minimum count; I doubt I've photographed every bird present.

Questions then...

  • I have definitely photographed the same bird on different dates a few times, but is the current population resident and stable, or are some birds moving through?
  • Several of the photos appear to show evidence of moult in the wing. What does this indicate re age or subspecific ID, if anything?
  • Black bills. Bills with yellow on them. Does it mean anything? Should I care?
  • Leg colour. Is it significant in any way?
  • And the obvious one: are any of the above littoralis? And if so, which, and why, and to what degree of certainty?

Here's a bird which featured in the last post, having a stretch. Unfortunately I didn't (knowingly) manage a pic of the right hand side, so I don't know if it features above, but look at those outer tail feathers. They are definitely tipped white...


I would say with some confidence that this bird's left-hand outer tail feather is tipped clean white. The underside of the right-hand outer tail feather also looks very white, but I think this is misleading and prefer to stick to the upper side only when it comes to determining its true colour.

All these questions simply reveal to me how little I know. I don't own Pipits and Wagtails by Per Alstrรถm et al, nor Moult and Ageing in European Passerines by Jenni & Winkler, and what there is in my scant library is of little help. I briefly toyed with the idea of purchasing the above tomes (60-odd quid each!) before realising I would only be interested in a few pages, and came to my senses. Paul Chapman kindly sent me a screen-shot of a relevant page from Svensson's Identification Guide to European Passerines, which says this:

[Re petrosus] Pale portions on outer TF always greyish-white, never pure white.
[Re littoralis] Pale portions on outer TF greyish-white, or greyish white with purer white near tips.

Hmmm.

So there we go, that's the story so far. At the moment I plan to continue visiting regularly, and to photograph as many birds as possible. Ideally I shall continue into the breeding season, for obvious reasons. If the enthusiasm holds, I might even have a look for breeders a bit further west, along the cliffs between the mouth of the River Bride and West Bay, flanking Bridport Golf Course. But let's not get ahead of ourselves...

8 comments:

  1. Imagine how annoyed you'd be if you were just about to nail that crucial rock pipit image when you noticed a great spotted cuckoo flying past? Fingers crossed.....

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    1. I suppose the occasional nuisance bird is to be expected. ๐Ÿ˜Š

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  2. Firstly, what a sublime post title - bravo. Secondly, this is working up to be a really interesting project. I guess we'll get to hear the end results and conclusions in the Bridport Birder's ABR this time next year :)

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    1. Thanks Seth, and yes, the post title was just too tempting. Sadly my Rockit site is just outside the official Bridport recording area. And of course, BB has already asked for first dibs...

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  3. Hi Gav. Please see my posts -
    https://boulmerbirder.blogspot.com/search/label/Rock%20Pipit

    We get more littoralis than petrosus in winter but petrosus breeds on my patch too. In your shots you will always find birds that cannot be assigned in my opinion. No 4 is littoralis to me. They always have a better supercillium and because of this, less of an obvious eye ring than petrosus. The subtle greyer colour of the crown and nape often show out too. I never see grey Rock pipits with clean streaked breasts in summer. They are all the dark olive things that makes me suspect that most of the intermediate birds are littoralis too...
    Check my pics and see what you think...
    Cheers Stewart

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  4. Edit! Its Number 2 NOT 4... doh!

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    1. Thanks Stew. It strikes me that many (most) birds will be a 'possible' this or 'probable' that, but not identifiable with 100% certainty unless they acquire the littoralis breeding dress, or set up a territory on your local cliff!

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    2. PS. Ta for the links. Some useful pics. Especially like the 'Pipits on the Beach' post. ๐Ÿ˜Š ๐Ÿ‘

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