Robins and Chats – some comments on moult

It always pains me to complain about a book. I heard recently someone say, "any author of any book should be congratulated just for getting it published. Many people start writing a book but very few finish." – and it's true. Peter Clement should be wholeheartedly congratulated on the publications of Robins and Chats, the latest Helm Identification Guide. Chris Rose deserves equal praise for the plates, a lot of which I saw first-hand at the Birdfair. They're every bit a stunning as you'd imagine, particularly the rubythroats.

The problem I have is that my interests are, by my own admission, fairly narrow. I don't care about a species' behaviour, nor am I particularly worried about its status or distribution. When I buy a book like this, I head straight for the moult and ageing sections. I dream of opening the pages and finding something similar to Sylvia Warblers (also part of the Helm Identification Guides series): beautifully presented primary source data, the result of years of field work from the authors. What one gets with Robins and Chats, at least for the species I've thus far checked, is a re-write of BWP, Jenni & Winkler, and other material, mashed together in such a way that it becomes messy, ambiguous, and hard to sift through even for me. 

I've so far only dipped into a few species that I'm already familiar with – and in that respect I don't claim this blog post is anything like a full review of the book – but I'm already alarmed at how many errors there seem to be. Yes, they're small errors that only the most pedantic of readers are going to get worked up over, but they are still errors. Take for example the description for post-juvenile moult in European Robin: "Partial post-juvenile moult of head, body, lesser and median coverts, and variable number of greater coverts (usually innermost three, but possibly all in S Europe), also some or all tertials, and starting late May to mid-August, completed late July–early October". Ignoring the fact it's a pretty clunky sentence, I don't think I have ever handled a robin that has moulted any tertials. That's not surprising really given that Jenni and Winkler reported that 99.8% of the 8,499 birds in their study had moulted no tertials. Yet here, Robins and Chats implies it's the norm to see at least one tertial moulted on every bird following post-juvenile moult. 

And Common Redstart, "[Post-juvenile moult] affects head and body feathers together with lesser and median coverts and some or all primary coverts, in nominate all greater coverts may be retained from juvenile plumage or up to three inner coverts are replaced". Again, clunky; and, again, erroneous. Common Redstart, to the best of my knowledge (pers obs from a couple of hundred birds handled, and from published material) never moults primary coverts during post-juvenile moult. Robins and Chats references BWP and Jenni & Winkler within the Common Redstart moult section but neither of these make any mention of primary covert moult either. Of course it could be the author's own personal data but, if it is, it's a pretty casual way of describing what would be a radically different moult strategy to anything previously reported – and it would be interesting to know which population they were studying to get such surprising results. My feeling is, though, it's just wrong.

There's mention of primary covert moult in the Whinchat moult section, too. This, to be fair, is from previously published material (referenced here as BWP but in fact from an earlier publication that is quoted in BWP). However, it's pretty ropey and likely erroneous. My main issue here is that the claim of a small number of birds with moulted primary coverts (five from a sample of 30 in just one study) is taken out of context. The fact that Jenni & Winkler reported data from over 200 birds, none of which had moulted primary coverts during pre-breeding moult – and that the remainder of the BWP text reports a much more limited moult with no mention of primary covert moult – seems to have been swept under the carpet. The result is the misleading statement that "some" second-year (erroneously referred to as first-year in Robins and Chats) Whinchats moult all of their primary coverts during the pre-breeding moult.

Red-flanked Bluetail is described as moulting "some or all of tertials and tail feathers" during post-juvenile moult. The statement is made in regard to the overall post-juvenile moult of the species, thus implying it is the case in every individual. In reality, Hellström & Norevik (2013) found that just 1% of 397 had replaced up to nine tail feathers following post-juvenile moult and 1.5% had moulted up to all three tertials. So really, "tertials and tail feathers generally retained from juvenile plumage, may be replaced in very small number of individuals (Hellström & Norevik 2013)" would have been a much better way of putting it. What makes things even worse is that Robins and Chats doesn't reference Hellström & Norevik here; instead, it references BWP, which makes no mention at all of tail feather replacement! 

Further, the Bluethroat entry erroneously refers to post-juvenile moult of primary covers (again! I don't get the obsession with moulted primary coverts).

You'll be pleased to know I didn't have any issues with the Black Redstart moult entry...

And that's it. They are literally the only six moult sections I've read, five of which have errors (or, at best, misleading information). So what about the photo captions?

It's not unreasonable to expect birds in photos in a book like this to be correctly aged (or, in cases where they can't be, no age to be written at all). Forgive me for continuing to harp on about Sylvia Warblers but compare some of the photo captions there – carefully written mini case studies on the bird in question – with the minimal captions in Robins and Chats (below, screenshotted from Google Books).

European Robin, from Clement & Rose (2015). Robins and Chats,  Bloomsbury.

European Robin, from Clement & Rose (2015). Robins and Chats,  Bloomsbury.

Note the robin in the top right: "probably first-winter". Probably first-winter?! I wouldn't mind so much if this was a photo of a Rubeho Akalat or similar, where ageing characteristics aren't known or photos of correctly aged birds are hard to come by; but this is a European Robin!

At least in this case it was prefaced by "probably" (and it is a first-winter); there are multiple cases where the ageing is simply wrong. Two of the five male Black Redstart labelled as an adult are second-years; one of the "adult" Common Nightingale is a second-year, while the bird labelled "first-winter" looks distinctly adult-like to me; all three of the perched "adult" mourning wheatears (one lugens, one persica and one halophilawarriae is not photographed) are first- or second-years – and this is from checking through no more than about ten of the more familiar species.

To be honest, I haven't really read any further. I'd rather not know what other mistakes are lurking amongst other species entries. I fully acknowledge that few other people are going to lose any sleep over these mistakes and probably there's lots of stuff in the other sections of the book that is correct and well written; but it shakes my confidence in using this publication as any sort of authoritative reference. What happens if I need to find out the moult strategy for a species I don't know much about, like a Pied Bush Chat or an Eversmann's Redstart? Can I trust what I read?

What really makes me sad is that I doubt more than a few people will really notice. Or care.

Is this a book worth having? It's an attractive publication, the plates are very nice, and it appears to be the best single source for an overview of the family. Certainly, the general reviews I've seen have been full of praise. It's not a book I regret buying and I'm sure it will prove useful for lots of things; but, for moult and ageing, I've got a horrible feeling most of my references will be preceded by contra.

Robins and Chats by Peter Clement and Chris Rose Published by Bloomsbury, 2015, ISBN 9780713639636 RRP: £60.00

Cramp, S. (ed.) 1988. The Birds of the Western Palearctic vol. 5. Oxford University Press, Oxford.

Hellström, M. & Norevik, G. 2013. Further comments on the ageing and sexing of the Red-flanked Bluetail. British Birds 106: 669–677.

Jenni, L. & Winkler, R. 1994. Moult and Ageing of European Passerines. Academic Press, London.

Shirihai, H., Gargallo, G. & Helbig, A. 2001. Sylvia Warblers. Christopher Helm, London.