If you pay any attention to the world of zoological research (as you will do, given that you’re reading a blog called Tetrapod Zoology), you’ll know that the study of anatomy has very much come to the fore in recent years.

Previously bemoaned as a Victorian pursuit that had had its day and was inferior to the newer, shinier science of genetics, anatomy has been made ‘sexy’ by advances in CT-scanning, 3D visualisation and other new technologies. But it has also become widely realised that huge questions and areas of poor to non-existent knowledge remain as goes our understanding of anatomy and the evolution of anatomical systems in general.

Technical papers on such subjects as sensory organs in the heads and jaws of crocodiles and whales, the adhesion mechanisms used by geckos, the bite strengths of big cats, humans, bats and lizards, the flexibility of owl necks and numerous other anatomical topics have all been published lately, often with substantial media and public interest. A better understanding of big evolutionary patterns, most famously that between non-bird dinosaurs and the earliest birds, can also be considered part of this anatomical movement: it has inspired researchers to look at the transitions between groups, and hence, in the case of birds and other dinosaurs, to look in more detail at the mechanics, form and evolution of tails, limbs and feathers.

With all of this as background, picture now the publication of a gigantic, lavishly illustrated book dedicated entirely to avian anatomy and very much grounded in an evolutionary perspective. That book is Katrina van Grouw’s The Unfeathered Bird (Princeton University Press); I only have good things to say about it, and so do all the other people whose opinions I take notice of. There are already a huge number of highly positive reviews of this book out there in the blogosphere and elsewhere; if you’re interested in bird anatomy, or are aware of the book already, you’ll likely have seen or read some or many of them.

Very briefly, I’ll say that the book is huge (cover = 26 cm x 31 cm), its more than 300 sepia-tinted pages boasting an incredible array of van Grouw artwork (van Grouw 2013). Individual skulls and articulated limb skeletons, posed skeletons, muscle studies that look like x-ray visions of live birds going about their business, and anatomical illustrations of heads, feet, wings, tails and other parts feature throughout. The book isn’t just composed of pictures, however. A substantial text describes the bird groups and their key behavioural and anatomical modifications, providing enormous insight on functional morphology, anatomical minutiae and form-function correlation (van Grouw 2013). It is simply imperative that you get hold of this book if you consider yourself interested in bird anatomy and diversity, or in anatomy or evolution in general. [Image below from John Hutchinson's review of The Unfeathered Bird.]

The Unfeathered Bird would be a remarkable and noteworthy book at any time, but I think that part of its success comes from the fact that it has appeared at a time when an interest in anatomy, in an improved understanding of bird evolution and ancestry, and in an appreciation of avian anatomical weirdness and innovation are at an all-time high. Given that the book has been widely praised by palaeontologists who specialise on Mesozoic dinosaurs, I suspect that the sheer celebration of bones, skeletons and functional morphology is a major plus-point... with apologies and due respect to biologists who work on living animals, all too many people who study birds often seem uninterested or uncaring about the nuts and bolts of anatomy, as if genetics, behaviour and ecology are all that matters. As I said previously in my review of Gary Kaiser’s The Inner Bird (Kaiser 2007, Naish 2011), books devoted to bird anatomy are just about non-existent. And, while I think very highly of Gary’s book, one of its weaknesses is a lack of illustrations.

Anyway, rather than just wax lyrical about Katrina and her work, I’ve been given the opportunity to do something rather different. I’m in the lucky position of being in relatively close geographical proximity to Katrina (we both live in southern England), and I was recently invited to visit Katrina and her husband Hein at their house. The article you’re reading now is thus more than just another review of The Unfeathered Bird, it’s a (hopefully) unique, behind-the-scenes look into Katrina’s work.

And so it was that, some time several weeks ago, I travelled from my secret London base to Aylesbury, home of the famous van Grouw...

A visit to Katrina’s

We go to the pub, we go for a walk in the woods (Katrina’s dog, Feather, amuses me by taking a bath in a giant puddle of mud, just in time for her trip back to the car), and I accompany Katrina as she takes one of her illustrations – the one featuring the Great hornbill Buceros bicornis (how apt!) – to a framers. It’s being framed for display at an exhibition, thus beginning a nice story arc that will be completed at the end of this article.

At her house, I meet Katrina’s ornithologist husband, Hein. Hein keeps pigeons and shows me the several different kinds he keeps and breeds. There are Jacobin pigeons, with their absurd neck ruffs and bizarrely long primaries, and fantails, some of which are so-called silkies: pigeons where the feathers have a weird, ‘decomposed’, messy appearance caused by the absence of the barbs that normally keep the feathers neat, tidy and with a sensible aerodynamic form.

Hein has been running various hybridisation experiments on the pigeons, crossing the different breeds in order to learn about the expressions of the genes involved in creating their weird feather forms. Nothing is as simple as we might have assumed a few decades ago, the possible role of epigenetics complicating our ideas about the expression of traits. The weird feathered feet of some of the pigeons has Katrina, Hein and I wondering all sorts of things about microraptors and other ancient relatives of birds.

Katrina and Hein’s house and garden are, together, a packed museum or theme-park of zoological awesomeness, designed to make people like me swoon with awe or fume with jealously, I’m not sure which. Still in the garden, and I see their impressive collection of muntjac deer skulls, so we stop and speak about the evolution of antlers. Katrina and Hein keep ferrets, so we speak about the role lifestyle has on mustelid skull anatomy. Indoors, and I get to see whole cases and display cabinets dedicated to mounted and posed bird skeletons (wild and domestic), many or most of which look like old friends since they are the exact models Katrina illustrated for The Unfeathered Bird (more on that in a moment).

If your memory is good, and if you’ve read The Unfeathered Bird, you may recall the book being dedicated “To Amy”. Amy is (or was) a mallard, her mounted skeleton and glass case being one of the first objects I encounter as I enter the house. Close to Amy are cabinets of posed skeletons that have been collected and mounted for Katrina’s in-progress project on domestic animals (more on that in a moment, too). A skeletal toy poodle, domestic cat, and variety of chickens and pigeons occupy another cabinet in another room. Then there’s the library. Shelves and shelves of the Poyser bird books, numerous (most, or all) of Birds of the Western Palaeactic and Handbook of the Birds of the World, and so on.

Encountering the art

And then – the art! I finally get to see, in person, the originals of many of Katrina’s pieces, including the famous peacock skeleton that features on the book’s cover, and – awarded centre place in Katrina and Hein’s front room – a giant study of a skeletal Mute swan.

Then, there’s the new stuff. I’d read an article in which Katrina had told of her plans to illustrate both the late anthropologist Grover Krantz, famous for his serious and long-standing interest in Bigfoot (Krantz 1987, 1999), together with his beloved Irish wolfhound, Clyde. The bodies of both were donated to the Smithsonian Institution after Krantz’s death in 2002, their skeletons mounted in a pose that mimics one they adopted for a photo taken in life. This is wonderful – both brilliant on an intellectual level and moving on an emotional one – and exactly the sort of thing I love seeing at museums. Unfortunately, there are some anatomical errors; my understanding is that Katrina is set to ‘repair’ them in an illustration, the Smithsonian then using this as a guide to remount Clyde’s skeleton.

This crossover between Krantz and van Grouw is an unexpected surprise. Hey, Krantz wasn’t exactly an intellectual hero of mine, but, having read his bigfoot book, various of his papers and articles and a lot of material about him, I do feel as if I ‘knew’ him, in a way. I meant to bring along my copy of Krantz’s Bigfoot Sasquatch Evidence to show to Katrina, but forgot. I was to learn of other curious and delightful crossovers involving Katrina and other people from the TetZooverse...

Katrina shows me drawers full of illustrations, some I know from the book, others of which are wholly new to me. I know the pictures in The Unfeathered Bird reasonably well, so it’s weird to see them ‘in person’. Many are startlingly large, but, then, they would be, since many (or all? I’m not sure) show the birds at life-size. The other crossover surprise is revealed as Katrina pulls out her drawn-from-life illustrations of the Sperm whale Physeter macrocephalus that beached on the coast of Pegwell Bay, Kent. Regular readers will know that I’m a big fan of Inside Nature’s Giants (I wrote about all the episodes of series I back when they were screened for the first time). So, while the ING crew (Joy Reindenberg and so on) were there on the beach, dissecting the whale, Katrina was watching and drawing. Neat.

Bones and bones and bones

I mentioned those cabinets of skeletons. I try to be polite and not gawp idiotically at them for too long, or look as if I’m taking too many photos. I may or may not have succeeded, I don’t know. Before visiting, I’d wondered how Katrina creates the illustrations that she does. Like an idiot, I’d assumed that she looks at live birds before imagineering a sort of x-ray version that has the bones (or muscles or other structures) pictured in place. Nope.

Katrina and Hein have amassed many bird skeletons, all obtained (via absolutely legal and ethical means) at the carcass stage from bird parks or private collections, or picked up following natural deaths in the wild. Hein has prepared and cleaned these specimens from scratch, “boiling most of them on the kitchen stove”, Katrina tells me. And cleaned animal skeletons don’t generally come in posed, fully articulated form – you have to position them yourself, using wire and frames and so on if you want them to be in life-mimicking poses. It turns out that Hein is a world-class expert at this, and it is these mounted skeletons that are the models that Katrina has drawn from.

There are owls and parrots gripping and clambering on perches, a budgie peering into its favourite mirror, a woodpecker clinging vertically to a branch, a peacock bowing in display, and so many others. All are wonderful. I don’t know where to start so end up looking at virtually none of them. If you own The Unfeathered Bird, you’ll recognise some of the mounted skeletons you see here. Wouldn’t it be incredible if you could see those same skeletons yourself, in a museum or something? We’ll come back to that.

Coming soon: the domesticates!

Heavily hinted at in The Unfeathered Bird is Katrina’s interest in the anatomy and diversity of domestic animals; the great, surprising variety in these animals really needs to be taken more seriously, not neglected or ignored because the creatures concerned are ‘unnatural’. We’ve bred lizards that lack scales, pigs and cattle that have conjoined digits and horse-like, non-cloven hooves, cattle with bifid neural spines and gargantuan, swollen horns, and ‘silky’ birds that have ‘loose’ feathers that lack the anatomical bits and pieces that ordinarily help feathers maintain their form. These are all curious – sometimes major – anatomical innovations, yet selective breeding has allowed their expression after just a few decades or less.

Katrina tells me of the plans for her next book, devoted entirely to the world of domesticates. Needless to say, there’s the danger that this project will become one of those Sisyphean tasks, its scope and size being something like a person’s life work, not the subject suitable for a single volume. And, already, Katrina has decided not to embark upon the path of discussing the animals on a species-by-species basis, but to focus on major themes and trends within domestication. Assuming all goes to plan, this work will appear in January 2018: 150 years after the publication of Darwin’s Variation of Animals Under Domestication. I can’t wait to see this project come to fruition. It being a Katrina van Grouw project, it can safely be assumed that it’ll feature amazing images of posed skeletons and x-ray-style images of musculature.

But – waitaminute. We’ve all seen the skeletons of innumerable animals in museums and other such places. But how often have you seen mounted skeletons of domestic animals? There’s the odd chicken, duck, horse, cat or dog skeleton here and there, but they all belong to standard, widespread breeds. The concern, then, is that it might actually prove very, very difficult to obtain skeletons of the more obscure, rare or atypical breed. Furthermore, an annoying snobbishness about domestic animals – they are, so the thinking goes, merely ‘dogs’ or ‘sheep’ or ‘pigs’ not really different from all the others – means that museums and the people behind them have often not considered these animals worthy of study or of being incorporated into, or retained within, collections.

Despite these issues, Katrina and Hein have managed to obtain a lot of required material already. I get to see the skulls and skeletons of various obscure sorts of sheep, dog and pigeon. Some skeletons are still disarticulated, kept tidily in boxes and waiting for assembly. They create the irresistible impression that you might be able to buy your own Munchkin cat skeleton for assembly like an airfix plane kit or lego set. You can’t.

At the time of my visit, it seems that there are still quite a few domestic animal breeds that Katrina aims to get her proverbial hands on. We speak about double-muscled whippets and about Whisky, last of the Turnspit dogs. Believe it or don’t, 17th and 18th century kitchens in Europe used these small, short-legged dogs to turn wheels (bolted to the wall) and thereby keep spits rotating in the fireplace. Turnspit dogs had had their day by the 1860s and faded into oblivion thereafter, eventually becoming extinct. If this is all new to you, I appreciate that it might sound like fraudulent nonsense. It is not (Bondeson 2011).

The Unfeathered Bird: a lengthy backstory

The tale of how The Unfeathered Bird came to be is long – years long, involving failed deals with various publishers. In the end, the publishing of the book through Princeton University Press came about, Katrina told me, due to a chance meeting with a publishing executive in a pub. Had she not gone to that pub, or been introduced to that person, I suppose a real possibility might exist that the book would still not be out. I’ve had very bad luck with publishers (it seems that just about everyone involved in publishing has stories of this sort), but they’re nowhere close to Katrina’s story in duration and heartbreak. And, as if getting the book published might seem like a happy end to a long, frustrating adventure, there’s more.

The events surrounding what happened as goes Katrina’s position as the (former) employee of a major natural history museum are sad and a bit weird. Despite knowing of Katrina’s plans to produce a bird-themed book at the time of her initial employment, the museum later let on that they had a strict policy of not letting employees produce natural history-themed books, even in their own spare time. Now, I can very much understand why a museum (or other institution) would not want employees to write books during work time, but… surely people are (essentially) allowed to do what they like in their own time? Katrina never used specimens from the museum collections during the preparation of her book. She eventually left of her own accord, knowing that the book’s publication would cause problems. I still cannot quite get my head around the way things panned out.

Anyway, as goes the final product itself – I mean, the book – I think my feelings are already clear. This book should be cherished and enjoyed by people interested in birds alone, or in anatomy, evolution or animal diversity in general (hmm, I think I already said this). The birds are arranged according to the Systema Naturae of Linnaeus, a decision that might raise some eyebrows but which was chosen to show how convergent evolution has shaped avian anatomy. Opting to follow this particular scheme also removed the need to follow one or other recent phylogenetic arrangement, a sensible decision given the 25 year gestation of the volume. Naturally, there are places where the text – while referring to certain hypotheses of affinity – does not reflect the views favoured in the most recent studies. To take just one example: owls are noted as possible relatives of nightjars (p. 44), whereas recent work actually puts them close to trogons and piciforms (e.g., Hackett et al. 2008).

Anyway, I’m extraordinarily grateful to Katrina and Hein for their time, kindness, hospitality and assistance, and for the opportunity to produce the article you’ve just read.


Some time after my visit, I got to see an entire museum gallery devoted to The Unfeathered Bird. The gallery in question is at Buckinghamshire County Museum in Aylesbury and remains there until late September 2014. I attended in May and was blown away. Whereas many or most of Katrina’s pieces of art were stored or stacked up against walls during the time of my visit, I now got to see an entire gallery devoted to them, displayed in all their beauty, framed, on the four walls of the room. Among the many was the Great hornbill illustration that Katrina had been arranging to have framed when I visited her. Arranged about the room are glass display cases housing both some of the mounted skeletons referred to above as well as taxidermy mounts of some of the species depicted in Katrina’s illustrations. For a fan, this was a huge treat.

I hope you enjoyed this van Grouw-themed article, and I assure you that it won’t be the last time that Katrina is mentioned or discussed here at Tet Zoo.

van Grouw, K. 2013. The Unfeathered Bird. Princeton University Press, Princeton and Oxford, pp. 287, ISBN 978-0-691-15134-2. Hardback, index. Here at amazon.co.uk, here at amazon.

For previous articles on bird anatomy and various of the issues mentioned here, see...

Refs - -

Bondeson, J. 2011. Amazing Dogs: A Cabinet of Canine Curiosities. Cornell University Press, Ithaca, NY.

Hackett, S. J., Kimball, R. T., Reddy, S., Bowie, R. C. K., Braun, E. L., Braun, M. J., Cjojnowski, J. L., Cox, W. A., Han, K.-L., Harshman, J., Huddleston, C. J., Marks, B., Miglia, K. J., Moore, W. S., Sheldon, F. H., Steadman, D. W., Witt, C. C. & Yuri, T. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 320, 1763-1768.

Kaiser, G. W. 2007. The Inner Bird: Anatomy and Evolution. University of British Columbia, Vancouver, Toronto.

Krantz, G. S. 1987. A reconstruction of the skull of Gigantopithecus blacki and its comparison with a living form. Cryptozoology 6, 24-39.

- . 1999. Bigfoot Sasquatch Evidence. Hancock House, Surrey, B.C. & Blaine, WA.

Naish, D. 2011. [Review of] The inner bird: anatomy and evolution. Historical Biology 23, 313-316.

van Grouw, K. 2013. The Unfeathered Bird. Princeton University Press, Princeton and Oxford.