Open letter to Chris Packham following episode 12 of The Wonder Of Animals – Birds Of Prey
Hi Chris –
Great series. I caught about half of it but will watch it all again eventually. It taught viewers including me such a lot, but there were a couple of things in the final programme that weren’t quite right:
No air actually passes through bird bones (we can trust Duncker), and definitely not as part of standard breathing. There’s no mechanism for sucking or blowing through the bones, and no known reason to do it. My brief hint of it, extracted from my chapter 7 is here. They do have air in them for lightness, and as I think you said, that’s not the same reason they have air sacs, which allow one-directional flow. (Crocs also have one-directional flow without airsacs as such, though they do actually have the same amount of air in them as birds. It seems even lizards have the one-way loop.) There’s a lot of new stuff about bird breathing that could do with being explained to the public and hasn’t been yet.
Also, though you rightly mentioned that falcons are more closely related to parrots than to other birds of prey, what is not commonly appreciated from Hackett et al, 2008 and the other studies (and usually not even by the authors of the studies), is that birds of prey do probably form a single group – it’s just that most other landbirds are inside it. They’re ex-birds-of-prey! There is no reason to suppose that all the special features that falcons and hawks have in common are independently evolved. Polly parrot is closer to falcons than hawks are, but birds of prey are just Parrot-phyletic (paraphyletic), not necessarily Polly-phyletic (polyphyletic).
My brief posting on that is here.
Notice that birds’ of prey’s ratchet mechanism for claw-locking illustrated in the programme, is reminiscent of the locking mechanism in the feet of perching birds. This single feature works to unite perching birds (considered by the Hackett 2008 study hinted at in the programme to be the sister group to parrots) with not just falcons but non-falcon birds of prey too. This then serves to unite perching birds along with both falcons and other birds of prey, into the same taxon. Yes that could theoretically have been a bit of parallel evolution, but don’t bet on all the adaptations shared by birds-of-prey being parallelisms. [Images below from BBC. Click here for origin site. Episode may be unplayable.]
All this and much much more is covered in my book – essential and entertaining reading for the likes of you. If I thought you would read it, I’d even send you a free e-copy. I do guarantee it would be one of the three most fascinating books you’ve ever read. But I also guarantee to publicise enthusiastically any scientific errors caused by your continuing irrational ignoring of it.