Monday, June 04, 2007

Unqualified praise...

...from the comments... re the 24th May compelling Ivory-bill contact
Ford Madox Ford Madox Ford said...

Quite a comparison there between the IBWO and the WTD, apart from the WTD squiggles being shorter, and thinner, and differently shaped. Damned conclusive, I'd say! Good work!

I like it when people praise my work, and I am too naive to spot sarcasm. FMFMF must have been too impressed by my kents to check the scales of the WTD bleat and FL 'kents' because they are the same length. Thinner is just the parameters of the sonagram contrast and brightness, prob nothing to do with the calls. Different shape I will buy. But then again... here is a sonagram of some real kent calls from the archival audio here. Thanks to Syrinx

Don't get me started, but I'm really not sure that these are a better match for the FL kents than the deer. The shapes are better, but the frequencies are wrong and the calls of the real IBWOs are too short. I'm happy to accept that the WTD bleat is not the same as the FL kent, if by the same token we accept it is unlikely that the FL kents are the same as the IBWO kents.

While I'm here... I said don't get me started, but now I've started... look at the now-infamous wingbeats at 1.6-2.6 seconds. There is NO WAY that bird is tanking away from the microphone like the Luneau video bird. Think of the ground it would be covering - the flaps would fade away to nothing, but instead what there is here is 9 flaps of relatively equal amplitude, that stop suddenly. I think it's very likely that this bird was just fluttering its wings, or at the most going between 2 branches in a tree. Not comparable to Pileateds or IBWOs in level flight Apples and oranges :-O

Btw, if I remember my 20 year-ago lecture notes properly, as birds get bigger, mass increases as a function of length to the power three, whereas wing area only increases as a function of length to the power two, so bigger birds, all things being equal, tend to have more mass to be carried per unit wing area than smaller birds. To compound that, my understanding is that most of the lift provided by a wing is a function of the length of the front edge. That's why bigger birds eg IBWOs have proportionately longer wings, narrower to reduce drag, than smaller birds e.g. PIWOs. They gain lift at the expense of the manouevrability afforded by broader shorter wings

A big bird like IBWO has a mechanic problem about how to maintain lift cf a smaller bird like PIWO. According to Gill's textbook, 'Ornithology', what I was reading the other day, in general birds increase lift by increasing flight speed - not by flapping faster. There are exceptions when there are other constraints on the wings (e.g. Auks) but in level flight energy considerations mean that in general big birds will in fact flap more slowly. The bones and tendons for the wings act as a pendulum which resonates to minimise energy use during flight. Long wings are longer pendulums with an inherently slower natural frequency. So intuitively I would expect an IBWO certainly to fly faster than a PIWO, but I can't think why it would flap faster. Indeed this would go against the trend for other N american woodpeckers, for which (as I remember - correct me if wrong) the Tobalske work showed that in level flight the flap rates slow down with increasing size.

Other things... if the 2006/7 Florida search really has failed (6th June update) , I think that reduces the chances of Ivory-bills being alive to about 0.1%. if I'm generous, which I am.
I was reading Hill's 'Ivorybill Hunters' and enjoying it very much, from a birding perspective - can't fault the effort. Can't help but like the folks involved either. Future ornithology archaeologists will sift through the bones of that book and try to reconstruct how expectation alone could bring a bird back from the dead.

Double knocks could be Gadwalls smacking into each other in flight, apparently. Now that would be funny to see.

Other things that would be funny to see - I did see them, but you didn't so I will describe. On the way back from Peterborough on Saturday night, two blokes got onthe train at Dundee and one of them was so drunk he hadn't noticed his pants were on fire! He'd been smoking on the platform, in contravention of Scottish law, I might add, and stuck the butt in his back pocket, and walked down the carriage with smoke coming out of his arse. Excuse me mate, you're on fire! And he was sober enough to come up with a funny gag - 'I'm just wearing my smoking jacket!' Then his pal, we shall call him bloke 2, lay down across the seats with his big fat hairy stomach poking above the level of the table for all to see. I was ending myself and texting Diane to tell her what was going on. Just as it couldn't get any worse, bloke 2 farted! At Arbroath they both dashed out, relit that cigarette, took one puff and got back on the train. Only in Scotland. Mind Bloke 1 was Irish. Not sure what to make of that.

1 comment:

Bonsaibirder said...

Hi Martin,

I agree with you that it is counterintuitive that IBWO flaps faster than PIWO. But I suppose there is the possibilty that there is some fundamental biological reason why Campephilus woodpeckers fly differently to Dryocopus woodpeckers. I find it very hard to believe that the IBWO is the ONLY Campephilus that flaps fast. So, surely there are videos of other Campephilus species flying which an competent scientist like yourself could have a look at!?