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"Life of Birds"



Attenborough’s "Life of Birds"

Early on, lots of different kinds of birds queuing up to catch dragonflies – even a big fat hornbill flopped off a tree and grabbed one out of the air in its beak with no difficulty at all. IMO, Archaeopteryx clearly could have caught them. I found this film so beguiling that I am even willing to believe it could have swiped at them with its wings (if it wanted). A hit with the claws would have been best, though a hit with the feathers would knock it out of the air. After all, the old rolled-up newspaper, and the modern-day video cassette envelope work well enough. Of course, this would not be a convincing enough reason to develop feathers.

Some really very convincing shots of flying rhamphorhynchids. But although the film went a long way towards giving the flexibility and moving curvatures necessary for a realistic image (for pterosaurs, if not Archae), it wasn’t quite there. The moas bodies went up and down too much as they walked. Plenty of sauropods peering over the clifftops where the pterosaurs nested.

It was nice to see the Solnhofen and Messell sites in the flesh. The first Solnhofen feather was shown, described correctly as asymmetric and compared to a modern feather – also said to be asymmetric, though it clearly wasn’t. Of course modern flying birds have many fairly symmetrical wing feathers, and they only indicate flightlessness in fossils when they clearly come from the right part of the wing.

Feathers were described as being simply made of the same substance (keratin) as reptilian scales. OK, but I can’t help feeling we’ve all now (on the list) got the impression that feathers are just different shaped scales, wheras a few months ago, I’m sure we concluded there was some notable difference.

Interestingly, the film claimed that reptilian scales must have been very hot, and feathers could be fluffed up for cooling during the day (and keeping warm at night almost as an afterthought). Temperature control was thus advocated as their main initial purpose. Then, on being shown footage of an Aussie lizard with a truly massive neck frill, running along on its hind legs, I was amazed to find myself being very nearly convinced (just for a moment) that enough lift could be generated to . . . have some effect. Of course initially, little hops off the ground would be of hardly any use against predators, since you have to land again very soon. (Flying fish escape predators through ‘flying’, but this is because they become much more difficult to see once they leave the water, and they are (I believe) able to change direction in mid air. What’s more, adaptations for speed through the water makes them preadapted for minimising drag through the air. All this makes short flights for them much more effective for escaping than for a leaping lizard.) Also, good runners need to foster an intimate relationship with the ground. Sprinters try to keep in contact with it as much as possible, and pressure as well as time is important here. More obviously, rapid changes of direction need lots of ground contact – unless of course you are able to profit more from your contact with the air than you lose through less contact with the ground. I’ve never seen, and this film didn’t show it, any flightless bird using its feathers to help in its running. To be fair however, this was the most convincing presentation of ‘Ground Up’ I have ever seen.

Presented with equal weighting though was ‘Trees Down’ – tellingly, they were able to demonstrate a real creature (lizard) gliding. David Attenborough obviously hadn’t read the Feb ’98 Sci Am, since he said "Archaeopteryx was certainly well equipped for climbing". Better go to Prof Padian for a few lessons on interpreting animal structural adaptations! Totally convincing views of hoatzin chicks demonstrating climbing with wing claws (though I think I’ve seen that footage from an earlier film). Call me dozy, but until watching this program I had never been really happy about Archae using claws at that funny angle. Now I realise they only look odd because most other clawed animals are seldom seen pointing their ‘hands’ out sideways. Angle the arms forward at the elbows, and the claws are just right for pulling with. When flying, the claws moved sideways through the air, with the tips pointing down. Of course. I wonder if it hinged its primary feathers back while climbing up trees.

Nice to see a seriama. Much like a bustard; perhaps a tad spindlier.

I learned an important lesson here. Clearly, although Attenborough may not know all the details about the fauna of the Messell deposits, he managed to steer his way charmingly through a (fairly superficial) account of possible stages in the evolution of flight, with enough wisdom to avoid making any huge annoying mistakes. I don’t remember that being done before by anyone not espousing my theory. It IS possible!

Shots of ostrich feet – I didn’t realise O’s are well on the way to becoming single toed. The film said they could do 40mph, but I believe they can do 60mph if you chase them in a jeep. Why should they be able to? Prey animals may well experience significant pressure to exceed their potential predators’ top speed by a wide margin - so long as the predators hunt in packs. Ostriches can kill lions, but I bet lions kill more ostriches. However, a cheetah was shown casting meaningful glances at a flounce of ostriches. The film said the cheetah probably wouldn’t bother chasing an ostrich since there wasn’t as much meat on one as on a mammal of a comparable size. Hmmm!! And double Hmmm!!

Shots of flightless cormorants. I don’t see why they abandoned their wings for swimming – don’t flying cormorants flap under water? However flightless comorants still hold their wings out to dry. Odd. And most definitely not elegant, as the film claimed, even underwater.

The sea … the sand … the stars … the Attenborough … the kiwi …the kiwi’s silky whiskers glinting in the starlight …. "Its feathers are just filaments, so that it almost looks as though it was covered in coarse fur". Damn. I knew I shouldn’t have walked past the NHM last week. Are we looking at a bird that has only been flightless for 60ish mys? I hope so, because I’m back to thinking New Zealand was wiped clean of birds and mammals after isolation. All the birds flew in. Frogs and lizards must have rafted. It might not have been far then; it’s only 1500 miles now. Must get a list of Jamaican animals (including invertebrates) – J has never been in contact with any mainland (it is thought) – and has only one ‘indigenous’ non-bat mammal. I wonder if anyone knows what moas’ feathers were like.

The giant eagle was played by a Harris Hawk – I bought it, though the beak would have been proportionally much heavier. The Kakapo (flightless parrot) inflated itself like a beachball before making funny little hooting noises. I wonder how many maniraptorans did that? Segnos, I wouldn’t be surprised.

 

JJ

Hold onto your hat, Texas!