Friday, 30 April 2010

Who's a clever boy then?

Recently there was a paper published on an obscure species of crow on a small island in the Pacific, and it made the BBC news. The reason was the extraordinary intelligence of the crow. Not only do they use tools in the wild to find food, but they actually make them, whittling wood and tearing leaves. They are the only species of bird known to do this, and better yet, they are problem solvers. Faced with a puzzle where they had to pull up a string with a small stick on the end, use this to get a larger stick and in turn use this to obtain food, one bird (called Sam) spent 110 seconds looking at, then solved the puzzle straight of the bat. Others were not so bright, but they got their in the end.

Of course the corvids - crows, ravens, jackdaws and magpies - have been renowned for their intelligence from the days of Aesop. Stories abound of their cunning and intellect, and this is starting to be borne out by science. For example, the magpie is the only non-primate known to recognize itself in a mirror, showing at least some self-awareness.

So why aren't birds masters of the universe? One limiting factor is brain size, although birds seem to use a different part of the brain for thinking, size is stiil linked to intelligence. Birds are limited by the necessity to fly, and brains are both heavy and hugely demanding of energy. The human brain uses 25% of the bodies energy, though it's only 2% of the weight. In order to fly many bats have had to evolve smaller brains, not larger.

Some birds of course have given up flight, such as the ostrich, but they are not obvious candidates for high intelligence.


So, where does this leaves the Mata Atlantica?

Well there are not many crows here, but there are parrots, and they are pretty bright. African grey parrots have a high brain to body ratio, and can, for example, learn the meaning of quite a few words and count up to six. The Kea, from New Zealand, is extremely adaptable and opportunistic, with a very complicated soical system, and it too can solve simple problems, though not as well as the crows.

Brazilian parrots and parakeets are certainly social and (very!) vocal. The earliest Portuguese settlers amused themselves but teaching captive parrots to speak Portuguese, and the best sent back to Lisbon, leading to a popular local saying " the well-spoken parrot goes to Portugal". As yet there are few studies of local species, but the Hyacinth macaw, the largest flying parrot in the world, seems to pretty clever.

However, the limitations of flight still apply. But... in the past there were birds in the Mata Atlantica that were flightless, and had HUGE heads, the terror birds. One for example had a skull about the same size and length as that of a horse, so were they especially bright? Well, a big skull doesn't necessarily mean a big brain, in this case over half was taken up with an enormous, crushing beak, which also required muscle attachments, and two large eye sockets. So, it was big and mean, but maybe, just maybe, it was a little smart as well.


Sarah Stephen said...

One of the more famous research groups in Tinbergen Bldg.

For feeding the squirrels, we improvised a basket tied to the mahogany. Unfortunately, the crows were eager to partake in this daily feast as well, and thus we included a straw cover through which only the squirrels could squeeze through. Little surprise that the crows soon dismantled it!

I'd like to know more about this terror bird!

Ruth Stephen said...

'a big skull doesn't necessarily mean a big brain'. I love this quote!

And yes crows, I dsiliked them as a child but I do have some respect now.

Anonymous said...

Inteligent, I dont know . . . "Funny"
they are!

Steven said...

Hence the expression "bird brain"

The big skull/small brain is a very good description of Homer Simpson.