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Re: [Re: Dr. Bakker and Dinosaur intellegence (was: Fwd: ]



owner-dinosaur@usc.edu wrote:
> Larry Dunn wrote:
> > 
> > Reply-To: dannj@alphalink.com.au
> > 
> > >It also depends on what you describe as "intelligent". Crocodiles do
> > >things that seem intelligent in some respects: co-operative hunting
> > >similar to any lion or wolf,
> > 
> > In what way is crocodile piling-on at the water's edge similar to, say,
> > hunting in wolves?
> > 
> > Larry
 
> When migrating herbivore herds need to cross a river, nile crocodiles
> have been observed in what can only be described as cooperative
> hunting. They position themselves strategically and attempt to
> out-flank any lagging individuals. Surrounding the prey also helps to
> block off any avenues of escape, and several animals working together
> are more likely to be able to drag a large animal into deeper water
> where the crocs have an advantage.
> 
> I'm not a croc expert by any means, so if I've got any of this wrong
> then by all means correct me.
> -- 
> ____________________________________________________
>       Dann Pigdon
>       Melbourne, Australia
> 
>       Dinosaur Reconstructions:
>       http://www.geocities.com/capecanaveral/4459/
>       Australian Dinosaurs:
>       http://www.alphalink.com.au/~dannj
>____________________________________________________

Sure "if."

Basically all of what you mentioned is true, but as usual there is more.

Not only has the cooperative hunting been observed in nile crocs taking down 
large terrestrial prey, but it's also been seen in crocs eating large fish 
(Nile Perch come to mind)


The following information can be found in the book Crocodiles and Alligators. 
This book was co-written by many Authors, including Hans Dieter Sues. Copyright 
is 1989, but with croc info you grab what you can. This is a highly informative 
book and I recommend it to anyone who truly loves crocs. I would also be 
interested in any other
good croc books



In Lake St.Lucia, Natal, South Africa, there are annual migrations of shoalfish 
out of and into the lake from the Indian Ocean either to spawn or to feed. 
Species include kob, spotted grunter, but more importantly, striped mullet. 

The annual movement of the mullet shoals is fairly constant, and between 
mid-April and mid-May each year large numbers of crocodiles move down from 
northern open stretches of the lake in response to the fish shoaling. Others 
move up from river systems in the south.

The crocs congregate in an area known as the Narrows. A channel less than 500 
meters in width. Examples of this cooperative feeding/hunting/fishing? are as 
follows:

The crocodiles spread out in a semicircular or line formation
which blocks the passage of the fish. Each crocodile maintains it's place in 
the line and snaps at approaching fish. There is no fighting over prey; shifing 
position and leaving a gap in the ranks would lessen the chances of succesful 
prey capture.

In other Zululand rivers similar behaviour may be seen in summer when rivers 
flood and water spills over into channels leading to natual pans. the 
crocodiles form a barrier where a channel enters the pan, facing the inrushing 
water and snapping up river fishes such as bream and catfish.

But wait there's more.....

On to cooperative feeding. When a croc or group of crocs take down a large 
buffalo or hippo (hey it happens...on occasion) they all gather together to 
feed. Sometimes 30-40 crocs can be seen feeding on the same animal. The record 
so far is 120 sharing the carcass of a hippo in the Luangwa River, Zambia. 
Again the crocs would forma circle and each would take turns grabbing a chunk 
and then moving away to feed on it (BTW this is the exact same thing that has 
been observed in orcas.)

Now when a croc has a piece of a large carcass or a small light weight but 
still to large to swallow carcass, it runs into a problem. It can't rip off a 
chunk, because everytime it spins the carcass spins too. Crocs have two ways of 
dealing with this. One is to gind a branch to lodge it against and then tear 
(that's tool using don't ya know) and two is to enlist the help of another 
croc. This is not two crocs fighting over the same piece, for one is completely 
sedentary and let's the other one do the tearing. One croc helps the other.

It is also noted in that NOVA special on crocs (still by fart the best ever of 
any croc special.) you can see (And Mr. Attenborough will describe it anyway) 
that when tearing at a large carcass, two crocs will go to either side and hold 
the carcass still so as to allwo the others to eat. Each animal takes turns at 
this until they all have had their fill.

So as you can see this is more than just basic instinct. One more thing to note 
is that nile crocs are the most gregarious of crocodiles, which is why most 
cooperative and social behaviour has been done on them (well that and there 
easy to find and observe). 


Crocs aren't the only ectotherms that hunt cooperatively. Oras do it, spunky 
formica do it, some sharks do it, even a rainforest spider does it.

So tell me again about grey matter and a need for endothermy?

Archosaur J

Next time: Pack hunting turtles. Just kidding...I think.


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