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The Harris Hawks in that program (see John C.
McLoughlin in "Nomen" - 25.3.98) sometimes hunted in groups larger
than two I think - maybe four or five sometimes, though it was stressed that
this was unusual in modern birds almost to the point of uniqueness. There
were two different roles at least though I'm not sure if there were any more
than that.
The Hobby falcon hunts swifts in pairs, and
there was until recently a bird, I think from NZ which filled the woodpecker
niche by having one sex (M. I think) with a heavy chisel-like beak for opening
up the wood, and the other with a completely different tweezery beak for picking
out the grubs. Extinct of course, and it serves them right for
discriminating against singles!
Pelecans have two modes of hunting - dive-bombing like gannets
(and boobies?), and paddling along in a tight U-shaped formation with the open
end advancing, and simultaneously dipping their beaks in together. Some
individuals, I believe, hunt one way or the other depending on
circumstances
Could dino's have matched mammals' complexity in
their hunting cooperation? Do any non-primate or even non-human mammals
have more than two roles (ie the flusher and the ambusher)? Harris Hawks
are well known for tackling very large prey, and many birds can even fly with a
victim much heavier than themselves. Presumably they have little need for
help in dispatching large prey, though they may do for prey which keeps darting
out the back of a thorn bush into another one. A question arises - how
would a pack of hawks kill an animal the size of a medium to large
deer?
They have a problem - no teeth, and no slashing claws.
These are weapons for dealing with very much larger prey in packs. Notice
that cats specialise in killing with penetrating bites (and climbing) and
usually don't hunt in packs. Lions are the big exception, though cheetahs
and I suppose a few others cooperate sometimes. Dogs have different jaws
suitable for tearing, and they more usually do hunt in packs (and avoid
climbing).
If you can rip enough shreds off your prey, eventually you
will bring it down. Cumulative penetrations I feel would be less
effective, and the best support for this might be that very few animals do it
these days. (You might mention sabrecats as a counter; fair enough.
Venomous animals usually only make a small number of bites, and don't usually
hunt in packs. Well, snakes can't share, can they? Ants however do
display the ability to hunt in packs, but with very little brain
power.)
I think many theropods hunted in packs because
enough birds do to show that bird brains are capable of it (though admittedly
many pre-maniraptorans weren't even bird-brained), and the fact that most birds
don't is accounted for by the fact that they don't need help killing large prey,
and their weapons are unsuitable for pack hunting. (Presumably the reason
so many birds of prey have penetrating rather than slashing claws is that they
hit their prey at high speed, pinning it to the ground, a scenario likely to
favour penetrating claw design. [That comment will cause problems for me
later!]. Where prey is caught in the air, without anything to press
against, a slash is likely simply to knock the prey away from the predator, so
grabbing hold would be better. Besides, birds with feet suitable for use
as weapons tend to have the ability to grasp branches - a similar action to the
squeeze-stab. Peregrine-type one-hit mortal blow behaviour is so
specialised that the suggestion that it has evolved lately is likely to be true,
and it is unlikely to have been a common habit for other birds.) I think
teeth were originally lost to lose weight; you lose not just the teeth but also
the sockets and everything else to support them, which are many times
heavier.
I don't think simple, one-role cooperative hunting requires
special brain power, and theropods had teeth perfectly suited for the pack
mode. What exactly do Komodo Dragons do? They can't aways make a
slash and wait for septicaemia to set in! Do they hunt in
packs?
John V Jackson
"Please don't give a hyaena as a pet this
Christmas!"
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