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Re: GANGING CROWS & LIZARDS



At 08:23 AM 5/14/99 +1000, Dann Pigdon wrote:
>darren.naish@port.ac.uk wrote:
>> 
>> As similar 'mobbing' behaviours are seen in monitor lizards (there is
>> film of several Komodo monitors bringing down a deer together) and
>> crocs, we can bet that it was very probably present in the
>> behavioural repertories of extinct dinosaurs. As for TRUE pack
>> hunting, a la carnivorans, well, I don't think so.
>
>Why do people tend to stress the difference between "true" pack
>hunting and what I suppose could be called opportunistic group
>hunting? Surely the outcome is the same regardless of the technique -
>a group of animals bring down prey they would otherwise find more
>difficult to catch by themselves.

Yes.  However, the animals for which the term "pack" was invented (wolves,
for example) are more than simply a bunch of conspecifics who band together
to bring down a larger prey item: it is an association of (mostly) kin, the
hunt itself involves a lot of signalling, and *it persists outside the time
of the hunting and feeding event*.  A pack as a structure exists during
"down time".

Why stress the distinctiveness of this condition?  Because people (here on
the net and elsewhere) have done the following:
I) "Hey, there's evidence that _Deinonychus_ hunted in groups".
II) "Hey, that must mean they hunted in packs!"
III) "Hey, that must mean that they had complex signalling during the
encounter!!"
IV) "Hey, if they hunted in packs, then those packs must have been
association of kin, and their must have been a complex social hiearchy, and
they these associations must have persisted outside of the hunting event,
and..."

If we aren't clear that the evidence supports "I" only strongly, we will
continue to propogate the idea that dromaeosaurs were just lions or wolves
wrapped in feathers.

>Again, why differentiate "true" pack hunting? Are us mammal-centric
>creatures so arrogant as to have to separate mammalian behaviours
>from the rest of the animal kingdom?  :)

If there is a difference, it should be pointed out.  Of course, there is
nothing (to my knowledge) PREVENTING birds and other reptiles from forming
semi-permanent coalitions of kin who cooperate during hunting and
non-hunting activities, but it isn't observed (to my knowledge).

By the same token, I wouldn't want to ascribe particular complex avian or
snake or crocodile behaviors to non-mammalian synapsids without some pretty
strong evidence.

Ostrom & Maxwell make a good case (in my opinion) for group hunting in
dromaeosaurids.  It may well be that they had complex signalling in order to
bring down the prey.  It might well be that the members of the group were
all brothers & sisters and parents & uncles & aunts.  It may be that they
had complex social interactions outside of the hunting time (thus answering
the question of how dromaeosaurids groomed themselves: they got someone else
to do it!). However, I'd be hard pressed to find some way of demonstrating
all these later ideas.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661