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Re: flocking



At 03:39 PM 5/17/99 -0400, Andrea Kirk wrote:

>All of this talk of pack hunting and group social behaviors made me think
>of another common group behavior.  I'm sure most people have seen gigantic
>flocks of starlings or blackbirds that, while flying, may all suddenly
>wheel and turn in unison.  What allows them to communicate this sort of
>action to one another?  And in the world of pure speculation, is it
>possible birds have inherited this trait from the theropods?  Or is it
>something that has evolved much later? I'm not sure what other birds
>participate in this sort of behavior...

Well, I don't know that this actually addresses the actual mechanism of
these group flock turns, but such patterns can be fairly accurately
*simulated* on computers with just a couple of basic rules.  I can't
remember them all, but they are something like: each flock member tries to
get towards the center of the flock; each flock member tries to maintain a
minimum distance from other members; each flock member tries to avoid
hitting any obstacle (the last is a natural, but you have to program that
into the computer or you get messy results... :-).

In any case, with just a few simple rules, people have done some very good
computer simulations of bird and bat flock behavior (and fish schooling),
some of which have made their way into movies.

In any case, if birds and others are actually following these algorithms, if
just one or a few members turn for whatever reason, that turn will cascade
throughout the flock/school relatively easily and swiftly.

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