Migration strategies

[rudy benavides]

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>"3. Classes of Migration
>       Introduction
>       Class I - Emigration, without return, usually by relatively short-
>       lived adults
>       Class II - Emigration and return by the same, relatively short-
>       lived individuals within a season
>       Class III - Emigration to hibernation or aestivation sites and
>       return by the same individuals after imaginal diapause"
>
>The author then points out that these classes grade into each other, and
>breaks Class I into 5 subclasses, and Class III into 3 subclasses (the
>last of which includes the North American Monarch migrations).
>
>       He also defines 'migration' as synonymous with 'adaptive dispersal',
>thus short-circuiting the discussion about dispersal as compared to
>migration.
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Kenelm,
 
It would be interesting to know how he defines dispersal (by classes also?).
  I agree with your comments also.  These are not laws or theories, but
terms to describe phenomena.  As I am learning, authors are going to use
what they wish.  But I admire the efforts of Johnson and Methuen for their
attempts at precision.
 
As a non-entomologist, I have always associated a directional component with
*migration*.  Whereas dispersal to me can occur anywhere within a 360 degree
plane.
 
 
Rudy Benavides
Maryland
 
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