Mean of values in specified grid cells

Discussion created by helenak on May 1, 2012
System  ArcGIS 9.3
Data    a grid map with temperature values for each grid cell
        Five polygon shapefiles for five kinds of butterfly ranges
(species a, b, c, d, e)

I would like to know the temperature mean of the ranges of each species.
For instance, for species a, the steps are as followed.

Step 1. Clip the temperature grid using shapefile of species a
Step 2. Extract the temperature values of each grid cell of the product of step 1
Step 3. Calculate mean of the temperature values

For step 2 and 3, please kindly advise any related python code.
Also, since there is more than one shapefile, please kindly advise if it is possible to batch the whole process (Step 1-3) in python or VBA.

Thanks a lot.