326

 In Figure 81 a prey-predator model suggests how the

process of concentrating prey may increase energy value to

the predator. In the diagram, the flow of food to the

predator is equal to k X Y, where X is the biomass density

of prey and Y is the predator. If X = g/sq-m and the

number of square meters is reduced from 1 to 0.01, then

g/sq-m, or X, is increased by a factor of 100. Ten grams

of fish in 1 sq-m would have an energy value 100 times

greater than the same amount of fish in 100 sq-m, according

to thi-s equation. The increase in energy value of prey to

predator according to the model is proportional to the

square of radius of dispersed habitat divided by the radius

of concentrated habitat. At the 1974 maximum fish density

in Corkscrew marsh (0.42 g/sq-m), one Wood Stork would have

to harvest the fish occupying 356 sq-m of marsh in order to

feed itself and one growing nestling on an average day of

the nesting season. By contrast, feeding in Mud Lake Pond

during the dry down when fish densities exceeded 4.2 g/sq-

m, a Wood Stork could catch a day's supply of food from 36

sq-m.

 Differences in fledgling production in Model II under

different regimes of oscillation of water area exhibited by

the simulations in Figure 76 demonstrate the effect on the

Wood Stork population of increased energy flow resulting

from concentration: higher production from the same amount

of water area.