32

To reflect the real system, the model also must maintain

the bird population under natural conditions. The first

question that arises is what structural conditions inherent

in the natural system must be included in the model to

insure a simulation of the long-term survival of the Wood

Stork population.

 The second question of consequence is how have man's

changes in the structure of the system affected its ability

to maintain wading birds; or will the Wood Stork be

eliminated from south Florida under changed conditions? If

the Wood Stork is disappearing in south Florida, it may be

a number of years before the fact is obvious, and it may

then be too late to do anything about it. Model

simulations are able to provide clues to the future. They

allow the exploration of questions of both theoretical and

practical importance.



 Population Biology of Wood Storks

 Population size is ultimately controlled by energy,

usually food energy. Annual variation in population size

has been related to annual variation in the energy base of

a number of bird species, including the Great Tit (Perrins,

1965; Krebs, 1970) and the Tawny Owl (Southern, 1970).

Energetic influences limit bird populations by affecting

number of breeding pairs, clutch size, hatching success,

nestling survival, and mortality rates in the first (or