Modeling Predator–Prey Dynamics
275
Choosing a Good Model
I am loath to suggest that any of the models I have reviewed are wrong. Any
model can be a useful construct for understanding, and no model is truly realistic. Models are always abstractions of nature. The issue is choosing a model
that best meets one’s needs. The author of the model is not necessarily the one
who will determine the need for the model. In management applications, careful attention must be paid to identifying the audience and understanding how
the model might be applied.
HOW MUCH DETAIL?
Often the selection of an appropriate model is determined by the extent of
data available. Detailed models might include details of age specificity or, in
the extreme, individually based models can take advantage of high-speed computers to track the fate of each individual in a population through time.
Because radiotelemetry allows us to collect extensive and detailed data on the
movements, behavior, and demography of individuals, building individually
based models is often feasible (DeAngelis and Gross 1992).
Age and sex structure?
Vulnerability of prey is often a function of age, with young and old individuals more vulnerable to predation (Mech 1995). Similarly, prime-age predators
are often more efficient at finding and killing prey, so that both the functional
and numerical responses may be a function of the age of both the predator and
the prey. If differences by age are not large, however, changes to dynamics may
be small, so adding age structure to a model may be difficult to justify given
the difficulty of estimating all of the additional parameters.
Age structure can either stabilize or destabilize the interaction between
predator and prey (Beddington and Free 1976). Populations undergoing predator–prey oscillations are perpetually perturbed out of a stable age distribution, vastly complicating the demography for the populations (Tuljapurkar
1989; Nations and Boyce 1997). Age structure introduces irregularities into
regular oscillations, making the dynamics more complex. Age structure may
also change the period length of oscillations that result from predator–prey
interactions (Oster and Takahashi 1974).
When building a model to anticipate the consequences of wolf predation
275
Choosing a Good Model
I am loath to suggest that any of the models I have reviewed are wrong. Any
model can be a useful construct for understanding, and no model is truly realistic. Models are always abstractions of nature. The issue is choosing a model
that best meets one’s needs. The author of the model is not necessarily the one
who will determine the need for the model. In management applications, careful attention must be paid to identifying the audience and understanding how
the model might be applied.
HOW MUCH DETAIL?
Often the selection of an appropriate model is determined by the extent of
data available. Detailed models might include details of age specificity or, in
the extreme, individually based models can take advantage of high-speed computers to track the fate of each individual in a population through time.
Because radiotelemetry allows us to collect extensive and detailed data on the
movements, behavior, and demography of individuals, building individually
based models is often feasible (DeAngelis and Gross 1992).
Age and sex structure?
Vulnerability of prey is often a function of age, with young and old individuals more vulnerable to predation (Mech 1995). Similarly, prime-age predators
are often more efficient at finding and killing prey, so that both the functional
and numerical responses may be a function of the age of both the predator and
the prey. If differences by age are not large, however, changes to dynamics may
be small, so adding age structure to a model may be difficult to justify given
the difficulty of estimating all of the additional parameters.
Age structure can either stabilize or destabilize the interaction between
predator and prey (Beddington and Free 1976). Populations undergoing predator–prey oscillations are perpetually perturbed out of a stable age distribution, vastly complicating the demography for the populations (Tuljapurkar
1989; Nations and Boyce 1997). Age structure introduces irregularities into
regular oscillations, making the dynamics more complex. Age structure may
also change the period length of oscillations that result from predator–prey
interactions (Oster and Takahashi 1974).
When building a model to anticipate the consequences of wolf predation