2.3 Case Studies
During the period of wolf recovery in the 1990s, we worked with decision
makers and biologists to define and address five wolf management questions, in this order:
1. What conditions support or hinder the persistence of disjunct wolf populations in human-dominated landscapes (e.g., newly colonized habitats
in Wisconsin)?
2. What are the cumulative effects of regional environmental conditions
and human-caused mortality on wolf population size in a small park
(e.g., Voyageurs National Park)?
3. How much disturbance does it take to cause reductions in a small wolf
population?
4. Is vasectomy a practical alternative for controlling or reducing the size
of a disjunct wolf population?
5. What wolf removal strategies are most effective and efficient for reducing wolf depredation on livestock?
Our management questions involved predicting the impacts of humancaused mortality, regional environmental conditions, and disturbance on
the persistence of wolf populations. In addition, the management questions
involved predicting the relative performance of different strategies for
controlling wolf population size and depredation. We decided not to model
these environmental processes and control strategies directly. Rather, we
made a demographic model of wolf population dynamics and made assumptions about how these environmental processes and control strategies
affected the birth, survival, and dispersal of wolves. Then, we used
the model to investigate the population impacts of changes in these demographic parameters. Finally, we interpreted the model results as inferences
of the population impacts of the environmental processes and control
strategies.
We constructed the wolf population model to represent key elements of
wolf demography and social organization. Because wolves live in packs and
defend territories, we decided to represent a wolf population as a collection of packs and to model the demography of each pack. Within a pack,
only one female breeds each year, and mortality rates are age dependent.
Furthermore, we were interested in the population impacts of human activities that affected breeding.Thus, we decided to use a stage-structured model
that kept track of the age, sex, and breeding status of wolves in each pack.
Juvenile and adult wolves disperse from natal packs in search of mates and
territories. Because of the great variation in dispersal behavior, we decided
to use a random dispersal process and did not represent territories as specific shapes on an actual landscape.
2. Modeling for Endangered-Species Recovery
27
During the period of wolf recovery in the 1990s, we worked with decision
makers and biologists to define and address five wolf management questions, in this order:
1. What conditions support or hinder the persistence of disjunct wolf populations in human-dominated landscapes (e.g., newly colonized habitats
in Wisconsin)?
2. What are the cumulative effects of regional environmental conditions
and human-caused mortality on wolf population size in a small park
(e.g., Voyageurs National Park)?
3. How much disturbance does it take to cause reductions in a small wolf
population?
4. Is vasectomy a practical alternative for controlling or reducing the size
of a disjunct wolf population?
5. What wolf removal strategies are most effective and efficient for reducing wolf depredation on livestock?
Our management questions involved predicting the impacts of humancaused mortality, regional environmental conditions, and disturbance on
the persistence of wolf populations. In addition, the management questions
involved predicting the relative performance of different strategies for
controlling wolf population size and depredation. We decided not to model
these environmental processes and control strategies directly. Rather, we
made a demographic model of wolf population dynamics and made assumptions about how these environmental processes and control strategies
affected the birth, survival, and dispersal of wolves. Then, we used
the model to investigate the population impacts of changes in these demographic parameters. Finally, we interpreted the model results as inferences
of the population impacts of the environmental processes and control
strategies.
We constructed the wolf population model to represent key elements of
wolf demography and social organization. Because wolves live in packs and
defend territories, we decided to represent a wolf population as a collection of packs and to model the demography of each pack. Within a pack,
only one female breeds each year, and mortality rates are age dependent.
Furthermore, we were interested in the population impacts of human activities that affected breeding.Thus, we decided to use a stage-structured model
that kept track of the age, sex, and breeding status of wolves in each pack.
Juvenile and adult wolves disperse from natal packs in search of mates and
territories. Because of the great variation in dispersal behavior, we decided
to use a random dispersal process and did not represent territories as specific shapes on an actual landscape.
2. Modeling for Endangered-Species Recovery
27