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Why should wildlife managers study wildlife diseases?
- - may serve as reservoirs or as vectors for pathogens that ultimately affect each other or humans
- - density of wildlife populations
- - diseases may cause serious losses to already small populations
- - diseases are a part of the whole spectrum of issues facing wildlife managers
What are the causes of diseases?
- - Instrinsic flow (hereditary or congenital diseases)
- - Deficiency diseases
- - Exogenous poisons
- - Living organisms
- - Viruses
- inadeqaute nutrients in the diet
- poor quality diet
- interference with intake, absorption of nutrients, and storage and use of nutrients
- increased excretion
- increased dietary requirements associated with pregnancy or lactation
- inhibition of nutrients by inhibitors
- cause local injury to tissues
- destruction of epithelial cells in the kidney or liver after absorption
- upset metabolic and functional activities
Living organism diseases
- Metazoan parasites
- Pathogenic protozoa
- Viruses (hear about the most)
What are the implications of wildlife diseases on human health?
- Lyme Disease
- The Plague
- Chronic wasting disease
Lyme Disease (what is the first host?)
- 1st host is small mammals
The Plague (reservoir? Change of getting to humans)
- Reservoir in small mammals (fleas)
- Small chance to humans
How is Chronic Wasting Disease transmitted?
Contact to contact
Big advocate of predator control
An animal that survives by killing and eating other animals
What are the two modes of protection of prey?
- Hiding (camoflage)
- Defense (prey fight back)
Where is the energy spent for predators?
- Large investment of time and effort per prey item
- Make kills very infrequently
- (lots of energy used)
Evolutionary significance of prey and predators?
A steady strengthening of the genetic heritage of the survivors within a prey population
Lotka and Volterra (what controls prey population?)
- There is a lag for predators
- Resources/habitat of prey control prey population
- Used organs and herbivore mites
- Population fluctuated widely
- When predators introduced caused extinction
- Complex environment
- Prey able to disperse ahead of predators
- Social interactions within muskrat populations
- Mink predator = high when muskrat population = high
- “walking corpses” (will eventually die of something else)
- Social interactions in crowded populations = limit prey (more than predation)
- Total effect of predation cannot be found by counting number of animals killed by prey
- Mortality factors such as disease, starvation and predations frequently compensatory rather than additive
What are the two types of predator responses to prey density/distribution?
- Functional Response
- Numerical Response
- Predators to shift their diets toward an abundant of prey
- Can occur without predator increase and takes more time
- The numbers of predators increase with an increase in the density of the prey population
- Harder to measure than functional response
To understand predation you must know…
- Density of prey population
- Density of the predator population
- Characteristics of the prey (ex avoid getting eaten)
- Characteristics of the predator
- Abundance of buffer species or alternative food for the predator
When understanding predation, what must you know about the characteristics of the prey?
- (ex. Avoid getting eaten)
- Migration beyond the range of their main predator
- Shift habitats to areas with poorer nutrition
- Reduce risk by grouping together (very effective)
- Isolation of female when they give birth
- Birth Synchrony (everyone has young at the same time so the predator is full early)
When understanding predation, what must you know about the characteristics of the predators?
Secondary prey species which absorbs some predatory pressure when the primary prey numbers are low
Consume other prey that allows a higher predator-prey ratio than if primary prey were the sole or primary food
What are the factors that effect predation?
- Complicated because the impact of predators on prey is complex
- Limiting factors
- Regulating factors
Limiting factors on predation
Both density-dependent and density-independent factors that reduce the rate of population growth
Regulating factors on predation
Only density-dependent factors are a subset of limiting factors
What are the models that examine the role of predation in the population dynamic of ungulates (aka predatory-prey relationships)
- Recurrent fluctuation hypothesis
- Low Density Equilibria
- Multiple Equilibria Hypothesis
- Stable limit cycle hypothesis
When did the federal government become involved in predator control? Why?
- Pastoral communities have less problem with predators (they actually watched their cows)
- Tried to deal with plague bearing rodents
National Animal Damage Control Act
- Every state follows this act
- Evaluated idea of predator control
- Lethal control not most important option (yet still an option)
- When lethal control used, must be targeted
- Environmental awareness became more prevalent
- Era of rebellion, photojournalists taking photos
- Arial gunning
What are some common situations where predator control is warranted?
- Protection of T and E species
- Reintroduction of T and E species
- Protection of domestic livestock (predators will go into barns)
- Increase game numbers
When can predator control be successful?
- To increase prey populations (when the prey population is below ecological niche)
- If it has been correctly identified as the limiting factor
- Control should be focused on a scale small enough to obtain results
When should predator control be implemented?
- It should occur just before predator or prey reproduction
- Control efforts need to be severe enough to yield results