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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
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What are the causes of diseases?
- - Instrinsic flow (hereditary or congenital diseases)
- - Deficiency diseases
- - Exogenous poisons
- - Living organisms
- - Viruses
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Deficiency diseases
- 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
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Exogenous poisons
- cause local injury to tissues
- destruction of epithelial cells in the kidney or liver after absorption
- upset metabolic and functional activities
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Living organism diseases
- Metazoan parasites
- Pathogenic protozoa
- Bacteria
- Fungi
- Viruses (hear about the most)
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What are the implications of wildlife diseases on human health?
- Lyme Disease
- The Plague
- Rabies
- Anthrax
- Chronic wasting disease
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Lyme Disease (what is the first host?)
- Persistant
- 1st host is small mammals
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The Plague (reservoir? Change of getting to humans)
- Reservoir in small mammals (fleas)
- Small chance to humans
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How is Chronic Wasting Disease transmitted?
Contact to contact
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Aldo Leopold
Big advocate of predator control
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Predator
An animal that survives by killing and eating other animals
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What are the two modes of protection of prey?
- Hiding (camoflage)
- Defense (prey fight back)
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Where is the energy spent for predators?
- Large investment of time and effort per prey item
- Make kills very infrequently
- (lots of energy used)
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Evolutionary significance of prey and predators?
A steady strengthening of the genetic heritage of the survivors within a prey population
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Lotka and Volterra (what controls prey population?)
- There is a lag for predators
- Resources/habitat of prey control prey population
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Huffaker
- Used organs and herbivore mites
- Population fluctuated widely
- When predators introduced caused extinction
- Complex environment
- Prey able to disperse ahead of predators
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Errington
- 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
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What are the two types of predator responses to prey density/distribution?
- Functional Response
- Numerical Response
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Functional Response
- Predators to shift their diets toward an abundant of prey
- Can occur without predator increase and takes more time
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Numerical Response
- The numbers of predators increase with an increase in the density of the prey population
- Harder to measure than functional response
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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
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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)
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When understanding predation, what must you know about the characteristics of the predators?
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Buffer species
Secondary prey species which absorbs some predatory pressure when the primary prey numbers are low
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Facultative predators
Consume other prey that allows a higher predator-prey ratio than if primary prey were the sole or primary food
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What are the factors that effect predation?
- Complicated because the impact of predators on prey is complex
- Limiting factors
- Regulating factors
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Limiting factors on predation
Both density-dependent and density-independent factors that reduce the rate of population growth
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Regulating factors on predation
Only density-dependent factors are a subset of limiting factors
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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
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When did the federal government become involved in predator control? Why?
- 1855
- Pastoral communities have less problem with predators (they actually watched their cows)
- Tried to deal with plague bearing rodents
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National Animal Damage Control Act
- 1931
- Every state follows this act
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Leopold Report
- 1963
- Evaluated idea of predator control
- Lethal control not most important option (yet still an option)
- When lethal control used, must be targeted
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Cain Report
- 1972
- Environmental awareness became more prevalent
- Era of rebellion, photojournalists taking photos
- Arial gunning
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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
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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
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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
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