In Harvest Management what two court decisions were made regarding wildlife?
1896- States Control Manner of Take
1910-States own resident wildlife
What Treaty allows federal control of migratory species?
Migratory Bird Treaty Act
What gives us a reason (rationale) for harvest?
There is a biological surplus available for harvest without impact to breeding population
Additive vs. Compensatory Mortality
-What is the defintion of both of these?
Additive Mortality-each animal killed by hunter is an additional death that adds to the natural mortality resulting in total mortality being greater than if hunting did not occur.
Compensatory Mortality- when animals have a relatively stable annual mortality, regardless of which decimating factor may be acting on the population, removal of hunting would equal an increase of mortality from predation or disease
What is the Law of Diminishing Returns?
A concept were past a certain point of time, hunting is largely unrewarding-(furbearing season)
What is defintion for Harvestable Surplus?
Most animals produce more young than necessary to maintain the population, the extra number can be removed by hunting
What is Doomed Surplus?
Number of animals produced exceed the capacity of its habitat
What is Opening Day Phenomenon?
When most mortality is thought to occur
What are the 3 components of harvest management?
1. Inventory of population
2. Identification of population and harvest goals
3. Development of regulations that allow goals to be met
What are 2 harvest strategies?
Heavily Hunted Species- frequent changes in response to new information
Lightly Hunted Species- Regulaions often remain unchanged for years
What are 2 methods to adjust harvest?
1. Inventories-bases harvest on abundance
2. Harvest Surveys
What are the 4 key components for Adaptive Harvest Management?
1. Set of models describing population responses to harvest and environmental variation
2. A measure of reliability for each model
3. A limited set of regulatory alternatives that differ in excpected harvest rates (seasons, bag limit)
4. objective funtion- a mathematical description of the objectives of harvest management
What is the 4 step process for setting regulation annually (Adaptive Harvest Management)
1. Optimal regulatory alternative is identified based on breeding populations and habitat conditions
2. Once a regulatory decision is made, model-specific predictions for breeding population size is made
3. Model weights are updated if monitoring data are available to compare with observed population size
4. New model weights start another iteration of this process
-Overtime iteration process of updating model weights and optimizing regulatory choices should identify which model is the best predictor of change in population size
Give an example of an overabundant species and explain what is being done?
-Snow and Ross's Geese
-Conservation Order-enacted to reduce populations to sustainable level
-Increase bag and seasong length, expanded methods of take
-Done to reduce environmental and economic damage
What is Maximum Sustainable Yield (MSY)?
Maximum number of individuals that can be harvested
What is population viability?
A populations capability of normal growth and development
List 3 ways that the loss of genetic variation affects population viability
1. Decreased population growth
2. Incresed extinction probability
3. Reduced population productivity
What causes the loss of genetic variation in a population? What does this to to the population?
1. Fragmentation/isolation leading to small populations
2. Re-establishment using too few individuals
-Leads to inbreeding and loss of alleles
-Cause population to be more vulnerable to environmental change (less ability to adapt)
What is the solutions to population viability regarding genetics? (3)
1. Maintain large effective population sizes
2. No agreement on a standard minimum
3. Most studies report a minimum effective size
What is the factor decide a small population?
-Life history characteristics matter
-Small population means a restricted range species
-Scale population size necessary to retain 95% of the heterozygosity for 100 years
What is makes a large population?
-Species with highly varicance in population growth rate
When was the 50-500 rule proposed? What does the 50 and the 500 mean?
-A historical rule proposed in 1980
-50 - Proposed effective population size(Ne) of 50 individuals (about 1/5 to 1/3 of total population size) to protect against short-term loss of fitness
-500 - Proposed minimum population size of 500 to protect against long-term maintenance of genetic variation
What orginizations classify small populations?
-Natural Heritage Program (G1 to G5 rankings)
-U.S. Endangered Species Act (1973)
What factors affect persistence of small populations?
-Deterministic - the outcome is predictable (habitat losss or overharvest)
-Stochastic - Random effects
Demographic-variation in birth and death rates Environmental-random changes in vital rates across individuals
Genetic- random loss of alleles
What is a Extinction Vortex?
Predicts how deterministic and stochastic factors interact to produce a decline in a small population
What is the Population Viability Analysis?
-Its a subset of a vaibility assessment
-Application of data and models to predict the likelyhood a population will persist for a specified time into the future
-includes the concept of Minimum Viable population size(MVP)
What are the 3 characteristics of Population Viability Analysis?
2. Time (short-term and long-term projections)
3. Likelihood (expressed as a probability of extinction over a specified time interval)
What does Population Viability Analysis provide when managing small populations?
-How to increase the size of a small population
-How to decrease risk of extinction
What are the 5 key components when managing small populations with Population Viablity Analysis?
1. Improve recruitment
2. Improve survival
3. Population Augmentation
4. Habitat Protection
What are the 3 Population Viablity Limitations?
-They often depend on incomplete knowledge(data)
-They do not predict the fate of a species (focus on factors)
-It's not practical or possible to conduct a PVA for most species
The ability of an organism to survive and reproduce depends on what? What other factors are reflected from this?
-Resources available to it (habitat)
-Habitat Resources reflect species richness
-Habitat quality reflects density
What should be measured in a habitat evaluation?
-What is the goal of the study
-Study focus (species, population)
-Species interrelationship with the environment
-Time of day or season when habitat is used
-Influences of habitat features at different spatial scales
What 2 classifications types are measured in habitat evaluataion?
-Macro Features - size, distance to water edge, vegetation
-Micro Features - plant species compisition, water chemistry
What does Low and High Ix mean? Same for Jx?
-Low Ix means similar habitats while High Ix means there are many habitats
-Low Jx means there are few similar habitats in close proximity while a high Jx means there are many in proximity
What is a Habitat Suitability Index?
-Study area habitat conditions/optimal habitat conditions
What are Suitability Index Models and how are they made?
-Developed by USFWS
- Habitat suitability calulated from physical and biological attributes
- Habitat suitability is proportional to K
- Generally linear models with habitat variables for multiple species
What are the 4 main types of Habitat Suitability Index Models?
1. Habitat-capacity models
2. Pattern-recognition models
3. Life-form models
4. Guild Models
What vegetation components are important to wildlife? (6)
-Vertical/ horizontal spatial distribution
-Temporal variation in structure
-Overall stand structure
-Landscape structure (surrounding environment)
What are the primary vegetation sampling techniques? (4)
1. Frequency of occurrence
4. Biomass or standing crop
For vegetation sampling techniques what is frequency of occurrence? What is it useful for?
-The proportion of sample units in which a species occurs
Example- 100 plots, 20 Oaks, frequency of occurrence is 20/100=20%
-Distribution within a community
-Monitoring change in a community
What does a frequency measure suggest about a plant's distributional pattern?
-Low frequency (<15%) = aggregated (several types)
-High frequency (>95%) = uniform (all the same)
Frequency will vary with size and shape of the sample unit over time and among communities, size and shape are a function of plant types being sampled, what are the 4 types of plants?
1. Herbaceous vegetation (1-2 m2)
2. Tall herbs and low shrubs (4 m2)
3. Tall shrubs and low trees (10 m2)
4. Trees (100 m2)
Regarding vegetation sampling techniques what is density? Where are the results obtained? What information does density not provide?
-Total number of plants per unit area
-Results obtained from different sampling methods are directly comparable
-Does not provide information on how plants in a community are distributed
What two ways can Density be measured?
1. Quadrat methods (made with material with fixed boundary)
-must consider plant distribution, size and shape of quadrat, sample size needed
2. Plotless methods (ocular methods)
In vegetation sampling techniques what is biomass? What who vegetations are included? What can it be divided into?
-Plant composition based on dry weight-best indicator of species importance in a community
-Includes live and dead vegetation
-Can be divided into total biomass and biomass of edible components
How is biomass measured when sampling vegetation?
-Clip all vegetation in a sample plot and weigh it before and after drying
-Clip at ground level
-Sometimes only edible portion of plants are clipped
What are the two different biomasses that are measured? What is another type of measurement used that requires extensive training?
1. Total biomass (wet or dry)
2. Biomass per unit area
Canopy cover (Cover) is viewed from what direction and how is it expressed?
- Viewed from vertical
-Expressed as % cover
Visual obstruction is viewed in what direction and expressed as what?
-Viewed from horizontal
-Expressed as % obstruction or numerical score
What is the definiton of Cover?
-The percent of the ground surface covered by vegetation or other material
What are the reasons for Cover being important to communities? (5)
1. Very important functionally
2. Criterion for relative community dominance
3. Intercepts ligh and precipitation
4. Impacts soil temperature
5. Restoration ecology, community ecology, competition
What are the 4 types of Cover?
-Basal Cover - measure only the portion of plant that extends into the soil
-Foliar Cover - Measure vertical projection of the exposed leaf cover (a shadow)
-Canopy Cover - An estimate of the plants are of influence (includes roots)
-Ground Cover - The cover of the soil surface with plants, rocks, litter
What is Cover strongly related to? What 2 things is it useful for characterizing?