NATURE UNBOUNDLESSON 3 – POPULATION CHECKS AND BALANCES

Conservation

Mr. Dieckhoff

THE MISSOURI OTTER

Working with the people at your table, answer the following question: What information do you know about Otters?

Missouri Department of Conservation Video https://www.youtube.com/watch?v=OzG98Fbx7G4 https://www.youtube.com/watch?v=Qve3jLhMYRI

POPULATIONS Boundaries set by

What is the boundary of the Asian Carp?

Population Size - Population Density – Dispersion –

Clumped Uniform Random

MARK-RECAPTURE METHOD

1. Catching a sample of the population and marking the captured individuals with paint, a leg band, an ear tag, etc..

2. After marking, release and allowed to mix back into the population

3. After a period of time, a second sample of individuals is collected from the same place

Lincoln-Petersen Estimate

SAMPLING POPULATIONS

Census – Sample –

Quadrats

Transects

SAMPLING POPULATION EXAMPLES

Black Bears https://www.youtube.com/watch?v=bYoFrPSybiE https://www.youtube.com/watch?v=tJNlstEYHmU

Electrofishing https://www.youtube.com/watch?v=unAdz09rjvg

Ducks https://www.youtube.com/watch?v=I88MJWpcoH4

Otters https://www.youtube.com/watch?v=_VdQnsG8KFQ

POPULATION SIZE CAN GO UP OR DOWN Increased by – Decreased by –

With abundant resources, populations grow quickly Exponential growth –

population increases in proportion to its size (J-shaped curve)

Per Capita Rate of Growth Compare birth and death

rates over time to see if population is increasing or decreasing

LIMITING FACTORS Factors that slow a

population’s growth or prevent it from existing in an area Abiotic – Biotic –

Density-Independent Factors Limiting factors that affect

population regardless of its density

Examples –

Density-Dependent Factors Limiting factors that affect a

population related to its density

Examples –

https://www.youtube.com/watch?v=_e1KA8CpPnA

https://www.youtube.com/watch?v=IrTYdG1s1OA

THE HUNTING DEBATE

Compensatory Mortality Consider a mallard population

in which winter food is a limiting factor. With a large population, there isn’t enough food to go around, and 10,000 ducks die each year of starvation. If hunters kill a percentage of the population, there is more food available to the surviving mallards, and fewer ducks starve. In this example, the number of mallards that die will be the same regardless of whether hunting or starvation is responsible. Thus, if hunters kill 6,000 ducks, 4,000 will die from starvation, and if hunters kill 8,000 ducks, 2,000 will die from starvation.

Additive Mortality If hunters kill 5,000

ducks, it would add to the 10,000 that normally die of starvation. Thus, the population would decrease by 15,000 ducks.

CARRYING CAPACITY

Definition:

CULTURAL CARRYING CAPACITY Number of animals

people will tolerate Issues of urban deer:

https://www.youtube.com/watch?v=AbQQ9cItlOo

Deer birth rates are high Many does produce twins 10-15% produce triplets Higher in northern Missouri

Death rates are falling Fewer predators Hunters take 40-70% of

antlered bucks Hunters take 25% of does What has more affect on

deer populations? harvesting bucks or

does

CONCLUSION

1. Populations – Size, Density, Dispersion2. Mark-Recapture Method3. Sampling Populations4. Population Size Changes5. Limiting Factors6. Hunting – Compensatory vs. Additive7. Carrying Capacity

Cultural Carrying Capacity