1. Estimating Population Size

2. Journal Entry
What types of populations does random sampling work well with?
What are the drawbacks of using random sampling?
How would you sample a mobile population?

3. How do we monitor moving populations?
Look at the following video –
Wildebeest Migration

4. Understanding Populations - Big Ideas
Population sizes change according to changes in the environment.
The size and growth rate of human population has changed drastically over the last 200 years. Those changes have led to profound changes to almost every place on Earth.

5. How Populations Change in Size
GOALS
Describe the 3 main properties of a population
Use two methods to estimate population size
Explain how behavior influences population dsitribution

6. The Decline of the Passenger Pigeon
How does a species go from having billions to extinct in just one century…The Passenger Pigeon Story.
Extinct in the wild since 1900 and last died in the Cincinnati Zoo 1914.

7. Review: What is a population?
Population: all the members of the same species that live in the same place at the same time
Field mice living in a corn field, wolves in Yellowstone National Park, blacks bears in northern New Jersey

8. Population Size Why care about the size of the population?
How can scientists estimate the population (say of Elephant Seals on a beach in CA)?

9. Population Size
The number of individuals in a population at a given time
Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction
Ecologists often use sampling techniques to estimate population size.
Did You Know? The passenger pigeon was once North America’s most abundant bird. Hunting drove them to extinction in less than 100 years.

10. Estimating Population
How can you estimate the population of trees in this valley?
WHY NOT COUNT THEM ALL?
WHY IS SAMPLING NEEDED?

11. Random Sampling

12. Mark and Recapture
Common way of estimating population size

13. Population Density What is population density?
What are advantages and disadvantages of high and low density?

14. Population Density Measure of how crowded a population is
Larger organisms generally have lower population densities.
Low population density: More space, resources; finding mates can be difficult
High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators

15. Population Distribution
How organisms are arranged within an area:
RANDOM
CLUMPED
UNIFORM
Occurs when individuals hold territory or compete for space
Plants in a desert
Occurs where resources needed are found throughout
Wildflowers in a meadow
Most Common. Occurs where resources are together
Water hole in desert, humans in cities

16. Many bird species are territorial
Many bird species are territorial. In territorial birds species, what kind of population structure would you expect?
UNIFORM

17. Population Distribution
Random distribution: Organisms arranged in no particular pattern
Uniform distribution: Organisms evenly spaced
Clumped distribution: Organisms grouped near resources; most common distribution in nature

18. What type of distribution?
CLUMPED
WHY?

20. Ocearch - tracking shark movement
This site tracks shark movement by tagging sharks
In 2015 Mary Lee was at one point less than ¼ mile from the shore

21. History of Black Bear Sightings in New Jersey

22. Why is it important to estimate the populations of sharks and black bears?