1. Determining Population Sizes

2. 4 Ways of Determining Population Size
Direct Observation
Indirect Observation
Random Sampling
Mark-and-recapture study

3. Direct Observation Definition
to count each and every organism of a population in an area.
Pros
Exact population count
Cons
May take a long time
Example
Counting all of the crabs that live in a tide pool

4. Indirect Observation Definition
to observe signs of an organism rather than the organism itself.
Pros
Not as time consuming
Cons
Evidence of an organism does not tell you exactly how many there are; may be inaccurate
Example
Counting the number of nesting sites in an area

5. Random Sampling Definition
Finding a method of randomly choosing individuals and then multiplying the number of individuals by the area
Pros
Fast data collection
Cons
Inaccuracy
Example
Count the number of penguins in a small area, then multiply to find the number ion the entire colony.

6. Mark-and-recapture Study
Definition
to catch, mark, release and recapture an organism. Then use mathematical formulas to estimate the total population.
Pros
Accurate
Cons
Expensive, time consuming
Example
Counting hawks with bands of their legs

7. Sea turtle mark-and-recapture lab