1. Environmental Science
Studying Populations
Ch. 1.2

2. 1. Population Density The number of individuals in an area
Population Density= Number of Individuals
Unit Area

3. 2. Determining Population Size
Direct observation
Counting one by one
Indirect observation
Notice other signs such as animal tracks
Sampling
Taking an estimate: an approximate count
Mark-and-capture studies
Capture an animal, mark that animal, watch for behaviors, numbers

4. 3. Changes in Population Size
Returning to the area often
Using one of the methods to determine population size
Scientists can tell changes in size
Death
Births
Immigration: moving into a population
Emigration: leaving a population

5. 4. Limiting Factors
An environmental factor preventing a population from increasing
Food
Carrying capacity: largest population that an environment can support
Space
crowded
Weather conditions
Hurricanes
Climate changes