How do scientists determine the size of the Grevy's Zebra population? What method do they use for determining the number of animals in a herd?

There are two ways to determine the size of the population:
1. a ground count
2. an area census by small plane
The count is done by block or area. Five vehicles all go out at the same time and count all the zebras in each area. Then there's one plane that counts in the areas vehicles can't get to. This way you get a total ground census of the population.

The observations that we've been doing in Lewa and Wamba are how scientists determine the number of animals in a herd. We go into an area, count the zebras and then determine the number, age, and sex of all the zebras in the herd. In the case of a really large herd, the animals are counted section by section, and then added all together.

-- Ms. Russell