Quadrat

Plants don’t move about, yet there may be too many to count. Biologists only count small areas and multiply up, to get a population estimate.

They tend to use a small sampling square – called a quadrat.

Animals aren’t as co-operative as plants – they move around.

Therefore to be able to count them you have to trap them in a way that they are not harmed and then release them.

To get any idea of the population size of an animal, scientists trap them, mark them in some way, then release them again.

If that animal is re-caught, then the scientist will know.

In recent years, with developing technology, some scientists have been able to follow animals using satellite tracking.