Got this from google, scientists count a species population by first knowing the population in a certain area or small geographical sample location then multiply the result by the total area.
Species population cannot be determined exactly.Scientists use sampling to get an estimate of things they cannot easily count.
EXPLANATION:
A population is presented as,all the bodies of one kinds living mutually in one area at the same time. All of the people living together in one town are acknowledged a population.Scientists keep record of the variation (increase or decrease) of population numbers to make determinations about concerns that affect that population.It is often not practical or even possible to count all the members of a population. A population can be so large that computing it would be like trying to figure out the number of grains of sand on a beach. Animals can be hard to count because they live underwater, move throughout a lot, or are only active at night. To get around these counting problems, scientists take data from just a small part of the population called a sample. They take several samples and then use the average proportion of those samples to calculate an estimate of the entire population size.
