Sometimes counting populations is easy. How many grapes are in my snack bag? But other times counting populations can be difficult. How many birds are flying around in a field? The number, location, and mobility of the individuals impact the ease at which they are counted.

Consider… Some populations are easy to count in one setting, but difficult in another – it would be easy to count 50 students if they were all seated at desks in one classroom, but scatter those desks all over the school and it’s more difficult to count those same 50 students. In other cases, you might find that within an area one population is easy to count but another difficult – 30 rocks in a pond are easier to count than 30 fish swimming around in that same pond.

What factors should be considered when counting populations?

1. Number – how many individuals need to be counted – a lot, or just a few. It’s easier to count a small number of individuals than a large number. And that goes for just about anything!

2. Location – where the individuals are located. Let’s say you’re counting the same number of flowers in two groups. For one group, all the flowers are in one flower bed. In the other group, that same number of flowers are growing throughout a field. Even though you’re counting the same number of flowers, it’s easier to count the ones in a bed because they’re all in the same place.

3. Mobility – if the individuals are moving. Now imagine you’re counting people on a playground. If those people are standing still, they will be fairly easy to count. However, if those people are playing tag and running all over the playground, they will be much harder to count.

These factors help us determine the most appropriate way to count a given population. In future posts we will discuss a number of ways to count populations, ranging from direct counts to various sampling techniques.