Where is a topic sentence located in a paragraph?

Usually the topic sentence is the first sentence in a paragraph. The topic sentence makes a statement about some topic and the rest of the paragraph explains the topic sentence or gives examples of the topic sentence.

For example if this was the topic sentence

There are three living species of Kiwi all of which inhabit New Zealand.

Then this paragraph would probably tell us what the three species are and where they live in NZ.