The word Kiwi has multiple meanings:
The word Kiwi, used to describe people, is usually capitalised, and takes the plural form Kiwis. The bird's name is spelt with a lower-case k (excepting, of course, when the rules of grammar state otherwise) and, being a word of Maori origin, normally stays as kiwi when a plural is formed. Thus, two Kiwis = two people, whereas two kiwi = two birds.
See also
The Culture of New Zealand article also has subsections about Kiwiana and the word Kiwi.
