The kiwi behaves like a smaller, less liquid aussie. Dairy prices, Chinese demand and Reserve Bank of New Zealand policy drive it, and its correlation with AUD/USD is usually high enough that holding both is close to doubling one position.
Lower liquidity shows up as slightly wider spreads and sharper moves during the asian-session, and as poor fills around data releases.
Example: AUD/USD and NZD/USD have a 30-day correlation of 0.9. A trader long one standard-lot of each believes they hold two positions but has roughly the risk of 1.9 lots of a single one. See currency-correlation.
Related: aussie, currency-nickname