In 1939 New Zealand ordered three armed trawlers that were supposed to serve as minesweepers and escorts. The ships were named after birds inhabiting the islands. They were finished in late 1941, after the WW2 broke out.
Later in 1942 the Pom-Pom aft was replaced with a 20mm Oerlikon and two more Oerlikons were added next to the main gun (one on each side). Also the Type 271 radar was installed. These little ships sometimes referred as "pocket corvettes" have sunk two Japanese submarines: one was rammed and wrecked by Kiwi in January 1943, another was hunted down buy Tui and bombed by US seaplanes in August 1943. Moa was lost to Japanese aircraft in April 1943.
After the war the two surviving ships were used as patrol boats and for training.