The island was chosen as a unique and protected place to provide a public window for rare New Zealand native birds on the edge of a large city and it also lacked introduced predators such as mustelids which were present on the mainland. At that time, although the island was devoid of suitable habitat and food sources, the hope was that native forest would regenerate naturally. It became apparent that natural afforestation was happening very slowly because a forest can only grow at its margins, and the island was covered mostly with dense grass and bracken fern. A plan was formulated to establish a nursery to collect cuttings and seed in order to expand the small pockets of forest habitat that were left in some of the valleys. Pohutukawa was chosen as the main tree as it would eventually provide perches and roosts for birds who would then excrete the seed of the fruits that they had been eating, which would then germinate around the pohutukawa.