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. The next intervention was eradication in 1993 of the Polynesian rat, known to Māori as kiore, which was destroying seedlings and competing with birds for food. The kiore were killed by an aerial drop of poisoned bait, which was controversial due to its lack of planning and the effect on other wildlife. For instance, 90% of pūkeko on the island were killed, though the resident takahē were kept in an enclosure for the duration of the poisoning. Eighty-seven species of birds have been observed on or near the island. Eleven native species have been translocated to the island as part of the ongoing restoration project. These are red-crowned parakeet (kākāriki, Cyanoramphus novaezelandiae), North Island saddleback (tīeke, Philesturnus rufusater), brown teal (pāteke, Anas chlorotis), whitehead (pōpokotea, Mohoua albicilla), takahē (Porphyrio hochstetteri), little spotted kiwi (Apteryx owenii), stitchbird (hihi, Notiomystis cincta), North Island kōkako (Callaeas wilsoni), fernbird (mātātā, Poodytes punctatus), North Island tomtit (miromiro, Petroica macrocephala toitoi), and rifleman (titipounamu, Acanthisitta chloris). Non-avian translocations include 60 tuatara in 2003, Duvaucel's gecko in 2006 and a large insect wetapunga in 2011. Non-native species still present include the Australian brown quail. The success of the conservation project encouraged the creation of a number of similar projects around the Gulf, such as on Motuihe, Motuora and Motutapu. The closest land on the tip of the Whangaparaoa Peninsula, Shakespear Regional Park has recently (2011) also become a mammalian pest-free fenced sanctuary, increasing immigration of the birds on Tiritiri to the nearby mainland. A ferry service runs from Auckland Ferry Terminal and Gulf Harbour, and guided tours are available. It is a popular destination for daytrippers, with trips often fully booked, attracting some 30,000 visitors annually, who enjoy an intensity of birdsong rarely heard on the mainland. The island has hosted several tens of thousands of conservation volunteers.