This article was prepared by postgraduate student Ana Baral as part of the ECOL 608 Research Methods in Ecology course. This marks the last of this year’s cohort. Thanks to the class!
Kakapo are found only in New Zealand where these magnificent green parrots struggle for their survival. Only a few of these large birds survive in their natural habitats and are listed as a critically endangered species. Kakapo are unusual parrots in that they become active at night, cannot fly and forage on plants. These birds are ‘treasures’ of New Zealand.
Kakapo are vulnerable to introduced mammalian predators. By the mid 20th century, only a few Kakapo were fighting for existence in Fiordland and Stewart Island. Between 1970 and 1990, all known Kakapo were moved to predator free islands. One such island was Maud Island, in the Marlborough Sounds, because it was free from feral sheep and goats as well as mammalian predators of the Kakapo. The natural forest of Maud Island, now a scientific reserve of 309 ha, was highly modified to pasture and farmlands in the late 1800s. The island was brought back into the conservation estate in 1972 and restoration began. Nine birds were taken to Maud Island between 1974 and 1981.
Fruiting species, including gooseberries, blackcurrants, guava and apple, were planted in 1975 to provide additional food for Kakapo. Since 1990, Kakapo have been provided with protein rich supplementary food , which includes apple, kumara (sweet potato), and the kernels of almonds, brazil nuts, sunflower seeds and walnuts, to induce breeding artificially.
In an effort to better understand Kakapo, Julie Walsh and Kerry-Jayne Wilson of Lincoln University and Graeme Elliott of Department of Conservation, New Zealand carried out research about home range size and habitat selection of Kakapo on Maud Island. At the time, there were 18 Kakapo on the island; four adult males, nine adult females and five juveniles.
All kakapo were fitted with small backpack radio-transmitters and the positions of birds were obtained at night for almost a year. They estimated seasonal home range size which varied from 1.8 to 145 ha. The home range was smallest in winter and the size varied individually in the use of habitats and plant species.
As a result of conservation initiatives, previously cleared and converted natural forest to pasture was changed to regenerating scrub of eight vegetation types. Nearly all Kakapo used the pine plantation in summer because they fed on pine needles, barks and young cones. Kakapo rarely roosted in the pines because pine has relatively open forest floor of the plantation, and the straight, often branchless, tree trunks. The Kakapo used the treeland scrub in the autumn because they were feeding on five-finger berries. The Kakapo avoided lowland scrub in all seasons and other vegetation types seasonally.
The researchers concluded that Kakapo were more that capable of surviving on highly modified Maud Island. However, despite supplementary feeding, the Kakapo have only bred on the island once. The lack of successful reproduction suggests that Maud Island’s vegetation does not provide sufficient high quality food to trigger or support breeding, though it is more than adequate to support non-breeding birds.