The kākāriki of Okiwi
by Serena Simmonds (Massey Universsity)
The Great Barrier Island Environment Trust, working with Okiwi School and other community members has initiated a project to find out more about the remnant kākāriki population of Okiwi.
The research is being funded by the Trust, and initially includes two aspects—nest searching and population counts. Nest searches in the study area were carried out in December 2017 and February 2018. Locating potential and active nests of kākāriki / red-crowned parakeet (Cyanoramphus novaezelandiae novaezelandiae) was identified as a key component of the research, as nest protection is an important requirement for the management of a species, particularly in areas where predators are present. This strategy has been used successfully on Norfolk Island for the Tasman parakeet (Cyanoramphus cookii)1.
Why kakariki remain in Okiwi
The population of kākāriki persist in the Okiwi Valley despite the presence of ship rats and feral cats. These birds are sociable and vocal, especially when in small groups and are well known to local residents.
The number of kākāriki resident in Okiwi is unknown, with no formal count or monitoring known to have been undertaken. Single birds and birds in groups of up to a dozen have been sighted in the Okiwi River and adjacent forested areas.
The species is believed to nest in mature puriri trees along the Okiwi River, most likely in the Okiwi Reserve – where Okiwi School has carried out rat control for many years.
The yellow track shows areas of the Okiwi Valley where searching was carried out for kākāriki nests in December 2017. A subsequent search in February 2018, covered further areas with mature puriri trees. Further searches are planned for later in 2018.
Nest search methods
On predator free islands kākāriki can be found nesting in flax, logs, burrows on the ground, and in pōhutukawa (Metrosideros excelsa) and puriri (Vitex lucens) trees.
The presence of rats and cats in the Okiwi Valley mean that the Aotea Great Barrier Island kākāriki are highly unlikely to be successfully using ground level nest sites.
Kākāriki prefer mature trees with access to water. Sections of bush in the study area were identified as potential nest sites where they had mature puriri trees and were close to watercourses. Permission was sought from owners of each property prior to the undertaking the searches.
Literature on this species informed the identification of potential nest trees. The literature notes that natural nests in puriri trees were found in alive and healthy trees that were greater than 300 mm diameter at breast height, indicating mature trees2,3.
Puriri tree search and cavity check
Unoccupied nest in mature puriri tree, Okiwi Valley. Photo: S Simmonds
Each section of identified bush was searched and suitable puriri trees were identified. Cavities in puriri trees are formed when a tree limb drops off and the scar left behind rots away and becomes hollow. For this reason, young trees were not searched as they most often have all of their limbs attached. Every tree that fits the criteria was searched for cavities, and if a cavity was found, it was examined for bird activity if accessible.
Bird activity included droppings, feathers, complete eggs or shell fragments, chicks or adult birds. If adults, chicks, or eggs were seen it was recorded as an active nest. If only presence indicators (droppings and feathers) were noted, it was recorded as unoccupied.
Any cavities with no bird activity, but otherwise suitable (for example a dry hollow with a large enough cavity), were recorded as potential nest sites. All active nest sites, unoccupied or potential sites had their location recorded.
Nest search results
Four nests were found with signs of bird activity: one active, two unoccupied, and one considered a possible nest. The active nest was found in the Okiwi Reserve. The entrance to the nest was formed by a fallen limb and is approximately 5 m from the ground and is roughly 40 mm long and 20 mm wide. Two birds were observed near this nest and one was seen entering the entrance.
The first unoccupied nest was found in a medium size puriri tree near Mabey Road and was about 1.6 m from the ground with a small entrance. This nest had a few feathers found inside it but no sign of current bird activity.
The second unoccupied nest was found on the short scenic walking track that crosses through the Whangapoua Reserve off Aotea Road. This nest was in the base of a large puriri tree, approximately 0.5 m from the ground. This nest had a skeleton and feathers present but no signs of current activity. A possible nest was also found on private property close to the estuary in a large puriri by the stream. A bird was perched, calling, approximately 6-7m from the ground in this tree, near a hollow. The bird was gripping on to the tree and proceeded to go upside down and stick its head into the roots of a widow maker (Collospermum hastatum), near the hollow.
A total of 49 potential [kākāriki] nests were identified in puriri trees around the Okiwi Valley area.
Some of these (n=4) were found in the bush area adjacent to the Department of Conservation offices, while the majority were found in the Okiwi Reserve beside the school and private properties bordering the Okiwi Stream. Some of the trees had multiple hollows at varying heights. Some of the potential nests had rat droppings present.
Interior of a potential nest site with rat droppings present, Okiwi. Photo: J Scarlett
Kākāriki are vulnerable to rats
The results show that there are kākāriki using the Okiwi Valley area as a nesting site. While only one active nest was found, it can be assumed that there are more nests in the area. Considerable bird activity occurs in this area, such as perching around potential trees, calling and flying through.
Rats present the biggest threat to this species, as rats can enter the cavity and destroy eggs and chicks on the nest, while also attacking chicks that have recently fledged.
Some of the potential nests that were found contained rat droppings which confirm that rats are entering nests. One nest was found with feathers and a skeleton of a kākāriki inside, suggesting that a bird had been killed on the nest. The stage of the feathers indicate that it was either a pre-fledged juvenile or an adult, and so likely cause of death was either that it starved or was killed by a predator, most likely a rat.
Conclusions and recommendations
The results of the research to date are important as they show that there is a need for nest protection in the Okiwi Valley. After talking with residents of the area, it is clear that this population of kākāriki are an important part of the environment, both culturally and scientifically. Nest protection for this species should be provided, as well as nest monitoring, around identified active and potential nests. It is essential that the community continue to feel a sense of ownership and engagement with this species and to be involved with any protection initiatives. Traps placed near active nests will reduce rat presence around the tree and importantly allow juveniles to fledge and have a chance at survival.
Red crowned parakeet at nest hole in Okiwi.
Mature puriri trees are likely to be the only trees with suitable nesting sites.
Photo: Department of Conservation
Nests could also be monitored with night vision cameras to provide insights into chick development while allowing predators entering the nest to be identified - particularly useful for nests that are difficult to reach.
Kākāriki can produce clutches of eggs throughout their breeding season and may not have established a nest at the time of this study. Further nest searching at different times of the breeding season will add to our knowledge of this species in Okiwi.
This population of kākāriki are an important part of the story that involves the translocation of kākāriki around the North Island, to areas such as Tiri Tiri Matangi Island, Tawharanui Regional Park, Motuihe Island and nearby Little Barrier Island (Te Hauturu-o-Toi)4,5. The population could also be important for future translocations and the mixing of genetic material in this species. Without nest protection, this species may reduce so much in numbers that they become functionally extinct, which would be a great loss.
Notes
1Director of National Parks. 2010. Norfolk Island Region Threatened Species Recovery Plan. Dept. of the Environment, Water, Heritage and the Arts.
2Ortiz-Catedral, L., & Brunton, D. H. 2010. Success of translocations of red-fronted parakeets Cyanoramphus novaezelandiae novaezelandiae from Little Barrier Island (Hauturu) to Motuihe Island, Auckland, NZ. Conservation Evidence, 7, 21-26.
3Greene, T. C. 2003) Breeding biology of red-crowned parakeets (Cyanoramphus novaezelandiae novaezelandiae) on Little Barrier Island, Hauraki Gulf, New Zealand. Notornis, 50, 83-99.
4Miskelly, C. M., & Powlesland, R. G. 2013. Conservation translocations of New Zealand birds, 1863–2012. Notornis, 60, 3-28.
5Ortiz‐Catedral, L., & Brunton, D. H. 2009. Nesting sites and nesting success of reintroduced red‐crowned parakeets (Cyanoramphus novaezelandiae) on Tiritiri Matangi Island, NZ. NZ Journal of Zoology, 36(1), 1-10.
Environmental News Issue 39 Winter 2018