Survival, breeding success and habitat selection of North Island robins translocated to Karori Sanctuary
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Delia Small, M.Sc.
Ben Bell, Ph.D. (Supervisor),
School of Biological Sciences, Victoria University of Wellington
North Island robin
In May 2001, 38 North Island robins (Petroica australis longipes) were translocated from Kapiti Island to Karori Wildlife Sanctuary (KWS). Two more robins were translocated in August 2001 (which were by-catch from mist-netting bellbirds on Kapiti Island). A further 36 robins were translocated from Kapiti Island in May 2002. These translocations were the first flighted birds to be released into KWS and are the only known transfers from a predator-free offshore island to a predator-free mainland island.
In this study, Delia Small assessed the dispersal patterns, survival rates, habitats selected, territory sizes, and breeding success of the KWS robins, and compared them to other translocated robin populations.
Most robins dispersed within KWS, and established territories within 500 metres from the release site. The first robin group released had the best choice of available habitats. Their survival rate to one year was higher than other translocated mainland island robin populations.
Survival of progeny to independence, and then breeding age was higher than other mainland robin populations and is the highest rate of recruitment recorded for robins in New Zealand. The number of fledglings per female in the year of translocation was second to highest for the first robin group released compared with other mainland island translocated populations. The KWS robin population had one of the highest numbers of young per brood. The KWS robins also had lower dispersal rates, higher survival rates, larger territory sizes and higher breeding success, than most other robin populations studied.
Nesting North Island robin
Habitats selected by the KWS robins were generally comparable with those selected by other robin populations. Flat, moist areas with available tree ferns, as well as litter cover, were important factors.
The experience and age of robins influenced their dispersal rate, habitat selection, survival rate and breeding success. Less experienced young robins dispersed further from natal sites compared with the distance that translocated robins moved away from their release site. Dispersal rates increased and survival rates decreased for the later robin arrivals due to the general increase in robin numbers and increased competition for resources. The recruitment rate of robins into the population compensated for natural mortality rates, indicating the initial translocation success of the KWS robins.
This research provides valuable information that will help ensure further successful translocation efforts, both at KWS and elsewhere in New Zealand.
Papers & Presentations
Technical Summary, (pdf format, 226 kB).
Presentation by Delia Small "Survival, Breeding Success and Habitat Selection of North Island Robins (Petroica Australis Longipes) Translocated to the Karori Wildlife Sanctuary," (pdf format, 1.7 MB).
Related Links
General information about robins in the Sanctuary.
Glossary
- Natal: The area or territory where robins were hatched, i.e., post-natal dispersal is when robins disperse away from the territory where they hatched and establish their own terRritories.
- Progeny: The offspring from breeding robin pairs.
- Recruitment: Locally bred robins that successfully establish territories and breed.
- Translocate: A translocation is the artificial movement of an indigenous species from one location to another to establish new populations and/or boost existing populations (IUCN 1987). Another term used for translocate is "reintroduce" or "reintroductions".
Acknowledgements
This research was made possible thanks to:
- Annette Harvey, Faye Schaef, Joan Adams and Frances Gazley for their assistance with data collection.
- The KWS staff and volunteers, especially Raewyn Empson and Denise Fraiser, the Operations and Administration team, and John Shorland.
- The DOC staff on Kapiti Island.
- VUW staff Ben Bell (supervisor), Kevin Burns, and Shirley Pledger.
- Forest and Bird for the "Sharon Watson Fund".
Profile
Delia Small.
Photo by John Shorland.
Delia Small, M.Sc. Delia completed her Masters of Science in Ecology at Victoria University of Wellington, where she also completed a B.Sc. in Environmental Studies. Her B.Sc. focused on resource management. She then switched to biological sciences for her M.Sc.
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