The mating system and genetic variation of an introduced, closed, high-density North Island brown kiwi (Apteryx mantelli) population

A project undertaken by Massey University, Auckland, New Zealand, and supervised by Assoc. Prof. Dianne H. Brunton and Birgit Ziesemann

Background

North Island brown kiwi are declining at an average rate of 5.8% per year due to habitat destruction and predation from introduced mammals (2,5). Thus, most of their populations are suffering significant recruitment failure and usually occur at low densities (2,5). Research conducted on low-density populations report that kiwi form long-term monogamous pair bonds (4,6). However, there is still little known about the social behaviour of the North Island brown kiwi, despite the fact that this species possessess some unique characteristics of reproduction and parental care which lead to the possibility that this species could be polyandrous. Kiwi mating behaviour may be dependent on population density and the availability of potential mates. By studying a high-density population we may learn how kiwi behaved socially in pre-human New Zealand and how flexible their mating system may be under different ecological conditions.

The pressures of predation and habitat loss have prompted translocations of small numbers of kiwi to predator-free offshore islands as part of a management tool in kiwi conservation (1). However, the benefits of translocating kiwi to these safe refuges focus on short-term recovery of the species, whereas long-term consequences such as loss of genetic variation and inbreeding are neglected (3). The kiwi population that is the focus of this research originated from a small founder population which was introduced to an offshore island c. 43 years ago. To date, there is a lack of knowledge about the effects of population bottlenecks on the genetic variation of closed, translocated kiwi populations.

Research aims

The overall aims of this research project are to investigate the effects of population density on kiwi mating behaviour, and the effect of a small founder population on the genetic diversity.

Objectives and Methods

The study will be conducted using two main methods: behavioural observations and genetic analysis.

The objectives and methods are:

1) Determine kiwi social organisation and mating system by collecting field data on nesting/roosting behaviour, spacing and pairing behaviour of radio-tagged kiwi.

2) Investigate the level of relatedness between individuals to determine the degree of inbreeding and estimate the genetic variation of this study population. This will be conducted using microsatellite DNA profiling.

3) Determine the underlying genetic mating system by paternity analysis using microsatellite DNA profiling. This will be related to the social mating system as determined in objective 1.

Outcomes

Effective kiwi conservation management requires a better understanding of kiwi life history characteristics, which includes genetic variation and relationships between individuals, in order to prevent the species from losing viability or going extinct. This research will contribute to understanding of the ecology of this species as a whole by closing the gap in knowledge about the behaviour and genetic diversity within a closed, high-density population, 43 years after introduction.

For more information on this research project please contact Birgit Ziesemann B.Ziesemann@massey.ac.nz, or Dianne Brunton D.H.Brunton@massey.ac.nz

References:

(1) Colbourne, R. 2005. Kiwi (Apteryx spp.) on offshore New Zealand islands: populations, translocations and identification of potential release sites. In: DoC Research & Development Series 208, pp. 24. Wellington: Department of Conservation.

(2) Hitchmough, R. 2002. New Zealand Threat Classification list-2002. In: Threatened species occasional publication 23, pp. 210.

(3) Jamieson, I. G., Wallis, G. P. & Briskie, J. V. 2006. Inbreeding and endangered species management: Is New Zealand out of step with the rest of the world? Conservation Biology, 20, 38-47.

(4) McLennan, J. A. 1988. Breeding of North Island brown kiwi, Apteryx australis mantelli, in Hawke's Bay, New Zealand. New Zealand Journal of Ecology, 11, 89-97.

(5) McLennan, J. A., Potter, M. A., Robertson, H. A., Wake, G. C., Colbourne, R., Dew, L., Joyce, L., McCann, A. J., Miles, J., Miller, P. J. & Reid, J. 1996. Role of predation in the decline of kiwi, Apteryx spp., in New Zealand. New Zealand Journal of Ecology, 20, 27-35.

(6) Taborsky, B. & Taborsky, M. 1999. The mating system and stability of pairs in kiwi Apteryx spp. Journal of Avian Biology, 30, 143-151.

 

Figure 1. Adult North Island brown kiwi (Photo: Carryn Hojem)

Figure 2. Birgit Ziesmann holdiing a North Island brown kiwi egg (Photo: Sander Holtuijsen)

Figure 3. Birgit Ziesmann radio tracking kiwi (Photo:Luis Ortiz Catedral)

Figure 4. North Island brown kiwi chick (Photo: Birgit Ziesmann)