Population dynamics of kākāpō

This measure relates to indicator 1.4.2 – Security of threatened and at risk taxa.

Background

The kākāpō is one of New Zealand’s unique national treasures. However, this bird – Nationally Critical under the New Zealand Threat Classification System – is found on only a small number of New Zealand’s offshore islands and has a population size of < 220 individuals, making infertility, disease and low genetic diversity major threats. DOC has been monitoring kākāpō populations since 1990.

One of the two juvenile kākāpō which died of aspergillosis in September 2019.

What did we measure?

The entire kākāpō population has carried radio transmitters and been closely monitored since 1990 to allow accurate determination of the population demographics.

What did we find?

• There was no kākāpō breeding in 2020 (Figure 1).
• 21 kākāpō received diagnosis and treatment at veterinary hospitals until February 2020 for the fungal pneumonia aspergillosis contracted in April–May 2019. A secondary outbreak of aspergillosis occurred on Codfish Island / Whenua Hou in September 2019, killing two juveniles.
• Two adult and two juvenile deaths occurred between 1 July 2019 and 26 May 2020 (Figure 2).
• There are almost equal numbers of adult males and adult females in the population, but more juvenile males than juvenile females (Figure 3).
• Research projects are ongoing and investigating many areas relating to kākāpō management, including aspergillosis, other diseases, genetics, diet and microbiology.

Figures

Figure 1: Changes in the adult and juvenile kākāpō population since 1977. Population totals apply to 1st January each year.

Figure 2: Annual number of kākāpō deaths since 1991. Adult means >5 years old and Juvenile means from 150 days — 5 years old.

Figure 3: Age structure and sex ratio of the kākāpō population. Adult means >5 years old, Juvenile means from 150 days - 5 years old and Chick means <150 days old.

Data quality

This measure is classified as a partial measure and complies with the data quality guidelines used in the Environmental Reporting framework.

Intensive management and low numbers of individuals allow regular and complete censuses of the entire population. Therefore, measurement of the key demographic parameters reported here is extremely accurate.

Glossary of terms

Aspergillosis is a fungal infection that commonly causes respiratory disease in birds, particularly those that breed in cavities. It can cause both upper (nasal, sinus, eye and trachea) and lower (lungs and air sacs) respiratory problems or more broadly distributed systemic infections that can be fatal.

Additional resources

Lee, W.; McGlone, M.; Wright, E. 2005: Biodiversity inventory and monitoring: a review of national and international systems and a proposed framework for future biodiversity monitoring by the Department of Conservation. Landcare Research Contract Report LC0405/122 for the Department of Conservation, Wellington (unpublished). 213 p.

McGlone, M.; Dalley, J. 2015: A framework for Department of Conservation inventory and monitoring: intermediate outcomes 1–5. Landcare Research Contract Report LC2427 for the Department of Conservation, Wellington (unpublished). 75 p.