23 Mar 2017

Tracking kākāpō the smart way

From Our Changing World, 9:04 pm on 23 March 2017

Egg-timer technology. Check mate transmitters. They sound like something from a modern kitchen and maybe a robot that plays chess. But actually, they’re part of an arsenal of smart technology that is revolutionising how the Department of Conservation (DOC) manages the endangered kākāpō.

kākāpō with transmitter

A young kākāpō with the aerial of its backpack transmitter visible. Photo: Andrew Digby / DOC

Like many rare birds, kākāpō wear small backpack radio transmitters so they can be located in the dense forest on the remote islands where they live. But in recent years these transmitters have become multi-purpose, giving DOC rangers important insights into the behaviour of the birds – from a distance.

The transmitters collect and store information about each bird’s activity and then send out that information as a sequence of beeps. The DOC ranger counts the sequence of beeps, and the resulting series of numbers contains the vital information.

Smart kākāpō transmitter

A smart kākāpō transmitter - they are worn like little backpacks. Female kākāpō have an egg timer transmitter, while male kākāpō wear a check mate transmitter. Photo: Andrew Digby / DOC

Egg-timer transmitters were originally developed for kiwi. They contain an activity sensor, and when the bird’s activity drops to a low level it is an indication that it is incubating an egg on a nest.

These egg-timer transmitters are now used for female kākāpō, to show when they are incubating eggs. It indicates what length of time she has been sitting on the nest, and how often and how long she leaves the nest when she is feeding.

A proximity sensor in the female’s transmitter can detect when another kākāpō transmitter is nearby. This ‘stranger danger’ mode is useful for indicating when an unwanted bird – perhaps a nosy teenager – might be bothering small chicks.

Young kākāpō with a transmitter

As soon as young kākāpō become mobile and start to wander from the nest, they are fitted with a smart transmitter, visible on the back of this youngster. Photo: Andrew Digby / DOC

The check-mate transmitter has been specially developed for male kākāpō. The rangers want to know which females each male has mated with, and also how effective that mating might be. A proximity detector shows which females have spent time with the male, how long they were together, and how active they were together. The more active and the longer the behaviour goes on for, the higher the mating score.

Leigh Joyce tracking kākāpō

Kākāpō ranger Leigh Joyce tracking the rare flightless parrot on Hauturu - Little Barrier Island. Photo: RNZ / Alison Ballance

At the moment, the rangers walk around until they detect a signal from a bird’s transmitter. In future, a series of radio repeaters will automatically detect the signals and send that information to a ranger’s computer.

This smart technology is becoming more important as kākāpō numbers are increasing, from a low of 51 known birds in the early 190s, to today’s 154 birds.

Kākāpō now live on three predator-free islands – Hauturu / Little Barrier Island in the Hauraki Gulf north of Auckland, Whenua Hou / Codfish island near Stewart Island and Anchor Island / Pukenui in Fiordland’s Dusky Sound.

Kākāpō don’t breed every year, but time their breeding to coincide with the irregular mass fruiting of rimu trees. The summer of 2016 was a bumper breeding season for the endangered kākāpō on all three islands - 32 chicks successfully fledged, bringing the total population to 154.

There was no breeding activity in the populations on Whenua Hou and Pukenui in the summer of 2017, but kākāpō ranger Leigh Joyce says that male kākāpō on Hauturu were booming, which is how they attract females. While several females moved closer to the males for a few days, there has been no indication from the check mate transmitters of any mating.

The kākāpō recovery team have just counted the proportion of unripe fruit on rimu trees on Whenua Hou and Pukenui, as this gives an early indication of the likelihood of kākāpō breeding. The amount of fruit is very low so there will be no kākāpō breeding on the southern islands in the summer of 2018.

Alisha Sheriff and kākāpō

DOC ranger Alisha Sheriff carries out the annual transmitter change on a kākāpō. Photo: Jake Osborne / DOC