Transmitter harness trials
To help monitor takahē in the Murchison Mountains and on some island and mainland sites takahē are often fitted with transmitters. Most of these transmitters are fitted to takahē using a backpack harness which fits over their wings. In recent years backpack harnesses have been associated with bone remodelling and soft tissue injuries in takahē. These effects increase with the length of time that the harness is worn. As a result, current transmitters are removed after three years, and we’re searching for an alternative transmitter attachment method.
Two alternative designs are currently being trialled, to assess their impact on takahē health, survival and reproduction. A further study to assess the energetic cost of transmitter wear is planned.
Leg Mount transmitters, which are commonly used on kiwi and, as suggested by their name, are mounted high on the leg of takahē. We have trialled these on six birds at the Burwood Takahē Centre.
Flight harness transmitters are another option being trialled. Similar harnesses are used on whio, weka, pateke, kea and kaka. Flight harness transmitters sit on the back of takahē like the current backpack transmitters but are fitted around under the chest taking pressure off the patagium (top part of the wing where it joins the main body of the bird). The flight harness transmitter has a weak link on the chest section designed to break if the transmitter gets caught up in anything. We started by working with takahē (Kawa and Tumbles) at the Te Anau Bird Sanctuary to modify the design used for whio/blue duck. We then trialled them on birds at Burwood and with good results thus far have extended the trial to takahē at a number of secure sites.
There are sex biases at some takahē sites, with a variation between female-biased and male-biased populations. The reasons for these sex skews are not known, so a research programme is attempting to determine whether factors such as supplementary feeding or parent condition are responsible.
Takahē can carry high loads of the parasite coccidia, usually found in the gut. The species of coccidian that infect takahē, and the range of loads, is unknown. A veterinary study is determining the impacts of coccidia on takahē, to develop a screening protocol and treatments.
Pukeko and Australasian harriers are known to prey on takahē, but their impacts have not been measured. This study will determine the effect of these native predators on takahē populations.