Estuarine Birds
The Project's Integrated Catchment Enhancement Plan calls for predator control of estuarine habitat between Mahakipawa and Te Hoiere estuaries, to protect at-risk native birds, namely fernbird and banded rail. Department of Conservation is leading this work as part of its Ngā Awa River Restoration Programme. Estuarine species are secretive and difficult to monitor, with complex habitats for predator control. Unfortunately, wetlands are also havens for introduced predators including rodents, possums and mustelids, who all favour the protection provided by these areas.
Drone trial to monitor birds
As part of this predator control, DOC is also looking to understand and monitor the current populations of the benefiting species, fernbird and banded rail. In December 2023, DOC trialled drones with thermal imaging as a possible tool to monitor them. Overall, DOC found this technology worthy of future exploration as these birds tend to be very secretive coupled with an estuarine environment that's difficult to search.
Current survey techniques for these at-risk birds are both labour-intensive and limited in accuracy. This means that any monitoring to measure the impacts of predator control on wetland birds needs further development to provide reliable measures of success. The idea of a thermal camera mounted on a drone was proposed as a survey technique to compare bird numbers following predator control.
During the trial, over a dozen banded rail were observed. While no fernbird were seen, this may have been due to the flight path of the drone, which was over rush beds rather than the scrubby estuary margins that typically are the favoured habitat of fernbird. DOC will explore the timing and flight paths for future surveys using this technology.
Tracking tunnels
In April 2024, DOC installed 20 tracking tunnels on a small trial site to learn more about the local predators for fernbird and banded rail. Current knowledge about predator control has focused on forested areas, but less is known about best practice in narrow ribbons of vegetation surrounding wetlands.
These new tracking tunnels are adjacent to an existing trap line set by the community and will inform DOC how to best set up an expanded network to control predators on a larger scale. With DOC planning to invest in a significant trapping network, this small trial area was chosen to gather evidence for what this network might look like.
