Amazing drone images of an elusive and critically endangered wetland bird are helping DOC locate and understand nesting activity.
Bittern/matuku-hūrepo have just started building nests and laying eggs in wetlands and lakeshores around the country. There are estimates of fewer than 1000 of these birds left nationwide and fewer than 50 in Canterbury.
The elusive bittern is incredibly hard to find and monitor due to its camouflage, shy nature and wetland habitat, which is difficult to access. Traditional monitoring has focused on male calls and so relatively little is known about the females and their nesting outcomes. DOC is now using drone thermal imagery combined with high resolution video to detect them.
DOC Biodiversity ranger Allanah Purdie says it's a gamechanger as there's no way they would be able to efficiently find bittern nests and chicks on foot without causing undue disturbance.
"The drone pictures have incredible detail. We are able get up close to their nests without disturbing them and see how they're faring.
"In Canterbury, bitterns nest primarily around Te Waihora/Lake Ellesmere and in wetlands along the coast. It's vital we understand how many there are, their fledging success rate and causes of failure," she says
Drone operator Daniel Manchester, whose company Proform did the filming, says the technology is an incredible tool for conservation.
"It's like being able to find a needle in a haystack, being able to pinpoint a small white dot of a bittern with thermal imaging and then zoom in to see high-definition pictures in a completely camouflaged habitat. We operate using protocols developed by DOC and in a way which doesn't disturb the birds at all. This technology is getting better incredibly quickly, and it feels good to be involved in conservation and helping nature," he says.
Allanah Purdie says the bitterns need all the help they can get.
"Their habitats like Te Waihora in Canterbury are not in great shape and often we see starving bittern fledglings popping up in other more urban areas, searching for food. It is important for us to better understand the impact that chick starvation is having on the bittern numbers, and nest monitoring with drones is helping reveal that picture," she says.
Bittern feed on small fish, like bullies and tuna/eels which are diminishing in numbers. In summer when the water in the lake is low and warm, those fish move away from the lake margin and into cool deep streams where bittern can't hunt them.
Spring sees people around Aotearoa taking part in monitoring and recording bittern calls at dawn and dusk through the Love Bittern Project 'Matuku Muster' which runs until the end of November.
Allanah Purdie says everyone has a part to play in helping save the bitterns.
"The bittern are our ecosystem health indicator, and if we can improve the health of our freshwater and fish life, our children's children will continue to hear their spine-tingling booms every spring. With only 50 left in Canterbury, it's vital that we help them survive," Allanah says.
