Jane Healy, Auckland Zoo
We’re very happy to share that two rare matuku-hūrepo (Australasian bittern) found severely emaciated and dehydrated in South Auckland last month are on the road to recovery at Auckland Zoo’s vet hospital.
Found throughout New Zealand and parts of Australia, today there are less than 1000 of these ‘Nationally Critical’ taonga here in Aotearoa where 90% of wetlands’ habitat has been lost - primarily due to being drained for urbanisation and agriculture.
On 1 May, following a short stay at Animal Referral Centre, our Department of Conservation (DOC) colleagues brought in the first matuku-hūrepo - a female juvenile found in a residential backyard in Pukekohe. Just over two weeks later a second female juvenile, found in Karaka, was brought into our hospital by BirdCare Aotearoa.
While full health checks and X-rays under general anaesthetic revealed no physical injuries, both birds were critically emaciated and dehydrated – weighing just 468grams and 570grams respectively. Through specialist treatment (including initial fluids administered subcutaneously) and plenty of nutritious food, both birds have been steadily gaining weight. The first arrival is now tipping the scales at a healthy 900grams and the second is tracking well at around 800grams.
“Matuku are an extremely cryptic and secretive species that typically don’t do well in human care,” says our Zoo vet, Dr Adam Naylor.
“For this reason, the team and I were mindful of the need to create a calm, quiet environment for them, minimise handling and ensure we gave these very underweight birds just the right amount of food and calories.
“Feeding highly malnourished birds like this too much too quickly can cause a condition called ‘re-feeding syndrome’ - severe electrolyte imbalances that can lead to multiple organ failure and even death. Conversely, if they don’t get enough food, then they won’t put on weight quickly enough and may succumb to starvation. It’s a delicate balance!
“Fortunately, both birds self-fed from day one which was a huge advantage. In the wild they eat a range of small animals including birds, fish, frogs, and invertebrates. Here at the vet hospital, they’ve been given invertebrates and dead mice, chicks, and fish,” explains Adam.
To aid in their recovery, the vet team, with the help of the Zoo’s awesome browse team, have provided these shy and secretive makutu-hūrepo with plenty of plant material to retreat and hide in, and naturalistic areas that include a grass yard and water pools.
While both avian patients are not yet out of the woods, the Zoo, along with DOC and iwi, are hoping that they will regain full health so that they can be released back to the wild.
DOC’s wetlands bird science advisor, Harry Caley, says food availability and accessibility is becoming a growing issue for matuku-hūrepo.
“Where nests are located may be competitive for good quality food like fish and macroinvertebrates, and water quality may also be low with high-sediment levels making it harder for these visual hunters to see prey in the water.
“The 2022-2023 spring/summer season was particularly wet, flooding lots of sites and introducing lots of sediment into waterways, so this has likely compounded these issues. If a fledgling starts its independent life with limited foraging success, then it’s going to struggle to find better places to forage, and possibly can’t expend too much expensive flying energy to search in new areas, so it’s sadly a cascade of unfortunate events,” says Harry.
Matuku-hūrepo are an important apex predator of wetlands that shares the top of the food chain with kahu (harrier). They travel throughout the Auckland region and other surrounding regions and are one of many species impacted by the massive loss and fragmentation of wetlands habitat.
“Prior research has shown that matuku-hūrepo are highly mobile and require a network of sites to survive, which can sometimes see them moving as far as 330km in one journey,” says DOC science advisor/mobile species, Emma Williams.
We can all be kaitiaki for wetlands
