Bitterns are found throughout New Zealand - in the North Island they predominantly inhabit Northland, Waikato and East Coast wetlands; while in the South Island they mostly inhabit West Coast, Canterbury and Southland wetlands. The most important bittern site nationally is Whangamarino Wetland, a large and diverse wetland complex in the Waikato.
Bitterns are large, stocky birds, with streaky dark brown and beige plumage on their throat, breast, abdomen and thighs; and dark brown on the neck and back. The head is dark except for pale beige around the cheek, forming a pale eyebrow. Plumage can vary significantly and may be age related.
Bitterns are rarely sighted due to their exceptionally cryptic behaviour, inconspicuous plumage resulting in excellent camouflage and the inaccessibility of many wetlands. They are mostly active at dawn, dusk and throughout the night. Bitterns are occasionally spotted in the open along wetland edges, drains, flooded farmland and roadsides.
They are very sensitive to disturbance and will silently creep away to avoid detection, or adopt the infamous ‘freeze’ stance (with the bill pointing skyward) if approached. This allows bitterns to blend into many environments, whilst maintaining a close watch of surroundings. If an observer continues to advance on a bittern, then it will eventually take flight in a laborious manner.
Often the only sign of bittern presence in a wetland is the male’s distinctive booming call at the beginning of the breeding season. Each call sequence may consist of 1-10 individual booms, with an average of 3 booms. Boom sequences are repeated at regular intervals, and normally preceded with inhalations or gasps. Females are mostly silent, apart from producing an occasional ‘bubbling’ sound upon return to the nest, or a nasal ‘kau’ when alarmed. Bitterns in flight may produce a resonant ‘kau’ or ‘kau kau’.
The breeding season is extremely long, spread over a 10-month period. Females construct a reed platform nest amongst dense vegetation deep within wetlands.
A clutch of 3-6 eggs is produced between August and December (peaking in November), and then incubated solely by the female for 25 days. Chicks remain in the nest for 7 weeks and fledge from November to May. Bitterns are considered an indicator of wetland health, as they are dependent on the presence of high quality and ecologically diverse habitats, which are rich in food supplies (such as eels, fish, freshwater crayfish, aquatic insects, molluscs, worms, spiders, frogs and lizards).
Bittern numbers have declined drastically since the arrival of European settlers, with over 90 percent of freshwater wetlands now drained and cleared. Ongoing wetland degradation continues to be the chief threat, resulting in habitat modification and loss, reduced food availability and poor water quality. Other threats contributing to bittern declines include predation by introduced mammals (particularly cats, rats, dogs and mustelids), human disturbance of nesting bitterns, as well as power-line and vehicle collisions.
You can help bitterns by becoming involved in wetland conservation and reporting all sightings (or calls) to your local Department of Conservation office. Most importantly you can protect wetlands on your property by planting native vegitation to create riparian buffers and fencing waterways from livestock.
Sabrina Luecht
Wildlife Project Administrator
(supplied by The Isaac Conservation and Wildlife Trust)
Now, if I was to ask how many of you have seen a juvenile bittern or a bittern nest, I think it’d be safe to assume that most of you haven’t. And that’s saying a lot given that you are all wetland enthusiasts who regularly work and play in these kind of habitats.
So when we got a report that a female bittern chick had been found wandering along a road in Christchurch you can imagine our surprise. What was one of the most cryptic and secretive wetland birds doing on a road in the city? And the surprises didn’t end there – a few weeks later a second female bittern chick walked into a residential garage, only 500m from the location where the first bittern was found.
There had to be a nest nearby – but where?
Both bitterns were very skinny and clearly dehydrated. They were taken to bird rehabilitator Jackie Stevenson, who set about trying to fatten them up and get them feeding for themselves. In the meantime, local ornithologist Peter Langlands set about trying to find their nest.
Now this is no easy task. Bittern nests are tricky to find. A broody female bittern will build her nest by bending blades of raupo to form a floating platform that is perfectly hidden in the thick vegetation. And she’s not necessarily alone. Male bitterns can have multiple females, which all appear to nest within close proximity to each other.
Once a mother-to-be is happy with her nest she’ll lay between 3 and 5 eggs before starting to incubate. She hatches the eggs and rears the chicks alone, apparently chasing the male away if he tries to get too close. While incubating, she’s almost impossible to see as her streaked plumage blends perfectly in with the surrounding vegetation. Occasionally she’ll slip silently off the nest to feed, but only momentarily as this leaves her eggs vulnerable to predators.
After about 25 days, her eggs will hatch to produce little fluffy chicks with Albert Einstein inspired hairdo’s. These fuzz balls, emerge as masters of disguise straight from the eggs, and will adopt a perfect ‘freeze pose’ that looks similar to that of the adults if they are disturbed. Chicks fledge at about seven weeks old. However, there is some suggestion that they may start wandering from the nest as early as two weeks old - which is perhaps how one chick ended up on a city road and the other in a household garage.
Midway between the locations where these two birds were found lies Travis wetland, a 120 hectare swamp complex that has been restored over the last 15 years by the Travis wetland trust and the Christchurch council. It is the most likely place where these two birds came from. As it happens Travis is a noteworthy place, with an interesting history. In the 1960’s, this beautiful wetland was under threat from developers, who wanted to convert it to a residential area. Luckily, the locals had other ideas. They realised the importance of the site’s natural biodiversity, and argued long and hard for its protection. After a long battle that involved a petition signed by almost 7000 people, biodiversity won out, and in 1997 the site became a natural heritage park.
And lucky for bitterns that it did!
Since then, these two bitterns have done well in captivity and we were able to release them over the festive season - one along the Waimakariri river and the other at Harts Creeks. We attached radio transmitters to both bitterns, one of which was kindly funded by Ducks Unlimited. Both of these birds will be tracked regularly by local enthusiasts and, as female survival and breeding success is the secret to saving a species in decline, and these birds are the only females to carry transmitters at the moment - the information we gain will be essential for saving the species.
Emma Williams
And thanks to Gill Lundie for organising the school visit.
Emma Williams has continued working on the bittern project assisted by me and other volunteers.
Key points are:
John Cheyne
Coordinator Project Bittern (Matuku)
Living Water - the Fonterra/Department of Conservation partnership – is helping Ian Lupton create a sanctuary for an endangered native bird on his Northland dairy farm.
When Ian bought his farm - eight kilometres north of Dargaville – he saw no native wildlife on the property. This changed after he reduced the amount of nitrogen fertiliser and chemical spray being applied on the farm.
“Within three years frogs, eels, pheasants, and herons were common daily sightings. I even began seeing bittern fishing for eels in a canal and drainage ditches on the farm,” said Ian.
Australasian Bitterns, or matuku, are endangered native birds that live in wetland areas. The brown, heron sized birds, are very shy and have excellent camouflage. They feed mainly at night, on fish, eels, frogs, freshwater crayfish or koura and aquatic insects.
“Regularly seeing bitterns on my farm gave me the idea of establishing a bittern sanctuary because a successful dairy farm and native wildlife can go hand in hand,” said Ian.
Living Water is a 10 year partnership between Fonterra and DOC working with dairy farmers, iwi, conservation groups, schools and other agencies in five key catchments in significant dairying regions. The focus is on increasing ecosystem resilience and farm profitability, which includes improving water quality and increasing the abundance and variety of native wildlife in the catchments. With help from Northland Regional Council, Ian sought funding from Living Water for his bittern project.
Fonterra North Island Project Manager Tim Brandenburg said “Ian’s dream of creating a sanctuary for bitterns fits perfectly with Living Water’s goal to increase the variety Safe place: A Bittern takes a stroll near wetland edge. Photos: supplied. and abundance of native wildlife in our catchments.
“The first step in building the sanctuary, is finding out how many bitterns are living on the farm,” said DOC Ranger, Olly Knox, who is co-ordinating the sanctuary work.
“Male bitterns make a booming sound, with each male making its own distinctive sequence of booms. Living Water funding will be used to buy digital recorders to record the bitterns booming on Ian’s farm. The recordings will be analysed to establish the number of bitterns on the property,” said Olly. The funding will enable Ian to control stoats and feral cats. These predators eat bittern eggs and chicks. It will also be used to control weeds that smother native plants and trees. Enabling native vegetation to flourish on the farm will increase the habitat for the bitterns.
Living Water is also providing native plants and grasses to go on the banks of the canal and drainage ditches on the farm. This will create more bittern habitat, which will encourage more breeding.
“Riparian planting also improves water quality by reducing the run off of sediment and nutrients into the canal and drainage ditches. And it provides habitat for the fish, eels, frogs and aquatic insects in the waterways. Having more of these freshwater species will increase the bittern’s food supply,” said Olly.
Dargaville High School has supplied native trees, flax and grasses for the riparian planting. Enviroschools Northland secondary schools facilitator, Jacque Knight worked with teacher, Tim Pratt to establish the nursery. Jacque has also involved Dargaville High students in the bittern project.
“The students are making monthly visits to the farm to record sightings of bitterns, noting details of the vegetation and conditions they favour,” said Jacque. “These are secretive birds. If we can learn more about the habitat and conditions they like, we can recreate these as we build the sanctuary.”
Local iwi, Te Roroa, is supporting the establishment of the sanctuary as it will enhance the local habitat and contribute to a healthy environment for the Matuku. Northland Regional Council Land management adviser, Pete Graham, is working with Ian Lupton to implement a Farm Water Quality Improvement Plan on the farm. “Creating the bitten sanctuary meshes really well with our water quality improvement plan. Pete said “The riparian planting improves water quality and creates habitat for bittern.” Living Water programme Living Water is a 10-year partnership between Fonterra and the Department of Conservation Wetland: Ian Lupton near his bittern sanctuary. (DOC) working with dairy farmers, iwi, conservation groups, schools and other agencies to improve the health of five key catchments in significant dairying regions throughout the country.
Living Water is working to increase ecosystem resilience and farm profitability, which includes improving water quality and increasing the abundance and variety of native wildlife in the five catchments.
To achieve this includes planting native trees, shrubs and grasses along waterways. This reduces sediment and nutrient run-off into the waterways. Animal predators and weeds are also being controlled, enabling native wildlife and plants to thrive.
Living Water catchments are:
Fonterra is a global leader in dairy nutrition and is a market leader with our own consumer dairy brands in Australia/New Zealand, Asia/ Africa, Middle East and Latin America. The farmer-owned NZ co-operative is the largest processor of milk in the world, producing more than two million tonnes of dairy ingredients, value added dairy ingredients, specialty ingredients and consumer products every year. Fonterra is one of the largest investors in dairy based research and innovation in the world. Staff work across the dairy spectrum from advising farmers on sustainable farming and milk production, to ensuring we live up to exacting quality standards.
The weather was not wonderful, but Robin and Heather List are seasoned birders and the pair set off to Wario to check on birds and do a count.
Robin said “The expedition consisted of Heather and me. We have the gear and do wetlands in squalls right cheerfully, so there was no grumbling in the ranks, though the waterproof notebook was abandoned in favour of the little recorder, which worked well under wet, windy conditions. The sun broke through at times and the whole place was looking grand as wetlands in winter can.
“There wasn’t a feather of a Dabchick nor yet a Bittern to be seen, so we’ll go looking in other haunts. It is possible they haven’t read the books and aren’t breeding yet, but it has been a mild winter.
“What we did see or hear in the space of 2 hours 10 minutes, not counting the walk along the road back to the car was, here in random order.”
Black swan 135,
Mallard X Grey 26, (possibly a couple of Shovellers among the tussocks at the sheds pond, but I think they prefer Boggy Pond)
All up16 species were seen by this intrepid pair, who also had an enjoyable lunch and excellent company in beautiful surroundings.
“Who could ask for more?” said Robin.
