The peek-a-boo bittern by Nicola Toki
after an interview with Peter Langlands - Bittern Researcher 12 July 2012
Published on www.stuff.co.nz
Hands up who has been lucky enough to see a bittern in New Zealand? (Puts her hands down - with accompanying sad face.)
New Zealand is a stronghold for the makatu or Australasian bittern, but even so, we only have around a thousand left. This is exacerbated by the fragmentation of their habitat and the way they are scattered across the landscape, meaning it's harder for them to find each other across wide areas, and easier for tiny populations of them to get knocked out by chance events or predators.
Bitterns are masters of disguise. They have beautifully marked feathers that match their wetland reedy surroundings, and when in danger, they engage in a rather bizarre tactic of adopting a "freeze" position - standing straight and still in the raupo or reeds, pointing their bill to the sky and simply disappearing into the landscape. A friend of mine recently told me that she spent a couple of hours crouched in a wetland on the West Coast hoping to see a bittern, and when she gave up and moved away, one flew up out of the reeds next to her. The strong legs of the bittern mean they eject themselves out of the reeds like a jack-in-the-box so I imagine she got quite a fright!
If you haven't seen a bittern, you may have heard one. Like the kakapo, they "boom". The males blow themselves up like a bullfrog and make a low-resonance booming noise that can apparently be heard for up to two kilometres. Given the bittern's incredible camouflage, the booming is often the only way to know that they are present in an area. If you're keen to find out if you have bitterns in your 'hood, listening out at dawn or dusk from now until November is a good way to find out.
Bitterns are the apex predator of the wetland, so if your wetland has bitterns it's a good sign you have a healthy, well-functioning ecosystem. The bitterns eat young eels, fish, frogs, freshwater crayfish and insects.
Where did all the bitterns go? In the space of 150 years, New Zealand has managed to drain and destroy 90 per cent of our wetlands, which are home to a huge range of native wildlife, including bitterns. Add in the mix the impact of predators and the odd roadkill death and you've got a recipe for a declining population.
It's not all bad news though. Occasionally people give bitterns a helping hand, as in the case of Bitty the bittern, who spent a week or so in the Whangarei Bird Rescue Centre, who was fed, housed and then released back into a wetland to get on with his life. Or the story of the young bittern nestling who wandered into a chookhouse and spent three months living alongside his chook "mates".