Conservation workers were horrified to see graphic photos of pūteketeke chicks being hunted and eaten alive by mallard ducks.
Three mallard ducks have now been euthanised following the unusual behaviour in in Lake Alexandrina, just south of Lake Takapō/Tekapo.
Department of Conservation rangers in Twizel were alarmed when a concerned person sent in photos of the ducks hunting and killing the freshly hatched chicks.
The pūteketeke (Australasian crested grebe) hit global headlines when comedian John Oliver successfully campaigned for the Australasian crested grebe to win the Forest & Bird, Bird of the Century crown in 2023.
Doc principal biodiversity ranger Dean Nelson says they were horrified as it was unusual for ducks to prey on other birds.
“Mallard ducks usually eat plant material, with a little bit of protein from insects and snails during the breeding season.
“It was shocking to see them eating pūteketeke chicks. We went out there straight away and I observed three mallard ducks in the outlet creek where the grebe nests are.
“They were actively scoping out the pūteketeke nests to see if they had chicks.
“The adult pūteketeke didn’t see the danger as they don’t perceive the ducks as a threat.”
This duck behaviour was unknown to Doc experts, and there was a concern that it would spread, as ducks learnt from each other, Mr Nelson said.
“There was a case which was referenced in a research paper from a Cambridge University scientist describing how a group of mallard ducks were attacking and eating the chicks of two common bird species in Romania in 2017.
“It claimed this was a world first and the ducks may have been searching for a source of protein before laying eggs and nesting.”
Last December campers and boaties around the popular Lake Benmore shoreline in Canterbury were asked to look out for pūteketeke over the summer holidays after reports of nests being disturbed at the Ōhau C campground.
Many nests were adjacent to the boat ramp and spread out around the lakeshore.
The pūteketeke colony has had 40 to 50 nests each year for the last five breeding seasons and birds have raised their young much later than usual in the outlet creek next to Lake Alexandrina. The ‘colonial’ style of nesting so close together makes them easy prey for predators.
Doc caught and humanely euthanised the three offending ducks and were today to check that no other mallard ducks have learnt the behaviour.
Anyone who sees sick, injured or at-risk native wildlife could ring 0800 DOC HOT.
– Allied Media