Two organisations are teaming up to keep hunters happy and poultry healthy.
Fish & Game New Zealand and the Ministry of Primary Industries combine annually at duck-banding time. Fish & Game monitors populations for hunters, and the ministry tests for bird flu.
Two sites are monitored in Hawke's Bay, using two tonnes of maize for bait, said Fish & Game regional manager Peter McIntosh while he was banding birds last week.
"We set up these traps over a period of three weeks and you slowly build the amount of maize. On Monday we closed up the traps so they couldn't get out and on Tuesday we banded about 400," McIntosh said.
When Hawke's Bay Today recently visited Lake Rotokare, near Taradale, there were just as many ducks, but some had failed the IQ test, returning to be caught again.
The bands have numbers on them noting when and where the bird was banded, and its age.
Hunters retain the bands after passing on details of where and when the bird was shot.
"All that information helps us manage the population," McIntosh said. "Guys collect the bands like trophies."
The adult-to-juvenile ratio recorded at banding shows how successful the previous breeding season was.
A wet spring brought more food, making it a successful breeding season.
After banding, the birds were handed to ministry senior veterinary scientist Wlodek Stanislawek, who monitored the ducks for strains of avian flu, which can kill people. Samples are collected from the ducks' mouths and backsides.
"We have been looking since 2004, when there were flu outbreaks overseas," said Stanislawek.
In the past 10 years hundreds of deaths worldwide from avian flu have resulted from bird-to-human infection, and it's possible that the virus will mutate into a form that will spread from person to person, causing a human pandemic with vast loss of life.
If an infectious strain of avian flu was found, poultry industry aviaries would be warned to take extra biosecurity precautions.
"We couldn't control it. Obviously, we couldn't kill all the ducks. We could only inform the appropriate people," Stanislawek said.
Paradise ducks so far had produced little sign of bird influenza, but not so the mallard, he said. "The mallard is regarded as a reservoir for influenza throughout the world.
"There are hundreds of viruses found in mallard ducks in New Zealand, but not pathogenic [infectious] strains."
Juveniles were the most likely to be infected.
"We enjoy the hospitality of our colleagues in Fish & Game and appreciate their help. Without it, it would be difficult for us to collect samples, so they are making a huge contribution," he said.
"They would also play a major role in an outbreak situation by assisting with trapping."
He said the sampling was a welcome break from working in the ministry's Upper Hutt laboratory.
"Unfortunately, we are not often in this natural environment. It is pure pleasure."