By Don Farmer
Feral cats have been blamed as a major reason why a colony of endangered Caspian terns on Onoke Spit have failed to breed successfully.
Friends of Onoke Spit chairman Dougal MacKenzie said that after years of speculating what was disturbing the breeding colony on the spit it had now been established that feral cats were to blame.
“The spit is a significant breeding site for these native birds but they have not bred successfully for several years,” he said.
This breeding season cameras supplied by Greater Wellington Regional Council and the Department of Conservation were set up close to where the birds had settled for nesting at the eastern end of the spit.
A week ago the camera cards were retrieved and images revealed feral cats prowling at night had been upsetting the terns, causing them to abandon nests.
“There has been a regular trapping programme operating along the length of the spit for about six years now but these cats are still the major predator here.
“The answer may be to use alternative forms of predator control,” Mr MacKenzie said.
He said feral cats were extremely clever and could become trap-shy over time.
“We now have the evidence as to why these beautiful birds are not breeding successfully and it may be too late for this year.
“Now we need to target this pest in particular to make sure the birds have a better chance to breed next season,” he said.
Mr MacKenzie’s call for cat owners to show more responsibility by ensuring pets were not allowed to roam free or produce unwanted kittens has been backed up by bird expert Joanna McVeagh.
Ms McVeagh, who is also a Friend of Onoke Spit and a member of Forest and Bird, is urging Wairarapa people to think seriously about how to protect birds.
She backs calls for pet cats to be de-sexed, saying the dumping of unwanted kittens – particularly into the countryside – was doing great damage.
It is also time people got over the notion that hedgehogs are “cute.”
Ms McVeagh said hedgehogs and rats were also a problem on the spit and elsewhere.
“They are really just rats with prickles, wiping out birds eggs and killing lizards,” she said.
Hedgehogs are also laden with fleas and suspected of being TB carriers.
Apart from the tern colony Wairarapa has been home to the critically endangered black billed gull, native to New Zealand, which has had a tough time in recent months.
A colony of the gulls that had set up home on a gravel bank created on an island in the middle of Henley Lake which had been reconfigured have abandoned it.
Rats have been trapped on the island and it has become weed infested, but Ms McVeagh said the birds left weeks before the weeds had taken over.
There had been a lakeshore colony on the Tauherenikau River delta which had fledged chicks but huge storms in November and high lake levels had caused that congregation to also pull up stakes and move out.
Black billed gulls are the most endangered gull species in the world and favour river habitat, particularly gravel islands in the middle of rivers where they have a clear line of sight to guard against predators.
“If river beds become overgrown with things like lupins they won’t stay because it hinders their line of sight, they can’t deal with vegetation,” Ms McVeagh said.
On Friday a colony of black billed gulls, with chicks, was discovered at a spot along the Ruamahanga River.
Because the birds are not banded it is not known for sure where they had originated, but they could be an amalgam of birds from both the Henley Lake colony and the lakeshore colony.
