Karoro - bird on a mire

Recent plans to cull a few black-backed gulls at the Green Island landfill have ruffled some feathers.

There had not been a single vote for the black-backed gull in Forest and Bird's Bird of the Year competition, by the end of September.

The closest relative of the gull to feature in the competition is the skua, which had received just 11 votes out of more than 4500 at the same stage.

The description of the skua on the competition website perhaps provides an explanation for its poor showing: "According to Collins Guide to the Birds of NZ, skuas have `hooked beaks and piratical habits', attack gulls and other seabirds and eat offal, which makes them possibly the underbird in Bird of the Year".

Well, ditto the black-backed gull, according to many of those who have observed its habits.

On the other hand, when the prospect arose recently of a few of the birds being offed at the landfill, there was something of a hue and cry.

Not precisely the hue and cry ascribed to the gull, which goes "uhuh, eeah - ha-ha-ha-ha-ha" or "kaloo, kaloo, kloo, kloo, kloo, kloo", according to the Tiritiri Matangi website.

But voices were raised in protest.

"What utterly disgusting and unacceptable behaviour in this day and age," wrote one Otago Daily Times correspondent of the plans to cull the gulls.

The upshot was that the programme of offing the gulls was stopped.

It was off.

Bird-lovers, no doubt, gave a sigh of relief.

Or perhaps a squawk, a "uhuh, eeah".

But not all of them.

Not all of the bird-lovers of Clariton Ave, for example, were quite as delighted about the reprieve.

One such is John Neill, who knows a thing or two about the gulls and particularly the landfill gulls, because Mr Neill has lived the larger part of his life within a few wing-beats of the city tip.

His present address, of 18 years, abuts the landfill, which he says is extremely well-managed and a model neighbour.

"I have grown up around it.

I know when it's being looked after properly, when it is being managed properly or not."

And it is, he says.

Except for the gulls.

"It's like a big black funnel going up into the sky," he says of the way in which the gulls take to the sky whenever disturbed at the landfill, or when they leave at the day's end to return to their roosts.

"All of a sudden you have thousands of seagulls flying over your house and the issues that accompany that."

Mr Neill concedes that it can be an impressive sight, but the attendant noise undermines the experience.

"It would be almost like a chainsaw or a motormower going.

It is really loud," he says.

Other issues raised in association with the gulls include the part they play in redistributing rubbish from the landfill around the neighbourhood.

"It is quite a nuisance," Mr Neill says of it all.

This is a man not given to overstatement or indeed overreaction.

He is not calling for wholesale slaughter.

He likes birds: the pukeko at the bottom end of his garden, the sparrows roosting in his carport spouting.

"They aren't trying to destroy the population of black-backed gulls," he says of landfill contractor Delta's controversial efforts.

"It is not wholesale destruction.

They are trying to deter the birds from being there in the first place."

The canny birds would soon catch on, he says, when they spotted one or two of their number lying unusually inert about the dump.

That is an approach with which Department of Conservation Southland Conservancy programme manager biodiversity Jessyca Bernard is familiar.

For Ms Bernard has been involved in offing the seabirds in a couple of spots in Southland where their numbers were causing a problem.

Yes, the keepers of our native flora and fauna also cull the native gulls from time to time.

And when they do so they use the same method proposed for the Green Island landfill - the poison alphachloralose.

It's a poison used to control bird numbers - including rooks, pigeons and sparrows - around the world.

It slows the birds' metabolism to the point where they drop from their perches with hypothermia.

Or, as Ms Bernard has more often observed it, expire quietly in their nests.

In the case of the Green Island landfill, the plan was to scoop up any non-target species and warm them back good health by a heater.

The two spots where the government department has used poison in Southland are Tihaka Island and the Pukerau Red Tussock Scientific Reserve, in both cases because black-backed gulls were having a deleterious effect on the flora.

"In both places, the gulls have colonised and started to breed there and in the last few years their populations have had a huge impact," Ms Bernard says.

"The gulls clear the earth to make nesting sites and modify the soil structure with the nutrients they provide with their poop."

As a result, weeds were invading the red tussock reserve at Pukerau and the flora on the small island of Tihaka was being threatened.

"This flora hosts insect life and lizards that live in these native grasses."

So despite the fact that the gulls too are native, they had to go.

"At Tihaka and Pukerau there are some things that rank a bit higher than they do," Ms Bernard says, though conceding that such a weighing of priorities is not easy.

But after all, the black-backed gull is hardly a threatened species.

"It is safe to say the total number [of gulls] is extremely healthy.

Everything is working well for them.

They are benefitting from human population," Ms Bernard says.

This year there probably will not be any poisoning at Tihaka, as Ms Bernard says the gulls seem to have twigged to the danger and are steering clear of the island.

Those at Pukerau will probably get another dose.

While dedicated bird-lovers might question the department's actions, it is on firm legal ground.

Black-backed gulls were dropped from the protected schedules of the Wildlife Act 1953 some years ago.

They now sit in schedule five alongside the stoat, feral geese and mice.

ELSEWHERE in Southland, the gulls have been dealt with by methods more often associated with such offshore interlopers.

At the Invercargill City Council's old estuary dump, for example.

The Invercargill council has in recent times moved its landfill to Winton, far from the coast and the gull problems of the previous estuary locale.

There it took a solidly southern approach.

"We shot hundreds of them," says roading and solid waste manager Tom Greenwood.

He has considerable sympathy for the Dunedin landfill's neighbours.

"They are a dirty bird," he says of his old nemesis with some feeling.

"Once they are established at a landfill and are used to feeding there, then it is very, very hard to control them."

Mr Greenwood took up arms himself because the Invercargill landfill gulls had identified the threat posed by the on-site manager and took to their heels (or at least the skies) when they saw him coming - often leaving a token of their regard on his car.

"They would bomb him.

You wouldn't believe it.

They knew him.

It was quite hilarious."

Mr Greenwood could get closer.

"I had a gun licence as well and if I was down there we would get the gun out.

"It was a never-ending battle."

At Green Island the built-up areas are a bit close for liberal use of firearms.

So since the kibosh was put on alphachloralose, DCC solid waste manager Ian Featherston says they have been looking at other options.

"We have just modified the landfill operation at the mo, basically putting on more cover to limit the exposure of food sources."

They are also talking to an ornithologist about a survey of bird numbers and bird varieties in and around the landfill, to get a better handle on how the local ecosystem is working.

"There was some anecdotal evidence that there are more varieties of birds out there since we have controlled the black-backed gulls with poisoning in the past," Mr Featherston says.

Clariton Ave favourite, the Pukeko, seems to be one species that benefits.

Mr Neill would like to see rather more action on the matter and expresses little patience, for a plainly patient man, with the letter-writing bird-lovers of leafy Belleknowes and Opoho.

"What would they know?" he asks.

He has little more time for those on the council who he believes fell into line a little too quickly on the matter of the poisoning programme.

"It is just expediency," he says.

"Someone blued about it and have got it stopped and they are looking like the hero.

"I think it needed to be looked into a wee bit more deeply."

The Ornithological Society of New Zealand recently started a count of all bird species in Otago Harbour.

Otago regional representative Mary Thompson said all species would be counted once a month for a year.

The survey was last conducted in 1989.

The bird Of New Zealand's gull species, black-blacked gulls (or karoro) are the largest, at 60cm long. Males weigh more than 1kg and females about 850g.

Adults have white bodies, black wings, and yellow bills and legs.

Its manners

Black-backed gulls have been recorded as threatening rare birds, such as the New Zealand dotterel, little blue penguin, and some terns and petrels by predating on eggs and chicks.

They can also attack newborn lambs.

They were found to spread Salmonella Brandenburg, an infection causing spontaneous abortions in sheep and cattle, which the gulls got by eating dead fetuses with the disease.

Black-backed gulls also feed on fish, shellfish, offal and carcasses, and fruit.

They are often seen in ploughed fields taking worms and grubs.

The gulls often return to favourite feeding spots.

Another problem

According to the Government's Te Ara encylcopedia website, black-backed gulls living near airports can get sucked into a plane's engine, damaging the craft or bringing it down.

In a two and a-half-year period at Wellington Airport during the 1990s, 74 birds were hit and there 362 were near-misses.

Of these, 63% were black-backed gulls.

Gulls are now prevented from nesting near Wellington Airport, and the Department of Conservation has reduced the number of nests on nearby islands in Wellington's harbour.

Injecting eggs with formaldehyde is one way of controlling numbers.

 

 

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