She's not exactly what you'd expect from the front line of New Zealand's defence against millions of insatiable killers.
She weighs just over 6kg, stands not quite 30cm tall at the shoulder, has an irrepressibly waggy tail, and she's more cuddly than athletic.
Even her name — Gadget — is hardly likely to strike fear into the hearts of her enemies.
Yet those small furry shoulders bear a heavy responsibility, because she's part of a crack team of conservation dogs tasked with sniffing out rats, stoats, feral cats and other introduced predators.
Without Gadget and her friends, nowhere — not even the most remote offshore islands — would be safe for New Zealand's unique native species.
Gadget's human, Sandy King, says she spotted the Jack Russell-fox terrier cross on Trade Me seven years ago.
Gadget may have been a "neighbourhood special" — the result of an unsanctioned visit by a pooch from another farm — but she had the right breeds to make a good rodent dog.
"I had a look at the pups and at first she seemed the least suitable. She was the runt of the litter with short legs and short fur, but what she lacked in size she made up for in attitude — and that matters more," King says.
The power of a small dog
In December, Gadget joined 18 other conservation dogs as they searched every nook and cranny of the pest-free Ipipiri islands in the eastern Bay of Islands for uninvited guests.
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Becoming a certified pest detection dog took 18 months of intensive training; now she and King run a business called Paws 4 Conservation, which contracts to the Department of Conservation (DoC) for rodent detection services.
The pair are based on Stewart Island, which has all three species of rat found in New Zealand (but, oddly, no mice) while nearby Ulva Island, a wildlife sanctuary, has neither rats nor mice. One of Gadget's responsibilities is to make sure it stays that way.
"If she smells a rat, she has a particular stare and she puts her paw up. And if there's something live in the vicinity she goes completely frantic, digging, searching and sniffing."
Gadget's role goes beyond merely sniffing out unwanted rodents. She is also a canine PR campaigner, reminding New Zealanders about the value of their unique wildlife and the need to be ever-vigilant about pests.
Gadget is, after all, "just one small nose". It's not a war she can win on her own.
Any time the pair travel by ferry between the mainland and Stewart Island, Gadget checks the passengers and their gear for rodent stowaways. Every search is an opportunity to spread the message, as is her popular Facebook page with more than 1000 followers.
"A small, cute dog engages people, then you can talk to them about what you're doing. And because she's small and non-threatening she goes well with children, so we do a lot of school visits. That's the power of a small dog."
10,000 human noses
Fin Buchanan, a senior pest detection dog adviser, says DoC's conservation dog programme has 91 four-legged staff and 74 human handlers.
Some are employed directly by DoC, while others are private contractors or employed by local authorities.
Pest detection dogs are trained to sniff out unwanted predators; species dogs are trained to locate endangered wildlife such as kiwi and kākāpō.
All have one thing in common which makes them such a powerful conservation tool, Buchanan says.
"It's the little black thing on the end of their face. A dog's nose is at least 10,000 times more powerful than a human's."
Even your average domestic pooch has 300 million olfactory receptors compared to a human's 6 million, while the proportion of the canine brain dedicated to analysing smells is 40 times bigger than a human's. Little wonder, then, their noses are so useful.
An annual get-together
Once a year, DoC organises a week-long get-together for its canine employees and their human handlers.
The aim is two-fold, Buchanan says.
"It's an opportunity for all our dog handlers to do a job together because they're scattered right through the country, from Stewart Island to Paihia, and learn from each other. We've got some very new handlers and some who've been doing it for a long time."
The other purpose is to give the host area — in this case the Bay of Islands, the year before it was the Mercury Islands off Coromandel — a thorough check-over for pests.
Between trips to the Ipipiri islands, where pests were eradicated in 2009 as part of Project Island Song, the dogs sniffed around in mainland forests and carried out biosecurity checks at every wharf and marina in the Bay.
No pests were detected on the islands, a result Buchanan describes as "very reassuring", but the picture wasn't quite as rosy on the mainland.
Feral cat detector dogs found 30 cat scats — that's a polite word for poo — in Opua State Forest, in an area where conservation group Bay Bush Action plans to expand its pest-trapping efforts, while a mustelid detection dog caught a whiff of stoat or weasel on the shoreline at Waitangi Golf Club, a stone's throw from the Treaty Grounds.
Buchanan says the dogs are always muzzled in wildlife areas. Their job is not to kill pests but to let their handlers know if they are present.
"If the dogs indicate on an island our job is virtually done. We say, 'guys, you've got a problem'. Then local DoC staff or contractors go in with traps or, in the worst case scenario, they may have to put bait out."
Before the annual get-togethers started, pest checks targeted a single species with one dog and handler sweeping an island at a time.
"In those days, a rodent dog could have told us there's no rats on the island but left a stoat undetected and feasting on native birds for maybe months until a mustelid detection dog made its visit."
That changed just over three years ago when Kiwibank came on board as a sponsor of the Conservation Dog Programme.
The extra cash had "raised the game" and the programme now boasts a full-time manager, two senior advisers and four full-time handler teams, an in-schools education programme and has the ability to bring people and dogs together for on-the-job training.
The planet's rarest bird
One of the newest pest detection dogs at the Russell get-together also has one of the most important jobs.
Moki, a Jack Russell, and his handler Kerri Moir are based in the Chatham Islands, where they help look after some of New Zealand's rarest birds.
Moki is the only pest detection dog in the country trained exclusively to sniff out rats. He has no interest in other rodents. His nose won't even twitch for a mouse.
Twice a year the pair head to Pitt Island, the smaller of the Chathams' two inhabited islands, which has a grand total of 50 humans, an unknown number of mice and zero rats.
It's essential that Pitt's rat population stays at zero. If a rat did manage to stow away on a boat to Pitt Island, it could then swim the short distance to Rangatira or Mangere islands, and that would be an ecological disaster.
Those two islands are home to unique species such as the Chatham Islands black robin, which once had the unenviable title of the world's rarest bird. In 1980, only five remained, of which just one was a fertile female. A huge effort brought the robins back from the brink but they remain vulnerable.
Twice a year, Moir and Moki, who are employed by Environment Canterbury and contracted to the Chatham Islands Council, carry out a sweep of Pitt Island to make sure it's still rat-free.
Moir said the get-together at Russell's Orongo Bay Holiday Park was "amazing".
"It's a chance to get together with all the other dog handlers and learn new things. Moki and I have only been in this game for 18 months but everyone imparts a bit of wisdom."
Not all detection dogs are trained to sniff out pest animals. The 19 keen noses visiting Russell belonged to rodent dogs, cat dogs, mustelid dogs, plague skink dogs, an Argentine ant dog – and one weed dog.
[Before you ask, not that kind of weed. Though that could come in useful in Northland...]
Wink was bred as a heading dog on a Southland farm but was still a puppy when an untreated ulcer cost him the sight in one eye.
"So the farmer gave him to me," Invercargill dog handler John Taylor says.
"He gave away the best dog he ever had."
Now the one-eyed Wink is one of just three weed-sniffing dogs in New Zealand. His specialty is spartina, an invasive grass that grows in estuaries, trapping silt and robbing fish and birds of habitat.
Thanks in part to Wink and Taylor's teamwork, spartina is now all but eradicated in the South Island. The main problem areas now are the Firth of Thames and Kaipara Harbour.
Pests don't have to be big or have sharp teeth to threaten Aotearoa's wildlife.
DoC ranger Adeline Bosman has trained Vito, a Welsh springer spaniel, to sniff out Argentine ants, a predator which makes up for its lack of size with aggression and sheer numbers.
Bosman says a special kind of nose is required to locate such small targets. Springer spaniels make superb sniffer dogs, and the Welsh variety's temperament makes it a better fit for the job than the more intense English springer spaniel.
Bosman and Vito started out on Mercury Island, off Coromandel Peninsula, but have more recently been employed to work on the islands of Auckland's Hauraki Gulf.
"Argentine ants breed to prolific numbers and form vast super-colonies," Bosman says.
"They're multi-queened so they're not easy to eradicate and they displace all other ants. They'll eat lizards, other insects, and even small birds. They're very aggressive. It's the sheer numbers."
The Argentine invaders are known to be in Northland but Vito's fortnight in the Bay of Islands came up blank. Bosman did see lots of native ants on the islands, which she says is a good sign.
The key to keeping the ants off the islands is for everyone to check their boats, bags and gear before heading out.
"If everybody does their bit it would really help the islands. They're such a treasure."
While canine nose power is essential when it comes to making a successful detection dog, it isn't the most important thing.
The main ingredient of the Conservation Dog Programme is the relationship between dog and handler.
Like all the teams at Russell, Bosman and Vito are just about inseparable. When she first got Vito she took a month off work to dedicate herself fulltime to bonding with him.
"We're such a close team. He's my best mate," she says.