Sally, from the Kapiti Coast, is part of an "underground" network of possum rescuers. She currently has 10 of them in her care.

Little Batman is fighting for his life.

The baby possum struggles to feed after the soft roof of his mouth when damaged when he was ripped from his mother's pouch by a hunter.

Too young to regulate his body temperature, the six-week-old is fed through a tube by his carer, who tends to his every need, desperately trying to keep him alive.

ROBERT KITCHIN/STUFF Little Batman is critically ill. He has to be fed with a tube because his mouth was damaged when he was ripped from his mother's pouch by a hunter.

She may be breaking the law by doing so.

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Sally (not her real name) is part of an underground network across the country, dedicated to saving the lives of animals that are, to most Kiwis, one of our most hated pests.

She has rescued about 150 possums, and currently has 10 of them in her care.

Threats from the public, and fear of authorities removing their pets, kept most rescuers "underground", she said.

"Some people hate them [possums] so much they threaten to find out where you live and kill them."

NGA MANU IMAGES A possum tucks into a kereru egg.

Possums, first introduced from Australia in 1837 to establish a fur trade, are known to spread tuberculosis, and decimate native plants and animals. They have no natural predators in New Zealand, and now number about 47 million.

Babies, or joeys, are born the size of jellybeans. Most of those that find their way to Sally and her sympathisers come from hunters who have killed the mother only to find a baby in her pouch, or from people who stop to check the pouches of possums killed on the roads.

Sick and orphaned possums are then transported around the country by the network of rescuers.

ROBERT KITCHIN/STUFF Dawn the baby possum is four months old and thriving.

One Kapiti rescuer said possums made "loving and loyal" pets that more people should take the time to understand.

She had owned three over the years and, although she kept them inside, felt there was little harm in releasing them if they were de-sexed.

A Horowhenua woman, owner of six possums, said getting vets to de-sex the animals would ensure that they died out.

ROBERT KITCHIN/STUFF Possums were introduced to New Zealand in 1837.

"Just like the feral cat populations. If they're not breeding, then there's no harm."

The law on keeping possums is confusing. The Department of Conservation (DOC) says they cannot be kept without a permit. But the Ministry for Primary Industries (MPI) says they can, as long as the regional council allows it.

"We're not the possum police," DOC spokesman Herb Alexander said. "We've got better things to do than creep around backyards looking for pet possums.

ROBERT KITCHIN/STUFF Baby possums, or joeys, are born the size of jellybeans. Batman is just starting to get fur.

"We don't get anal about enforcing the law, but we don't encourage it."

Permits for possum-keeping were not handed out by the department, unless it was for the purposes of research – "Basically for people who are researching how to kill them."

An MPI spokesman said the Biosecurity Act let people keep a pet possum without a permit as long as their regional council allowed it.

ROBERT KITCHIN/STUFF Pixie is three years old and lives in a cage at her rescuer's house.

"There are, however, strict criteria around breeding possums and putting them on public display."

According to Greater Wellington Regional Council, possums can be kept as pets, but cannot be released, bred or sold.

PESTS OR PETS?

A Federated Farmers pest management spokesman said pet possums were not a big concern.

"There are apparently 47.6 million possums in NZ – a portion of that number kept as pets isn't going to make a difference.

"The reality is we can't do much about people who choose to have possums as pets."

Forest & Bird spokesman Kevin Hackwell​ said it was wishful thinking if owners thought their pet possums wouldn't harm the environment.

"The reality is that, if they want to look after the environment, they should be humanely euthanising the young."

SAFE director of research and education Andrew Knight said the loss of native birds was tragic, but the biggest threat to biodiversity came from people, not possums.

"It is important to remember that possums are simply trying to fulfil their natural urges to survive and reproduce.

"We do not support killing some animals to save others."

HELLO POSSUMS: A BRIEF HISTORY

1837 - Introduced from Australia to establish a fur trade

1858 - First population established in Southland.

1921 - Government bans more liberations, but hunters continue to release them.

1930 - Possums can be found in 450 locations.

1946 - Possums declared a national pest.

1951 - Bounty scheme introduced to curb population growth.

1980 - Possums had colonised 91 per cent of the country.

1981 - The peak of the fur trade, with 3.2m skins exported.

1993 - Evidence found of possums eating birds' eggs and chicks.

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