More than 100 venomous red-bellied black snakes have been dragged from a woodpile in a Sydney backyard in an alarming, and rather unique find.

The disturbing discovery came after the residents of a home in the outer-western suburb of Horsley Park noticed the reptiles disappearing into their woodpile so called in snake-catchers.

“We were called to remove some red-bellied black snakes sighted on a mulch pile in the backyard of a property in Horsley Park,” Reptile Relocation Sydney posted on Facebook.

“Over the last two weeks, the home-owners had sighted a couple of red-bellies disappearing into and out of the mulch pile, and at this time of year, it can be common for some females to congregate and share the same birthing site.”

Reptile Relocation Sydney owner Cory Kerewaro said his team was called in after the home-owners’ dog was bitten.

Home-owner David Stein said he was horrified by the discovery.

“By the time I got my camera, they went into the pile of mulch,” he told News.com.au.

“It was terrifying.”

The house’s residents spotted several of the snakes disappearing into a wood pile. Photo: Reptile Relocation Sydney

The experts arrived in Horsley Park, expecting to find four snakes. Instead, they pulled out more than 40.

“Within a few minutes, we knew this was going to be unusual,” snake-catcher Dylan (whose surname has not been given) said on Facebook.

“Snake after snake, they just kept being uncovered.”

Disturbingly, the tally grew even more when they did a recount shortly before leaving the property.

“We checked the bags … and two of them had given birth and it brought the number up to around 70,” Kerewaro told the ABC.

“By the time we got them back home to do a proper count and to check over them and stuff like that, the others [had given] birth and [there] ended up being 102 in total.”

There were so many snakes on the property that the snake-catching team enlisted the help of the home owners to nab them all.

“They ended up actually chugging on a pair of boots and long pants and help rake through the pile,” he said.

“[It] took three hours in total to get through and get it all. If they didn’t help, we probably would have called it a day and [gone] back the next day to keep going.

“Long story short, we went for four adults and came out with 102 snakes in total – 97 newborn red-bellies and five adults.”

Red-bellied black snakes are common in eastern NSW and Victoria, according to the Australian Museum. They are venomous but – like most snakes – not aggressive unless they feel in danger or threatened.

The females commonly gather in small groups towards the end of the pregnancies, for greater protection against predators.

Despite that, Kerewaro said it was the “most venomous snakes in the one spot at the one time” he’d heard of.

“In nature it’d be really common, it’s just that we physically don’t see it — we’re just the lucky ones that come across it,” he said.

Kerewaro said NSW wildlife authorities had given permission to “go deep in the national park where no one is going to be” to release the slithery haul.

“They’re not bad as long as people are snake aware and they don’t mess with them,” he said.

“If it’s up around the house and you do want to remove them … call a catcher and get some advice.”