The death of a maned wolf and her two pups due to farmland encroaching on their habitat is an “upsetting and poignant reminder of what could be lost”, says one of the filmmakers behind Planet Earth III.

The latest episode of the BBC nature programme followed the endangered wolves in their natural environment within the Cerrado region in Brazil.

The area is the “richest grassland on Earth” and home to the “thousands of species of plants and animals found nowhere else” including the rare, fruit-eating maned wolf, according to the BBC.

The first ever glimpse inside the den of wild maned wolf, in the Brazilian cerrado (BBC Studios/PA)

Little is known about the creature and so the nature team tasked themselves with filming them, a task made more difficult by their habitat being an area with thick, tall grasses that obscures wildlife.

They collaborated with a group of scientists for more than three years and together tracked the wolves down with drones and gave some of them radio collars to provide more information on the species.

To better understand their behaviour, they devised a system of small remotely controlled cameras which allowed them to film inside the den of a maned wolf for the first time.

The footage helped the team illustrate the challenges the endangered species face due to the natural Cerrado environment being “destroyed” for farming.

After filming ended, the mother maned wolf and two of her three puppies that featured in the programme were found dead on neighbouring farmland having drowned in drainage ditches used to feed the crops, the BBC said.

The first images ever of wild maned wolf puppies playing inside their den (BBC Studios/PA)

Producer and director Kiri Cashell said: “The death of our maned wolf, Nhorinha, and her puppies is truly heart-breaking.

“We spent three years working with scientists to better understand this species, and the footage we were able to capture from inside the den provides such an intimate look into the first few weeks of these puppies’ lives.

“Sadly since filming ended, we have discovered that the mother and two of her puppies fell into drainage ditches which are used to feed the crops of neighbouring farmland. Unable to escape, the wolves drowned.”

Cashell added that this is “not an isolated incident” as a number of other numbers which have been tracked by scientists at Oncafari have been found dead.

She continued: “It’s a really sad representation of what’s going on, and a reflection of the big problem facing the whole species.

“More and more, farmland is encroaching onto the Cerrado. This is a vitally important grassland and some predict it could disappear completely in the next thirty years.

“The death of these maned wolves is an upsetting and poignant reminder of what could be lost.”

Planet Earth III continues on Sunday nights on BBC One