After many years birthing foals on a Northern Territory cattle station, an elderly horse called Crystal has started rearing a more unusual type of offspring — orphaned calves.

Crystal's latest adoptee is a five-month-old Brahman calf called Cooper that lost its mother at birth.

Crystal and Cooper spend much of their days and nights together at Mount Bundy station, with the calf at times suckling on the mare's teats, despite a lack of milk being produced.

Mount Bundy station's bemused co-owner Sue Witham described the unlikely suckling relationship as "a bit wrong" to watch.

But she also said the two animals were probably just doing what felt natural.

"I'd say she's just missing having foals and he's missing having a mum. The two have come together," Ms Witham said.

Crystal the horse and Cooper the calf sleep together in the stables and spend most of their day together. ( ABC News: Jano Gibson )

How a former broodmare took to calves

Ms Witham and her husband brought Crystal to their station about a decade ago to work as a broodmare — a female horse used for breeding — and she gave birth to six foals over the years.



"She was one of those good old mums that do everything for their foals and raise them really well. I'm proud of her," Ms Witham said.

Last year, after Crystal grew too old to give birth again, Ms Witham noticed the mare had formed a close bond with a poddy — an orphaned calf.

After the calf was weaned off the bottle, Crystal let it suckle on her teats.

"The first time she did it, I definitely thought she was going senile, I thought: 'What are you doing?'," Ms Witham said.

Ms Witham loves animals and says they are "more attuned to things" than most people give them credit for. ( 105.7 ABC Darwin: Emilia Terzon )

The duo were also a bizarre sight for the campers and grey nomads who visit Mount Bundy, a primarily tourist-focused cattle station about an hour's drive south of Darwin.

"We had many a bug-eyed tourist going: 'Is that a calf and is that a horse?'," Ms Witham said.

"But [Crystal] seemed to be quite enjoying the whole situation, so I thought, so be it. Let's just let it happen."

The pattern was repeated this calving season after Cooper was found alone and without a mother in a paddock.

He was brought to the stables to be fed by bottle for three months.

"When she started doing it again this year, we thought she's definitely missing having babies," Ms Witham said.

"They've obviously formed a bond in the night time, whilst being locked in the stables.

"Crystal's decided to adopt him. She has no milk but she thinks she should be doing the right thing and feeding him."

An unlikely and mostly harmonious relationship

Crystal and Cooper sleep together at night and spend most of their days together underneath trees or near the horse's hay bales.

Occasionally they go their own ways.

"Every now and then, Crystal has a grasp of reality and goes: 'Hang on a minute, that's a calf'," Ms Witham said.

"So she bites him, she kicks him, and sends him away. Then the next minute, she's waiting for him and calling for him: 'Where are you, Cooper?'"

"Crystal has no milk but she thinks she should be doing the right thing and feeding him," Ms Witham said. ( 105.7 ABC Darwin: Emilia Terzon )

Ms Witham said Crystal's behaviour with calves was indicative of the maternal nature of many animals.

"When you spend a lot of time with animals, you pick up the intricacies of life as an animal. They're more attuned to things than we realise," she said.

"They've got a fair drive to reproduce [and] a calf wants a mother. It's kind of normal.

"We have some odd sorts [at Mount Bundy station] and get some fairly good bonds between buffaloes, horses and cows. But this is the first time I've ever seen this much connection."

University of Queensland animal behaviourist Anne Goldizen told the ABC that Crystal and Cooper's behaviour was not entirely unusual for animals in captivity.

"You could find this sort of behaviour in zoos and animals in captivity," Associate Professor Goldizen said.

"Females like to look after babies and they can accept other animals."