The Brahman cattle are thought to have been living on Snapper Island for several months. ( Supplied: Jayne Miller )
A FNQ resident spotted two Brahman cattle on Snapper Island, 3km off the Daintree coast, on Friday.
She believed the cows may have been swept out to sea during a flood and appeared to be thriving.
Queensland's environment department said it was trying to track down the animals' owners.
Two cows have made a life for themselves on a tropical island in Far North Queensland, several months after a major flood may have swept them from the mainland.
Wonga Beach resident Jayne Miller alerted rangers after spotting the two Brahmans on Snapper Island, about 3 kilometres from the mouth of the Daintree River, during a family day trip last Friday.
Ms Miller believed the cattle had been washed out to sea when the river flooded in March, sweeping away boats, a pontoon and the car ferry.
Snapper Island, within the Hope Islands National Park, is a popular destination for camping, fishing and birdwatching.
A regular visitor to the island, Ms Miller said the first sign of the bovines was a frightening, loud noise "crashing down the hill" as she sat on the island's southern shores.
"Gave me quite a fright and all I could think of was that it was a pig or a human coming from the other side of the island and then it just disappeared," she said.
As she was leaving, however, she spotted the "sad little eyes" of a brown Brahman peering at her from the top of a ridge.
Using the supplies she had, Ms Miller headed towards the cow with 4 litres of water and some food when she saw another one emerge from the trees.
"I could see ear tags on them, but I couldn't see their brand," she said.
"We go out there fairly regularly and yet to think that they've been there that whole time and no-one's noticed or heard [them]."
Snapper Island is only a nautical mile south-east of Cape Kimberley. ( Flickr CC BY-NC 2.0 : Shek Graham )
In a statement, Queensland's environment department said it was trying to track down the cows' owners.
Ms Miller said while the cattle appeared healthy, she left water and molasses at the island on Monday.
Despite trying to track the animals for nearly an hour around the 66-hectare island, in the hope of getting a photo of their brands, she didn't spot them again.
She said the cows may be tucked up high in the forest near a freshwater source.
"You could tell by the amount of pooing and trampling down that they're quite successfully eating and drinking up there and fortunately we've had a wet year so there'll be more water and more grass," she said.
Ms Miller said the cattle had probably survived a flood, crocodile-inhabited waters and seven months marooned on an island but extracting them from the remote location may be difficult.
Snapper Island is a popular camping, fishing and birdwatching destination. ( Supplied: Jayne Miller )
"It sounds like you need a barge-style vessel to retrieve the cows," she said.
"They're not in a readily accessible area. You'd probably need to have a bit of cattle knowledge to lure them to somewhere where you'd be able to retrieve them."
She said it was comforting that the cows had each other for company.
"When there was just one, we felt so sorry for it," Ms Miller said.
"But then when another one came through, I was like, 'Oh, that's so much better'.
