The search team looking for missing toddler Ruben Scott have been advised by experts that the likelihood of him surviving in current conditions has slipped away.
Ruben has been missing since late Tuesday afternoon when he disappeared from a remote cattle station on Queensland's Cape York Peninsula.
Paediatric experts have counselled the family and search crews that the likelihood of the two-year-old surviving in the harsh conditions has passed.
"It's with regret that last night I had to sit with the family and advise them that the survivability of their son and grandson has now passed," Cape Patrol Inspector Mark Henderson said.
"That won't stop our efforts, we've had some 1700 square kilometres, 450,000 square acres to search. It's been a very hard task and we've given it our best.
"But paediatric experts now tell us that survivability has passed."
Police have scaled back their use of helicopters and other aircraft, and are focusing their searches on the ground and water, according to reports.
Mr Henderson said the search would not stop, and the team would continue trying to find Ruben, to bring closure for the family.
Search efforts resumed today. Helicopters and heat-seeking drones have been aiding the search, with search crews scouring bushland on foot, horseback and motorbikes.
Mr Henderson said yesterday that search crews were determined to find the little boy, but with three nights having passed, the search was becoming desperate.
"I guess it is coming to that time where the fears that we have for this young fellow start to become grave," he said on Thursday.
The search team includes the help of concerned neighbours, and police divers searching waterways.
The cattle station backs on to a lagoon and the Mitchell River, east of Kowanyama, on the western side of Cape York Peninsula. It is a known crocodile habitat.
Ruben's mother Natasha Scott said she last saw her son about 5.45pm on Tuesday. In a social media post, she said she was doing her best to hold herself together.
"I have every person that can help helping to find him. I understand all you guys are shocked and worried but please, try to hold back from messaging me," she wrote on Facebook.
"I'm trying to organise heaps of things to help find him and am trying to hold myself together. I thank and appreciate all you guys are doing for us, the shares help."