A SENIOR wildlife ranger says it is impossible to determine the sex of two crocodiles living in the upper reaches of the Mary River, north of Gympie, without physically checking the creatures.
Ranger Greg O'Neill said although there was a general size difference between males and females, the size of a crocodile depended on various factors.
The only way to know the sex was to physically check as a male's penis was often hidden inside his cloaca.
On Thursday, Mr O'Neill was one of two rangers who were able to confirm a second crocodile in the river when they spotted it floating near resident "Mary Croccins" near the Beaver Rock boat ramp.
The new croc is 2.6m long while the other is 3.5m.
"Males are generally larger - an average male may be 3-4m long," Mr O'Neill said.
"It's unusual to get a female over 3m."
Mr O'Neill said they would be setting traps to try and catch the crocodiles for relocation as per the Department of Environmental and Heritage Protection crocodile management policy.
The policy states that any crocs south of the Boyne River near Gladstone will be targeted for removal to a crocodile farm or zoo.
He said both crocodiles were displaying good behaviour.
"These crocs aren't demonstrating aggressive behaviour, which is what we want.
"But residents still need to be croc-wise."
Crocodile sightings should be reported to EHP on 1300 130 372.
- Male crocodiles average 3-4m long; females average 3m
- Males and females can be difficult to tell apart because the male's penis often stays hidden inside his cloaca
- 'Croc country' typically reaches only as far south as the Boyne River