Reptiles
To date, 117 species of reptiles have been recorded in Kakadu and they include Kakadu's largest predators, crocodiles and snakes.
Two species of crocodile occur in Kakadu: the freshwater crocodile (Crocodylus johnstonii) and the estuarine, or saltwater, crocodile (C. porosus). Freshwater crocodiles are easily identified by their narrow snout and a single row of four large 'scutes' (dermal plates) immediately behind the head. Estuarine crocodiles do not have these scutes and their snout is broader. The maximum size for a 'freshie' is three metres, whereas a 'saltie' can exceed six metres. Estuarine crocodiles are most common in tidal rivers, floodplain billabongs and coastal waters but are also found in freshwater billabongs and waterways as far inland as the base of the escarpment.
A variety of reptile species inhabit the park, among them 37 skink species and 36 species of land snakes. Only four of the snakes are considered potentially lethal to humans - the taipan, the death adder, the king brown and the western brown. One of the more unusual snakes found in the park is the file snake. Their valvular nostrils and rough skin for grasping prey are adaptations to a life spent entirely in water.
Waterways are home to water pythons that feed on birds and their eggs. The Oenpelli python, which lives only on the Arnhem Land Plateau and is well known to Aboriginal people, was only discovered by Western scientists in 1976.
There are 11 types of turtle in the park including the northern yellow-faced, northern snapping, sawshelled, long-necked and pig-nosed turtles. 11 species of monitor lizards, also known as goannas, may be seen along road verges, alongside rivers, creeks and billabongs. Depending on their habitat they eat fish, frogs, insects, eggs, birds, small mammals and carrion.
Watch for small dragon lizards and skinks scurrying into the undergrowth along walking tracks. The spectacular frilled-necked lizard hides in the trees through the dry season and appears after the first wet season rains.
The rough knob-tail gecko
Common or notable reptiles
- Arafura file snake Acrochordus arafurae Na-wandak
- Flatback turtle Chelonia depressa Lumbybugan (Limilngan language) factsheet
- Estuarine crocodile Crocodylus porosus Ginga factsheet
- Freshwater crocodile Crocodylus johnstonii Gumugen factsheet
- Frill-necked lizard Chlamydosaurus kingii Narlangak
- Gould's goanna Varanus gouldii Galawan
- Long-necked turtle Chelodina rugusa Al-mangiyi
- Merten's water monitor Varanus mertensi Burarr
- Olive python Liasis olivaceus Alngurruhmanj
- Pig-nosed turtle Carettachelys insculpta Warradjan
- Rough knob-tail gecko Nephrurus asper Belerrk
Turtle surveys on Field Island
Watch the video
photo | Ian Morris
Gardangarl (Field Island) is a critical habitat for flatback turtles and a key monitoring site in the Australian National Recovery Plan for Marine Turtles. Every year teams of Kakadu park staff, traditional owners and conservation volunteers camp on Field Island over a four week period to study the turtles as they come ashore to nest. Surveying began in the 1980s and has continued annually since 1994.
The study helps us to better understand the species and their movements, and to monitor the effects of threats such as climate change. Our research indicates that the population of female turtles that continuously return to Field Island remains stable. The data we collect is pivotal in monitoring flatback turtle populations at a regional and national scale.
2011
This year 71 turtles were recorded on Gardangarl in the survey period, with at least 48 successfully nesting.
2010
This year 114 turtles were recorded, a record high in the last five years! The teams had some extremely busy nights with 17 turtles coming up to lay on one particular night. A highlight for some was seeing hatchlings scramble out of the sand and making their way to the water.
