Dad talking to Molly trying to keep her settled
(Click photos to enlarge)
During the early 1970s, Dad (Bob Irwin) was very concerned about the 'shoot-on-sight' attitude towards crocodiles and decided that he needed to commit time and money to conserving Australia's number one predator.
The mid 1970s was a monumental period for Australia's crocodiles as legislation was established to fully protect both species, and Dad and myself (barely a teenager) spent many moons catching and translocating crocodiles caught up in the rapid human encroachment on the east coast of Queensland. Throughout our early croc-catching endeavours we utilized every known capture technique.
During the 1970s we used our knowledge and good old Aussie outback innovation and developed the soft mesh trapping technique which to this day is not only 100% effective, but also grants the trapper a wealth of knowledge about the crocodiles habits, sizes and demeanours within the territory being trapped.
Surveying the banks of the waterways for slides, claw marks, and imprints will determine the whereabouts and habits of large crocodiles. Once the crocodile's territory is determined, a suitable trap site should be located, preferably within 50m (164ft) of the crocodile's preferred haunt.
Crikey, we’ve come a long way in our croc trapping technology since 1980. Australia Zoo’s International Crocodile Rescue allows me the freedom and engineering expertise to design, build, trial and utilize the most advanced trapping techniques in the world.
To date, my most successful crocodile trapping mission was in Weipa during August 2004, when we caught 33 adult Saltwater Crocodiles in 14 days. These were all documented in our current crocodile research project titled ‘Crocs in Space’. Australia Zoo is working with the Environmental Protection Agency and the University of Queensland in carrying out the most cutting-edge croc research in the world.
Another recent testimony to the highly efficient capture of designated problem crocodiles, was the capture of 'Digger' in the Gulf of Carpentaria in one hour in total daylight. The croc was trying to get in the trap whilst Stuey was still setting it.
I use three distinct trapping methods:
All three methods require highly trained and skilled people to set them up, place them in the croc's territory and extract and restrain the captured crocodiles.
1. Soft mesh traps
Up until the 1990s this is the only trapping method I used. The most important thing with soft mesh traps is the amount of knowledge you need to set the trap and the amount of knowledge you learn about the crocs in the area you're trapping, whilst your trap is set. Soft mesh trapping provides the trapper with an intimate understanding and awareness of the entire ecosystem.
A good location for a soft mesh trap is a gently sloping to flat graded bank. It needs a solid tree with a branch height of 6m (20ft) that's capable of easily handling 400kgs (881lb) of force, within 10m (33ft) of the trap site.
The trap can be set on land within 5m (16ft) of the water; in shallow water up to 1m (3ft) in depth; or below the high tide mark so that as the tide comes in and the trap is semi submerged, water level should not exceed 1m (3ft) in height, otherwise there is a risk the trapped crocodile could drown.
The mesh used for the trap is a cod end off a scallop trawl net with a 16 tonne rating. The mesh dimensions are 50mm x 50mm (2in x 2in) in nylon cord no less than 5mm thick.
Wes and Ranger Barry Lyons admire
The trap dimensions are determined by the size of the crocodile to be captured. In the set position, a crocodile must be able to enter the trap without touching the side or roof. Dimensions for a trap designed to capture any sized crocodile in excess of 12ft (3.6m) would be 4.8m long x 1.5m wide x 0.9m high (16ft x 5ft x 3ft).
Mesh sitting well, but still needs barricades around it to stop the croc from attacking the bait from the sides.
'Wombat' at the rear of the trap
To set the trap, a trap site is cleared, the trap unrolled, short sticks are cut and driven through the mesh along the bottom on each side (this anchors the trap to the ground, ensuring an entering crocodile won't get caught up in any loose mesh on the floor of the trap). Mud and leaf mould can be scattered on the floor to help create a more natural substrate and assist in holding down the trap's shape.
It's all about sticks and strings
Sticks are then cut at approximately 1.5m (5ft) in length and driven down each side of the trap, approximately 500mm (1ft 6in) apart. The top/roof and sides are then tied to these sticks with a single hemp string. The string must be of a light breaking strain, such that a thrashing crocodile would easily break them, but also strong enough to support the trap.
Light hemp strings support the trap
Once all the stick and string supports are in place, the trap should sit in an even, rectangular shape.
A 12mm (1/2in) silver rope is woven through the mesh at the entrance/mouth of the trap, then threaded through a spliced loop on the end of the rope, to create a lasso/drawstring effect.
Stuey shows how a drawstring should pull up
The end of the trap is secured by weaving 12mm (1/2in) silver rope through the end meshes, pulled constricting style until all the mesh pulls together, then tied off securely to a large tree or object which a large crocodile could not dislodge. This is the anchor for the entire trap and must be secured, with no chance of fraying or breaking of the rope or dislodgement.
One or two (depending on crocodile size) bags filled with 50-100kg (110-220lb) of dirt, sand or mud, are hauled up at least 6m (20ft). This is achieved by attaching a 20mm (3/4in) steel ring, 200mm (8in) in diameter to a tree or branch above 6m (20ft) in height. A rope, long enough to reach from the suspended bags to a trigger mechanism, is attached to the weight bag leaving a 2m (6ft) tail on the attaching knot.
Damo climbing the tree to attach a trap ring
Once the weight bag is handed up to the trap ring, the tail is tied off to the ring, tree or branch. This holds the suspended bag whilst a suitable trigger mechanism is constructed.
The boys hauling up the weight bags
To trigger the trap, a 6mm (1/4in) silver rope (bait rope) is attached to a bait then passed directly and tautly through the back of the trap to the trigger mechanism. A spliced loop on the end of this rope slides over the trigger rod. Any jerking or pulling of the bait will now dislodge the trigger rod, setting off the trap.
A trap should never be baited unless the trapper is totally prepared for a capture.
At the trap mouth, barricades of logs, sticks and branches should be placed so the crocodile cannot get down the side of the trap. This eliminates the common problem of a crocodile setting off the trap from the outside.
Sketch of the trap
Always trigger the trap and re-set. This is critical to ensure the trap works effectively. If a crocodile escapes from an ineffective trap or triggers it from the outside, the crocodile may become TRAP WISE from a negative experience and NEVER be caught.
A lead-in bait should be placed approximately 1m (3ft) in front of the trap entrance/mouth. This is constructed of a strong nylon cord (2mm) attached to a stick or branch. A fist-sized morsel of food is secured to the cord so that the crocodile gets a taste for the bait and perhaps leaves a set of tracks at the trap site so the crocodile's size can be determined.
During the night the crocodile enters the trap, grabs the bait which dislodges the trigger, the bag is released pulling the trap mouth closed.
Once it realises it is trapped the crocodile tries to get out. The hemp strings break and the trap is loose around the croc. The sticks, which supported the trap, will be broken and knocked around without causing damage to the crocodile. No steel or damaging materials are used anywhere around the trap, sticks only.
The trap should be checked at first light. If a crocodile has been caught, a top jaw rope is secured and a blindfold is slid over the crocodile and trap. The head is then secured by tying ropes around the blindfold; this in turn secures the jaws together. Move the crocodile to an area where it is safe for it to be removed from the trap. Remove the crocodile from the trap and place it snugly into a crate ready for transport.
Here's a classic example of a trap set in shallow
water. This croc is 14 foot and well secured.
2. Gate traps
The gate trap is simply a modified version of the soft mesh trap. Instead of a weight bag and drawstring the trap utilizes a metal gate. The gate slides shut as soon as the croc attacks the bait at the back of the trap. It’s a soft mesh trap with a gate on it. The simplicity of the gate system means this trap is set up in half the time of setting up a traditional soft mesh trap. The downside is the clumsiness and bulkiness of the gate in the boat and through the mangrove mud. They work brilliantly on harder riverbanks and sandbars where there is no chance of the gate sinking into the grease-like mud.
I designed and engineered my first floating trap back in the year 2000. Over the years we continue to tweak and modify my design to ensure we’re constantly evolving with our increasing trap knowledge.
My current floating traps have been nicknamed ‘Floaters’ and they are unbelievably successful. They’ve never missed, never failed and constantly floor us with their record-breaking success.
They're constructed of aluminium for light weight and salt resistance, and stainless steel for durability. A sliding gate is propped up via a pin at the front of the trap. The crocodiles virtually swim straight to the bait at the back of the trap. As they strike the bait the gate slides shut.
Floaters have several benefits:
The top jaw roping and restraint of crocodiles from floaters is extremely dangerous work, and only highly trained, certified personnel should participate. Unfortunately, we don’t always catch our target crocodile first; we’ll often capture the shy, smaller females and this trap design makes for very easy releases.
The simplest and quickest way to restrain a croc is to jump on it and hold it down. The amount of people power required is directly proportioned to the size, aggressiveness, fitness and stamina of the each croc. If you don’t, or can’t, control the head you will be maimed or killed. Once the croc has been jumped and successfully pinned down, no one gets off, or backs off. If a croc thrashes and someone backs off, a gap will turn into a weakness, and then the hold-down team could be in danger. If you give a croc an inch it will rapidly turn it into a mile.
In wet, greasy, muddy situations, all the people that can fit on the croc won’t hold it. Greasy crocs are unrestrainable with people power; these crocs I take on my own.
The easiest place to restrain crocodiles is on nice dry sandy banks. When I’m trapping crocodiles I’m always on the lookout for dry, sandy, open areas close to the water. There’s little or no risk of a crocodile breaking free which makes it very safe for the hold-down team.
Tackling a crocodile in the water is easily the most dangerous of all. Crocodiles can develop twice the power by utilizing leverage from the water; they also have twice the speed and are mostly invisible. Without a top jaw rope even a smallish crocodile would kill me easily. It’s virtually impossible to get away from a croc in the water – you’re in their territory, and they’re the masters. Once that huge, powerful, rudder-like tail hits the water the crocodile has doubled his strength and doubled the danger element. I only ever tackle crocs in the water if there is absolutely no alternative.