Turtles on the comeback trail in Cape York
You can tell what animal has raided a turtle nest.
Goannas leave a small hole and suck out the egg, rich in protein; dingoes eat a few and wander off; pigs trash the nest and leave a trail of destruction along the beach.
Marine turtle nesting sites in Western Cape York in Far North Queensland are vital for three of Australia’s six marine turtle species.
Called minh miintin in local Wik-Mungkan language, they have important cultural significance for the local community.
All three turtles, the Olive Ridley, the Flatback and the Hawksbill are on the International Union for Conservation of Nature (IUCN) Red List for vulnerable species. In Australia the Olive Ridley is endangered while the Flatback and Hawksbill are considered to be vulnerable.
Cape York might be the largest nesting place in the world for the Flatback turtles, it also has the biggest concentration of minh nhinthan, or feral pigs, in Australia. Five years ago in Western Cape York, sea turtle eggs were being decimated by them.
The pigs were wreaking havoc on the colony by eating turtle eggs (minh nhepan miitin), and despite thousands of pigs being shot annually, none of the turtle eggs was surviving.
Today the survival rate has skyrocketed through an innovative collaboration between CSIRO scientists, Balkanu (Cape York Development Corporation), Traditional Owners and Indigenous Rangers.
“From a predation rate of 100 percent in 2012 we have got it down to an average of 26 percent,” says Dr Justin Perry, CSIRO ecologist.
“There was an assumption that shooting lots of pigs will save marine turtles. We found that shooting pigs on the flood plains had very little impact on the predation of marine turtle eggs.”
Turning the problem around
Desperate for a better solution, a meeting was held between CSIRO scientists, Aak Puul Ngantam (APN; a Wik Traditional Owner group), Balkanu and Indigenous Ranger groups, to decide how best to protect the marine turtles. The result was a unique partnership where the researchers supported Traditional Owners with the science they need to make decisions on how to manage their land.
“The real change came about when we started working together,” says Perry.
Rather than concentrating on shooting as many pigs as possible, the group decided to shift the focus to protecting hatchlings. They created a holistic conservation program which included monitoring turtle nests and learning more about pig behaviour in order to create targeted control and protection programs.
Balkanu is working with Indigenous Rangers from APN to monitor the turtle nests over the breeding season between February and November.
“The pigs are doing a lot of damage to our country. They dig up a lot the turtle eggs and destroy them,” says Dion Koomeeta, APN Ranger.
In the breeding season rangers use quad bikes to monitor a 47 km stretch of beach including any predation by pigs, wild dogs or goannas. Rangers are also conducting helicopter surveys on more than 100 km of prime turtle nesting beaches for three days at the start, middle and end of the turtle nesting season to identify nesting and predation hotspots that will guide their future management strategies.
“We record any new nests or tracks using an app which has been developed specifically for this project,” says Brian Ross, Balkanu Project Manager.
Fencing out the pigs
Rangers are also installing chemical fencing – lines of 1080 bait – to protect nesting areas from pigs. Before introducing the poison the rangers free feed the pigs for about a month, which ensures the baits attract as many pigs as possible. Using time-lapse cameras the rangers can tell if the pigs are coming to the feeding stations.
“Chemical fencing might only remove 100 pigs, but it’s effective because it removes the right pigs,” says Ross.
“Aerial shooting can remove 1000 pigs over three to four days. It’s still important, but it doesn’t target the right pigs.”
Using data collected over three years and local knowledge the team were able to install around two km of pig proof fencing which protects more than 19 km of beach.
“It should protect about 15,000 turtle hatchlings a year,” says Ross.
Using tech at landscape scale
The success of the pig management project has also led to discussions about how new methods could be developed to better manage pigs across the whole landscape.
“We were trying to understand where the pigs were and how they used the landscape over time. Because helicopters are very expensive and time consuming, we could only survey the pigs six days a year to get snapshots of their behavior,” says Perry.
“So we dreamed up the idea for a mass feral animal tracking program.”
Using technology similar to Fitbit trackers it is possible to monitor the pigs 365 days a year. An order of magnitude cheaper than GPS collars, which are around $4000 each, the new tracking collars will help researchers and land managers understand where and why the pigs move around the landscape.
The researchers also needed to understand what are the changes in the environment that make pigs shift: perhaps a food or water source has disappeared, or the temperature has gone up – pigs can’t sweat so they must move to cooler areas when temperatures exceed 31 degrees celsius.
CSIRO is working with ranger groups to install a network of low-cost miniature weather stations to develop an understanding of the microclimate in the area.
Once key pig food sources have been identified, strategically located pig fencing can be used to exclude feral pigs. Not only will this protect the landscape, but it should reduce pig numbers because it reduces their access to high quality food in the dry season limiting their ability to breed.
Keeping Country beautiful
Five years after the initial project started 74 per cent of the eggs are surviving.
“This project is a good example of why you need time to solve environmental problems,” says Perry.
And there are other benefits too, says Bryce Koongoteema, APN Ranger: “It’s good for keeping the land beautiful and taking care of Country.”