There are hypotheses that Cape York Peninsula mainland coasts once were highly important marine turtle rookeries, but due to the pre-existing constant pressure of native predators (dingoes and goannas) and now compounded greatly by invasive (feral pigs) nest predators, turtle nesting densities on the mainland have decreased. It is also questionable whether these nesting populations were historically low on the mainland, or whether they were once high but nesting stock have been depleted due to nest depredation and exacerbated by natal homing. Now with the threat of global warming and sea level rise affecting island rookeries, the significance ofthese long coastline rookeries is ever more important. However, because of remoteness, many of these beaches are not documented, except for anecdotal evidence and Traditional Owner (TO) knowledge.
Since 2012, Balkanu has been partnering with APN Cape York, Cape York Weeds and Feral Animals Program (CYWAFAP), Cape York Sustainable Futures (CYSF) and Commonwealth Scientific and Industrial Research Organisation (CSIRO) to conduct beach surveys for nesting sea turtles south of Aurukun, between the Love and Kirke Rivers. Two species are primarily found on this beach; the flatback turtle (Natator depressus) and olive ridley turtle (Lepidochelys olivacea). Flatback turtles are currently listed as vulnerable and Olive Ridley turtles as endangered by the Recovery Plan for Marine Turtles in Australia. The presence of Olive Ridley turtles (with different genetic stock to other Australia and international populations) nesting on this beach make it a unique and globally important turtle rookery. Data from 2012/2013 suggests that the beaches at South Wik are potentially some of the most important rookeries in Australia for the Olive Ridley turtle. Both species of turtle have been found to nest here between June and November, a time at which the landscape dries up, food resources dwindle, and predators start scouring for alternate food options. Feral pigs, wild dogs and goannas have been observed depredating turtle nests on this beach. The timing of the nesting season with the dry season also allows staff overland access to country. Rangers survey these beaches from June when nesting begins, until the end of November when hatching finishes.
In 2012, 10km of beach was surveyed by quad bike and footover a few months by Indigenous rangers, traditional owners and research staff, resulting in 105 nests. By the end of the nesting season 97% of these were depredated by feral pigs, 2% by wild dogs and 1% by humans. None of the recorded nests made it to the ocean in 2012 (100% depredation). This equates to 10,000 or more, dead turtle hatchlings. In 2013 an innovative control method using 1080 was trialled. On the same 10km of beach over a few months of opportunistic data taking (over 35 survey days), 103 nests were found. By the end of the 2013 nesting season, feral pig depredation had dropped from 97% to 12%, although dogs slightly increased to 12%. Overall depredation however dropped from 100% in 2012, to 24% in 2013 (0% nest survival to 76% nest survival). This is equivalent to saving 8000-10000 turtle hatchlings in one year over a 10 km stretch of beach. When this data is extrapolated to the full length (48 km) of beach, a potential of 375 nests (40,000 turtle hatchlings) could have been saved.
In 2014 surveys have been conducted again, but the program has been expanded to cover the entire beach between the Love and Kirke Rivers, spanning a total of 48km (and incorporating the original 10km). In August 2014, there was 0% pig depredation, however wild dog depredation had increased to 59%. While this may be classed as ‘natural depredation’, the impact it has on an already plundered nesting beach by feral pigs and wild dogs over the past 100 years is devastating. Placing garden mesh on nests is currently being trialled to deter depredation by wild dogs. However, the feral pig project’s funding wasn’t enough to support the continuous control and monitoring of the 48 km of nesting beach.
New funding: Nest to Ocean 2015
In 2015, Balkanu was able to secure new funding to coordinate a two-year “Nest to Ocean” program (nick named the ‘bacon and egg’ project by Cape Yorkers) under a federal and state Department of National Parks program. This project is proposed to contribute to the lack of resources on the 48 km long ‘main beach’ and as capacity allows, expand turtle nest monitoring, predator control and nest protection to a 26 km stretch of beach further to the south between the Kirke River and Knox Creek. Activities undertaken include using quads to record new nests (status, species etc.), setup pig feeding/bait stations and implement nest protection techniques (nest mesh). Aerial shoots (ideally 3 days of shooting, 3 times a year) will be conducted (mostly as part of the pig project) along the coast. The feeders are setup to form a ‘chemical fence’ along the coastal dune scrub to attract pigs that the aerial shoot misses. These feeders are then baited with 1080 to remove pigs that are potentially causing issues on the beach. With this integrated pest control method the impacts of feral animals on turtle nests can be successfully abated, and with the knowledge from previous years, we aim to achieve nest survival rates well above 70%. This could mean 100,000 more hatchlings make it to the ocean than normal.
The project has tailored its objectives to achieve the best outcomes for the environment and community whilst adhering to the Recovery Plan for Marine Turtles in Australia and the Feral Pig Threat Abatement Plan (Links on ARBSHeD page, but activate links here also). Currently the flatback turtle is listed in the recovery plan as ‘data deficient’. Over the past two years over 100 flatback nests have been recorded, logged and monitored, and the continuation of these projects will contribute to have a sufficient database of flatback records. The existing project is also in the process of producing a Feral Pig Threat Abatement Plan for Central Cape York.
Open community sessions were held in order to obtain permission from Traditional Owners to conduct these activities on country. This involved many hours of phone calls and board meetings and several APN staff and project managers visiting Aurukun to engage with TOs. This culminated in several operational briefs which document the work to be done and the TOs relevant to each section of country and what is permissible.
Visitor management has been an enormous issue in previous years. Constant illegal visitors to country saw wildfires lit, turtle nests destroyed, nest markers removed and hunting that likely affected the success of the feeders. Visitor management is currently being addressed and it is proposed that a visitor management system is setup and enforced, gates are setup at beach access sites, and signage at the entrance to country and entrance to the beaches are available. (Click here return to Feral Pigs Abatement)