A concerted effort to reduce mortality rates in Bibra Lake’s native turtle population has shown some positive signs, but there’s still a long road ahead as the City prepares for the 2020/21 nesting season.
The lake’s iconic population of ‘near threatened’ Southwestern snake-necked turtles (Chelodina colliei) rallied slightly following a series of actions taken by the City of Cockburn and the local community in preparation for last year’s nesting season.
This included the heroic efforts of a dedicated band of Turtle Trackers, with the City launching a fresh callout for more volunteer citizen scientists to help protect nesting females, their nests and eggs this season (September-March).
But City of Cockburn Environment Manager Chris Beaton has reiterated the need for concerted efforts over many years if the lake’s much-loved turtle population is to survive and thrive in the long term.
“Ongoing research by City-backed Murdoch University PhD student Anthony Santoro has shown marginal improvements in the survival of nesting female turtles, their nests, and hopefully their hatchlings, over the past two years,” Mr Beaton said.
“But to see lasting results, we need to stay on the ball for the foreseeable future and bring the community with us in these efforts.”
The annual nesting season runs September to February and hatchlings generally start breaking out of their shells for their migration to the lake anywhere between March and August depending on weather conditions.
Mr Santoro said due to the turtles’ long life spans, delayed sexual maturity and low hatchling survival (about 15 per cent make it back to their home wetland), it would take at least a decade to see an upward shift in Bibra Lake population numbers.
He said vehicle strike of mature nesting females on roads around the lake had reduced markedly from 15 in 2018/19 to two in 2019/20, and nesting turtles killed by predators had reduced from 25 to 17. Nests found raided by predators had also reduced from 135 to 120.
“These are small but important gains and illustrate how much work we need to do as a community to keep the protection of these ‘near threatened’ amphibious reptiles a priority.
“It’s also worth noting the level of mortality at Bibra Lake is likely to be happening at other Perth wetlands, which makes local survival more vital than ever.”
Mr Santoro also helped the City establish the Turtle Trackers citizen science program and this small but very dedicated band of volunteers played a pivotal role in helping the turtles’ survival in the 2019/20 nesting season.
A team of about 30 volunteers successfully identified 25 nests enabling these to be protected by cages installed by project partners Native ARC and The Wetlands Centre Cockburn, giving the nesting females and their eggs further protection from predators.
Mr Santoro estimated about 50 per cent of these protected eggs hatched, with about 25 hatchlings successfully making their way to the lake.
“Once the hatchlings make it to the water, I think they have a decent shot at making it to reproductive age,” he said.
“This is why it’s very important the community join us in protecting as many of the nesting females and their nests as possible.”
What is the City doing to help protect nesting females during the 2020/21 season:
- Increased feral animal control in and around turtle nesting areas in conjunction with the Department of Biodiversity, Conservation and Attractions
- Improvements to protective fencing around 12 lakeside nesting refuges
- Improvements to directional fencing to guide turtles into the nesting refuges
- Ongoing traffic education using temporary signs including variable messaging boards and speed check signage on Progress Drive
- Training for new volunteer Turtle Trackers
- Wildlife cameras installed around Bibra Lake to track turtle predators
- 30 GPS trackers installed on nesting females to help research movements
To find out more about the Turtle Tracker program or to volunteer for the 2020/21 season, visit the City’s
website or send an
email.