Come out of shell for turtles
EFFORTS to preserve Bibra Lake’s native turtle population are being ramped up on the eve of nesting season, with the City of Cockburn re-iterating the need to further reduce mortality rates.
The area’s population of threatened southwestern snake-necked turtles has showed signs of slight improvement since a horror 2018, when 13 turtles were killed on Progress Drive in a single night.
Research by Murdoch University PhD student Anthony Santoro found a drastic drop in incidents of nesting females being struck by vehicles, from 15 in 2018-19 to two in 2019-20.
His research also found the number of nesting turtles killed by predators had dropped from 25 to 17 and nests found raided by predators had reduced from 135 to 120.
But Mr Santoro said there was still much work to do and they could not afford to get complacent, especially with nesting season set to run from this month until February.
“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’ amphib
ious reptiles a priority,” he said.
“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 said due to the turtles’ long life spans, delayed sexual maturity and
low hatchling survival ( just 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. His thoughts were echoed by City of Cockburn environment manager Chris Beaton, who said these efforts needed to be repeated
if the turtle population was to survive and thrive longterm.
“Ongoing research by Mr Santoro has shown marginal improvements in the survival of nesting female turtles, their nests and hopefully their hatchlings over the past two years,” he 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.”
One of the reasons for the improvement over the past year can be put down to a dedicated group of ‘Turtle Trackers’, volunteers who helped protect nests and eggs.
Mr Santoro helped establish the citizen science program, which has about 30 volunteers and in the past year identified 25 nests around Bibra Lake.
Those nests were protected by cages installed by project partners Native ARC and The Wetlands Centre Cockburn to provide protection for nesting females and their eggs 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.”
The City of Cockburn is helping further protect nesting turtles with training for new volunteer Turtle Trackers, increased feral animal control in the area, improved fencing, ongoing traffic education along Progress Drive, wildlife cameras around Bibra Lake and GPS trackers to aid research movements.
To become a Turtle Tracker, visit the City of Cockburn website.
Vicky Hartill, Anthony Santoro and Rachel Pearsall with Tommy the turtle in Bibra Lake and inset, a juvenile southwestern snake-necked turtle, which is only the size of a 50c coin when born.