Westconnex threatens few surviving Green and Golden Bell Frogs at Arncliffe

 ( Ed: This piece is by scientist Grant Webster.  He writes that the EIS underestimates the negative biodiversity impacts of the New M5. As Grant informed the Federal Department of Environment last year, he has photographed a Green and Golden Bell Frog breeding event on the Kogarah Golf course, a large part of which will be taken over by Westconnex for a massive construction site for the New M5.  Many hoped that the Federal government would refuse consent for WestCONnex to occupy the site which is home to what is probably one of only two colonies of Green and Golden Bell frogs in Sydney but instead the Federal Minister Greg Hunt delegated the decision to the NSW Department of Planning. You would have assumed the consultants would have contacted Webster or at least read his submission. The People’s EIS finds it disturbing that the consultants who prepared the EIS seem to have ignored the photographed breeding event. You can read the Biodiversity EIS study in Vol. 2h Appendix S  

The new M5 (WestCONnex) EIS makes it clear, there will be unavoidable serious impacts to the endangered Green and Golden Bell Frog (Litoria aurea) and the critically endangered community Cooks River Castlereagh Ironbark Forest, if the road is to go ahead.

 Green and Golden Bell Frog threatened

The Green and Golden Bell Frog was once one of the most common frog species found on the east coast of New South Wales and it was once abundant in the swampy eastern suburbs of Sydney.

This all began to change in the 1970’s when the ongoing impacts of habitat loss, habitat degradation and habitat fragmentation were amplified by cumulative effects of urban consolidation and development including roads, cars, pollution, cats, dogs, the introduced plague minnow and finally with the introduction of the amphibian chytrid fungus (chytridiomycosis), this was the final straw for the bell frog which was now suffering death by multiple causes. The most common frog in eastern Sydney had become the most endangered by the 1990’s.

By this time the bell frogs were reduced to a series of small ‘key populations’ scattered along the coastal fringe of New South Wales. Four of these populations were located in Sydney – Arncliffe (Kogarah Golf Course – the population at risk from this development), Homebush Bay, Kurnell and Greenacre. It is now almost 2016 and the situation for the bell frogs of Sydney has not improved. With the exception of the Homebush Bay population which has expanded into newly constructed wetlands throughout Sydney Olympic Park, the remaining populations in Sydney have been ignored and left to dwindle with their habitats largely succumbing to weed invasion and modified water quality. The status of the Greenacre population is unknown, the Kurnell population has suffered apparent extinction and can no longer be found, and the Arncliffe population has managed to just hang on with the most recent population estimates being 30 to 50 adults.

With this being the case the small and fragile Arncliffe population, what may be the second last population of bell frogs in Sydney, is now to be at the centre of a massive four year development for westCONnex.

The Arncliffe Bell Frog population is confined to Kogarah Golf Course and the adjacent RTA ponds and occupy and area covering about 40 Ha. For the westCONnex development, 7.82 Ha of bell frog foraging, dispersal, sheltering and potentially breeding habitat is to be removed from the golf course. This is expected to have “direct impacts” on the bell frogs, including: mortality and injury of individuals during clearing of shelter habitat, decommissioning of ponds, during operation of permanent facilities and decreased habitat value of the RTA ponds (where the frogs breed). Decreased habitat value of the RTA pond includes “indirect impacts” of shading, dust, noise, vibration and lighting from the adjacent works. As part of their mitigation measures frog exclusion fencing, translocation and captive breeding have been suggested as solutions.

New M5 could kill off GGBF population on Kogarah Golf Course

So what does this mean for the Arncliffe bell frogs? It could very well mean the end for the population. Taking into consideration the population is already very small (<50 individuals over 40 Ha) and entirely restricted to Kogarah Golf Course, the destruction of 7.82 Ha of dispersal habitat, the addition frog exclusion fencing confining individuals to the area around the RTA ponds and reduced quality of the RTA ponds over four years (or four breeding seasons) can only result in detrimental impacts on the frogs. The construction on Kogarah Golf Course is occurring immediately adjacent to the RTA ponds on the area of the golf course the frogs most often use for dispersal and occasionally breeding. Given that bell frogs are a widely dispersing species that often utilise different breeding sites (depending on site suitability in different years) confining them all to the one place would likely result in a higher level of cannibalisation, especially of juveniles which need to be able to disperse away from the pond to avoid the adults.

RTA ponds now in poor condition

The suitability of the RTA ponds to see the bell frogs through this tough time must also be considered, if this is where they are expected to breed and survive. The RTA ponds are now over 15 years old, densely covered in vegetation and did not support any breeding in 2014. Bell frogs have shown preference for new ponds, ponds with open areas free of vegetation and require grassy areas adjacent to the pond for foraging. Under the new arrangement the suitability of the RTA ponds to support the bell frogs is severely reduced. Bell frogs will only breed in water if the temperature is above 22 degrees, and in a shaded pond covered in dust and vegetation reaching this critical temperature for breeding may be problematic.

Loud noise may interfere with breeding

Loud noise has been demonstrated to interfere with breeding of larger frog species, so with 24 hr construction activities producing noise and lighting at night, it is easy to see how the frogs may not feel secure enough for breeding to occur, that’s if the water even reaches 22 degrees! If the RTA ponds are unsuitable for breeding the frogs may wish to look elsewhere, this will be very difficult for them if the ponds are surrounded by frog exclusion fencing and if the additional ponds are also removed on the golf course the frogs will be left with nothing. Further, as colonising species, if any frogs happen to be on the wrong side of the frog fencing than any hole in the ground that fills up with water after rain in the construction zone may become the new favourite hangout for the local frogs which would result in a stop work procedure should they be found on site.

Translocation rarely works

As for their mitigation measures, frogs are expected to be translocated off site, however this rarely works as frogs will often return directly to the place they are taken from. This is where the frog fencing hopes to prevent frogs from being injured or killed as they disperse over the construction site, but by confining them all to the one small area; it is really a double edged sword. WestCONnex have also suggested captive breeding to maintain stock of the frogs while works continue. This may be the only chance the frogs have, and only if it is done properly. As breeding may not occur while construction is happening, if captive breeding was done carefully and with the ongoing release of tadpoles on site over the years of construction it may be sufficient to see the population through, however it may result in a bunch of very well fed adults around the RTA ponds surviving on juveniles which could not disperse beyond the frog fencing. Only a breeding program that regularly supplements tadpoles over the years of the construction would help, a bulk tadpole release at the end of construction won’t help as re-establishment of bell frogs in areas where they have been depleted in the past has not been shown to work. As bell frogs are rather easy to breed in captivity a captive stock can be and should be maintained over the course of the works.

Despite the mitigation measures proposed, this is really disaster for the Arncliffe bell frogs. If death by multiple causes is responsible for the bell frog decline across New South Wales, it is easy to see how death by multiple causes resulting from westCONnex may be the end for the bell frogs here too. The EIS also does a good job of downplaying the threat to the bell frogs, it highlights that there are several populations in Sydney without referring to the status of each one, it suggests the area of golf course to be developed is not as important to the frogs as it is, despite being the main area of dispersal and foraging habitat for the bell frogs it may also be an important additional breeding area. The EIS states that breeding has not occurred outside the RTA ponds since 2000, however this is untrue as I myself have recorded breeding in the golf course ponds as recently as 2009. Further no additional bell frog surveys, outside the scope of regular annual monitoring have been conducted to assess the population or better understand the population dynamics. In a delicate system like this, any interference could be disastrous, and the picture being painted by westCONnex for the frogs is exactly that.

Photo of Green and Golden Bell Frog mating on Kogarah Golf course - by Grant Webster
Photo of Green and Golden Bell Frog mating on Kogarah Golf course – by Grant Webster

Quote WebisterCooks River Castlereagh Ironbark Forest

Sydney’s native vegetation communities have been subjected to intense clearing in the last 200 years. Some of these unique communities include Sydney Blue Gum High Forest (>95% cleared), Cumberland Plain Woodland (94% cleared), Sydney Turpentine Ironbark Forest (95-99.5% cleared) and Shale Sandstone transition forest (>80% cleared). All of these communities are listed as endangered or critically endangered. Cooks River Castlereagh Ironbark Forest (CRCIF) is another one of these critically endangered Sydney vegetation communities, sitting on about 95% cleared. Sydney’s natural heritage is clearly very threatened by ongoing development with so much of our native forest already gone to ‘development’ and expansion.

EIS underestimated impacts on critically endangered bushland

A small patch of CRCIF occurs in the westCONnex development footprint, 1.87 Ha of intact forest known as Beverly Grove Bushland. For the construction of the road 1.4 Ha of this forest is expected to be cleared. Although they note it is only a small amount of the total area of remnant CRCIF (about 0.1%) the impacts on this community are worse than implied. What is interestingly omitted from the EIS is that fact that by reducing the size of Beverly Grove Bushland to 0.47 Ha it actually reduces the size of the patch to below 0.5 Ha, the critical size threshold for a patch of forest, meaning the remaining patch of bushland will no longer be considered CRCIF! They should state the total loss of extent of CRCIF will be 1.87 Ha. This also means the remaining bushland will not be entitled to the ‘protection’ of a critically endangered ecological community that it currently has.

Cooks River Iron Bark forest – EIS neglects to mention Westconnex will wipe out so much, the rest won’t be regarded as worth labelling critically endangered

Drawing  down of groundwater

More bad news for the local forest communities including the CRCIF is the drawdown of groundwater for the tunnelling associated with westCONnex. The EIS states that the vegetation communities may be dependent on groundwater and that with the reduction of groundwater certain plant species may be negatively affected especially in dry periods. However what the impacts of the reduction of groundwater on these communities will be is unclear.

Threatened Swamp Sclerophyll Forest also to go

In addition to the CRCIF to be cleared, a 1.82 Ha patch of threatened Swamp Sclerophyll forest (on Kogarah Golf Course) will also go, and a grand total of 10.8 Ha of vegetation (both native and exotic) is highlighted for clearing for this project. In the present context of climate change any clearing of vegetation without appropriate re-vegetation of another area is irresponsible, especially when the vegetation is being cleared for a carbon producing road!


The true biodiversity costs of this project are much greater than that presented by westCONnex, including the likely loss of the Arncliffe bell frog population and the practical loss of 100% of Beverly Grove CRCIF. In addition, the loss of Swamp Sclerophyll forest, hollow bearing trees, loss of foraging habitat for the threatened Grey-headed Flying Fox, loss of ecologically unassessed urban areas (private residences) and with the implications of climate change (both from construction and use of the road) the biodiversity costs of this project really begin to tally up. Along with the displacement of people and the expenditure of money ($16.5 billion!), the environmental costs really should have us scratching our heads and asking “is it all really worth it?”

For more on the Cooks River Iron Bark forest read

WestCONnex plans to destroy critically endangered forest 

For more on the Green and Golden Bell Frog read:

Westconnex could cause endangered frog species to croak it 



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