3rd Apr

Cane toads still a problem

Those of us who were around in the 1960s (and who can remember anything at all!) would recall the incredible numbers of toads in those years. You’d be kicking them off the path to get in the front door. They were thick on the roads, and the stories of dogs and other critters dropping after a poison spray from a toad were widespread.

It’s well known that cane toads were introduced to Australia from Hawaii in the 1930s in a futile attempt to control cane beetle in sugar crops. However, leading researcher Dr. David Newell of SCU says a second introduction took place at Byron Bay about 1965. None were observed in Lismore in a 1979 survey, but were found there in 1990.

Over the decades the toads in our region seemed to have fallen in number, with only the odd one seen on the road these days. However, they’re hanging in there particularly in wet years such as 2010, and are still a problem for our wildlife. Ground animals, native frogs, snakes, lizards and birds are affected.

There’s a story about a recent event at Woody Head where a stowaway toad arrived in the camping area, and was attacked by a monitor lizard. The monitor then dropped dead in front of horrified onlookers. Cane Toads have been declared a Key Threatening Process, and a Draft Toad Abatement Plan (Australian Government) is out for comment.

Wendy Gibney and Scott Hetherington of Byron Council recently undertook a Cane Toad control program funded by the NSW Environmental Trust. It was a 3-year “toad muster” project. Wendy and Scott have organized several musters, done a lot of talks, and issued 23 toad traps. The traps however are not seen as all that effective. In most cases manual collecting has far outdone traps in numbers caught.

There is a lot of variation in toad numbers in each area. For example 202 toads were collected in one night at Suffolk Park but only a few in some other areas.

Toads love mowed lawns, lagoons (including farm dams) and roads. Excluding toads from shallow-edged waterbodies is a high priority. A big question about collecting them is: “is it a waste of time?”

The consensus among the people who’ve done it in a big way is that it’s very worthwhile to collect the adults in musters and individual efforts, and the consequent reduction in toad numbers in an area is observable and pleasing. The toads have been virtually eliminated at Port Macquarie over 10 years, following 3 initial years of intensive effort.

A major anti-toad effort is underway in the Clarence valley, with a total of 6,000 caught this year already. They’ve split the valley into 8 zones, and in Yamba alone have netted 2,271 toads. Rural landowners in that area have also been enthusiastic collectors from their dams and ponds.

The main spark plug in that effort seems to be Sharon Lehmann. Sharon says an effective community-driven toad control program needs the tools (nets, information), people need to know the efforts are worthwhile, there must be coordination, regular communication and feedback, and of course a key person or two to drive it along.

David Newell says that based on his extensive research in the Border Ranges it’s likely that toads are using farm dams as a major breeding habitat, and spreading via the road network to other habitat areas, including into rainforest. They spread along the coast faster than in inland areas, and have made about 4km a year in our region. In the NT this rate of advance has ramped up to 50km a year.

Systematic capture on consecutive nights is highly effective in getting the population in any one place. You need to go back a couple times. The main predators of “metamorphs” (the tiny juveniles in their thousands) are thought to be adult cane toads. Only about 1% of juveniles survive to adult toads. Males have a more yellow colouring, and females are darker. Some evidence is merging that they are affected by parasites, and researchers are looking at possible biological controls. White-faced Egrets are thought to be preying on them, and perhaps other birds, possibly owls. Anyone out there seen birds eating toads?

Wendy Gibney has done autopsies on hundreds of toads and found the main item of diet in this area is (1) ants, (2) beetles, and (3) snails. In one big toad found near the coast seafood was the main stomach item.

With the number of watery areas around Bangalow, and the pollution control wetlands existing and planned for Bangalow, we need to be mindful of the toad menace. When wetlands are fully planted there is little risk, as the toads don’t like vegetation. Toads like farm dams with cattle access so they can hop easily across the cleared surface. Dams should have vegetation such as Juncus (tussocks) planted around the edges.

We intend to organise toad musters in Bangalow. Kids like the toad musters. They grab the collection nets, like the safety vests and love roaming around in the night with torches. We need to identify toad “hot spots” around Bangalow so encourage everyone to listen for the calls (a kind of drawn-out high-pitched “boop-boop-boop”), and take a walk around areas that hold water at night. Let us know on the website. David Pont

Dave (about the author)
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