The cane toad (Bufo marinus) is native to northern South America, parts of Central America and Southern Texas. It was deliberately imported from Hawaii in 1935 and introduced into Australia’s tropical north-east in an unsuccessful attempt to control the cane beetle, a damaging insect pest of sugarcane crops. The toads quickly established in the new environment and began to spread. Today, they inhabit most of the Australian tropics and sub-tropics and have reached Western Australia. Their great expansion can be attributed to the combination of being highly adaptable to a range of environmental and climatic conditions, high fecundity and also being highly unpalatable.
Cane toads release potent toxins from their parotid glands as a defence strategy and predators who attempt to consume toads can be killed by ingestion of these toxins. Cane toad eggs also contain high levels of toxins and are also a danger to vertebrate predators. The direct impact of cane toads in Australia has been extensively studied and a review of this research has revealed that it is the lethal toxic ingestion of toads by frog-eating predators that is the major single mechanism of impact (Shine 2010). Although the cane toad has not been responsible for the extinction of any native species, some populations of predator species (varanid and scincid lizards, elapid snakes, freshwater crocodiles, and dasyurid marsupials) may be vulnerable, especially when toads first appear in a new area. However this negative impact can be variable and some of the taxa severely impacted by toad invasion recover within a few decades, via aversion learning and longer-term adaptive changes. The indirect impacts of toads such as food-web mediated effects are less understood and research is continuing in this area.
The control of cane toads is challenging because of their wide-spread distribution, large population numbers, high breeding capacity, small size and burrowing behaviour. Years of investigation into potential biocontrol agents have not yet been successful and currently there is no effective tool for broad-scale reduction of toad populations. Therefore, in the short term, management focuses on frontline surveys and removal of toads. Removal involves the intensive collection of toads by hand, sometimes aided by traps and/or barrier/deflection fencing.
This Standard Operating Procedure (SOP) contains current best practice for the euthanasia (or humane killing) of cane toads. The recommendations are based on information in the literature as well as behavioural observations and time to death recorded in a project to examine the welfare impact on cane toads of a range of euthanasia techniques. The research was conducted at the School of Biological Sciences, University of Wollongong (UOW): ‘Evaluating the humaneness of known-to-be-lethal euthanasia techniques for cane toads that are used by community groups’ (Munn and Lothian, 2010, unpublished). As new information becomes available the appropriateness of euthanasia methods for cane toads will be reviewed.
This SOP is a guide only; it does not replace or override the legislation that applies in the relevant State or Territory jurisdiction. The guidelines should only be used subject to the applicable legal requirements (including OH&S) operating in the relevant jurisdiction.