Since identifying these snakes at my place as keelbacks (Tropidonopgis mairii), I have been interested to learn that this Australian, native snake species is in fact capable of eating cane toads, despite the toad's known toxicity to many Australian species. I believe this species' capacity to ingest cane toads is probably the reason they are calling my garden home! I certainly have a prevalence of cane toads.
According to a paper published by researchers from James Cook University, the keelbacks ability to tolerate moderate levels of the cane toad's toxin is a result of genetic history rather than a behavioural or physiological adaptation to cane toads since their arrival in Australia (Source). And it is likely still that keelbacks can be affected or overcome (die) as a result of ingesting too much toxin, potentially as a result of a particularly large, tasty cane toad. A case of eyes too big for their stomach, but with more fatal consequences.
If you're interested to know more about the keelback, DERM's website, as well as the Queensland Musuem's, provide some more overview information and interesting facts about this northern Australian snake species.