The seaward side of the bund that runs along the western fringe of Semakau Landfill is a slope of rocks gentle enough to permit a cautious stride down to a level base. Serving as a buffer between the wall proper and the mangroves of an older isle, this long stretch of uneven ground receives periodic flushings that leave behind a plain of pools and mats of slippery filaments. Hardy snails – nerites, creepers and turban shells – mow these dank meadows by day, while isolated propagules and succulent herbs launch a slower assault on cracks between the boulders and miniature terraces where soil and silt have accumulated.
Very different beasts emerge from the crevices and creeks that surround this otherwise barren land when the sun sets. The boxy little crabs that browse on the rhizophores retreat to the safety of low canopies, while mullets, silversides, perchlets and other estuarine schools exhibit a higher scale of nervousness. Archerfish and halfbeaks continue to patrol the surface, skirting clear of roots that offer an ounce of security to crescent perches, serpetine gudgeons and benighted gobies. In the shadows, too, are mud crabs with the claws to snag and teeth to crush the shells of clams and other shellfish, leaving in their wake a tell-tale midden of molluscan fragments.
What the darkening unleashes upon the inhabitants of a coastal swamp is a scattered knot of dog-faced water snakes, which emerge in discomfiting numbers to sit in puddles and probe the water margin for bodies within striking distance. Dark bars and blotches cover a grey tube of keeled scales ending in a faintly canine head with eyes set close to the snout. Many are still fingerlings little more than a foot in length, with much to go before they attain the full metre span of their parents. The smallest individuals readily beat a retreat into deeper nooks, but half-grown specimens can be surprisingly docile, delivering sluggish strikes or struggling weakly when moved to clearer pools. There, the snakes poke around for handy cavities before futility compels them to recover their composure, raise their heads and eyeball the source of their dislocation.
For all its apparent stupor, Cerberus rynchops is an able hunter. A flash of distraction, which sparked a stampede of mudskippers along the water's edge, was all it took for a two-and-a-half footer to snare a passing fish. Mild venom probably ensured that the victim put up no fight against the snake's efforts to manœuvre the mudskipper down its gullet. Such episodes probably repeat themselves every hour or so as the gobies brave a nocturnal minefield of jaws that pepper this artificial shoreline and lurk, too, in the tidal flats beyond the trees. With such stealth and a slow wave of continental strokes, the bockadam have colonised local canals and urban wetlands as well as other coastal habitats across the Indo-west Pacific, including a land that shuns the straightlaced and whose first nations gave their countrymen names rooted in a gentle dreamtime of rocks, rain and the remains of a world that has left few records of its reign and rhythms.