Ecological notes on Crowned Snakes Elapognathus coronatus from the Archipelago of the Recherche in southwestern Australia

We collected 48 Crowned Snakes Elapognathus coronatus on Mondrain Island, in the Archipelago of the Recherche, in November 1999. Published data on the ecology of E. coronatus are based almost entirely on examination of museum specimens from mainland localities, and differ in several respects from our findings. Mondrain snakes are larger than their mainland conspecifics, and males grow much larger than females on Mondrain (mean adult snout-vent lengths of 456 vs 403 mm). In strong contrast, mainland snakes display little sexual size dimorphism (318 vs 321 mm SVL). Male crowned snakes on Mondrain differed from females in body shape as well as overall size, with males having relatively larger heads. The only prey items recorded on Mondrain were scincid lizards, whereas mainland conspecifics also feed frequently on frogs. Similar divergences between mainland and island populations have been reported in other snake species, suggesting that these peripheral populations represent a significant component of the overall ecological and morphological variation within each taxon.