The distribution of the green python (Morelia viridis) in Australia

Abstract

The green python (Morelia viridis) is an iconic snake species that is highly sought after in the captive pet trade and therefore the target of illegal collection. Despite their popularity and an increase in wildlife conservation in recent years, some important ecological attributes of green pythons remain unknown. This makes their effective conservation management difficult. The aim of this research was to determine the detailed distribution, relative abundance and demographic status of the green python in Cape York Peninsula, Australia. Presence/absence surveys were conducted throughout the potential range of the green python and intensive mark-recapture surveys in the areas where there have been previous records. Green pythons were located in the Iron, McIlwraith and Kawadji-Ngaachi ranges of Cape York, distributed over an estimated area of 2289 km2 where they frequented rainforest habitats and adjacent vine thickets. However, despite anecdotal records, they were not found in the Lockerbie Scrub or Jardine River Catchment. Green pythons were encountered most frequently in the Iron Range area where their density was estimated to be 540 km-2 compared with an estimated density of 200 km-2 in the McIlwraith Range. Mature individuals comprised 83% of snakes caught in the McIlwraith Range, whereas only 56% of those captured in the Iron Range were mature. This study has shown that green pythons are common in suitable local habitat. The differences between their abundance and population structures in the Iron and McIlwraith ranges may be due to differences in prey abundance and the possible impact of poaching. The current distribution of green pythons in Australia is consistent with a rainforest connection with New Guinea during the Pleistocene and it is postulated that the two populations have been separated for at least the last 250000 years. The detailed distribution of green python populations in Cape York, combined with baseline data on their demographic variability, now provides a foundation for the informed conservation management of this species.