Snake population near death as floods drown rats

Conor Byrne and Annie Brown, Friday November 1, 2019 - 17:04 EDT



Snakes on a plain: Deakin University Professor Tom Madsen in happier times in 2009 when water pythons were plentiful on the Adelaide River floodplain in the Northern Territory - ABC licensed



The world's 'most productive ecosystem' is about to collapse because extreme rainfall has caused a famine, a Darwin wetlands researcher of 30 years has said.



Dusky rat populations on the Adelaide River Floodplain at Fogg Dam have bottomed out, and predator populations of pythons are almost non-existent as a result, Deakin University professor Tom Madson told ABC Radio Darwin's Adam Steer.



'The rats can rebound really well but if you wipe them out so there's hardly any left, then it will take some time to come back,' he said.





'The rats are the hamburgers for the birds of prey and the pythons'.







The snakes no longer give a rat's...



Professor Madsen has counted nearly 9000 snakes on the Adelaide River floodplain over thirty years - but only found 34 water pythons in his most recent research trip.

'Thirty of those will be dead in a month because they were so emaciated. They could hardly move,' he said.

'In the same period in 2007, I'd have caught 500 snakes.'

The rats are aquatic but unable to handle large extended floods where there may be no land above water for kilometres.



Drowned rats



He blames local floods in 2007, 2011 and 2018 and points a finger squarely at climate change.

'All the predators need the rats. There's nothing else else for the predators to feed on,' he said.

'The Adelaide river ecosystem is the most productive ecosystem in the world. There's nothing close to it.

'The dusky rat has the highest biomass of any mammal in the world - that's the number of kilos per square kilometre.

'In normal years (the biomass) is three to six tonnes. No mammal has that density.

'I think they'll come back. But God knows when.



'If they don't come back this year, then there's no chance for the pythons'.







What happens if they don't come back?



'The whole ecosystem crashes,' Professor Madsen said.

He co-authored a paper in 2016 on the subject, published in Functional Ecology, which concluded: 'Unfortunately, our long-term data on this tropical ecosystem show that wildlife populations may be more sensitive to increased frequency of extreme climatic events than to changes in annual average conditions'.





- ABC



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