Wednesday, 11 January 2017

The Rakali, Australia's answer to an Otter

A Rakali is a large semi-aquatic rodent that is Australia’s closest equivalent to an otter.  They are also commonly known as water rats, however this name bothers me as the animal is clearly different from a rat.  Recently the Australian government decided that it was time to refer to native Australian animals using aboriginal names and Rakali is the name used for this animal by the people of the Murray-Darling river system.  Rakali are present across most of Australia, along both rivers and near the sea.
A Rakali (Photo: Mike Trennery,
The Rakali is a major predator of crabs, particularly the larger semi-terrestrial crabs such as the crabs that live in mangroves and ghost crabs from sandy beaches.   Seeing a Rakali is very difficult as they are nocturnal and usually, they are detected by footprints.  In mangrove swamps near Cairns, it is common for the mangrove forest floor to be almost covered with foot prints, such is the scale of their activity.  I suspect that their presence is one of the reasons why mangrove crabs are mainly diurnal.  In turn Rakali might fall prey to large owls and pythons which also visit mangrove swamps.

Front feet leave star-shaped prints and back feet, long prints with webbed toes
Rakali also forage along beaches and I often see their footprints in freshly reworked sand of creek mouths.  Recently I found Rakali track on the beach at Slade Point near Mackay and decided to follow them.  The beach is almost a surf beach and is exposed to strong winds and high wind waves.  At both ends of the beach there is a rocky headland and the Rakali tracks ran along the high tide line from one headland to the other.  As the tide peaked just after dark, the Rakali must have traversed the beach whilst there were still traces of sunlight in the sky.  It is an audacious move for such a small animal to travel a 850 m distance completely exposed.  On the way across the beach, the Rakali caught and ate a ghost crab.

Remains of the ghost crab
Rakali reach approximately 1.3 kg in weight with a body length of nearly 40 cm so they are much larger than rats.   They are known to forage almost 3 km a night, however I don’t know if anyone has previously recorded them crossing of 850 m km of exposed beach in a few minutes. 

Dangerous, rogue waves often wash 10 m higher up than normal waves
Photo of Lamberts Lookout in moonlight at 8:30 pm
Lamberts Beach, which the Rakali crossed
Rakali often drown in crab and yabbi pots, particularly in freshwater.  In South Australia, net crayfish pots have been banned due to the toll they take on turtles, Rakali and Platypus.  If you want to use yabbi traps, please check on the internet how to avoid wildlife kills. Rakali may not swim as often in estuarine systems as they would be prone to attack by large fish and crocodiles.  Tides also expose their prey, so they may not have need to dive.