March 3, 2015

Soldier Crabs And Natural Toad Busters: We’re Shaping Up For An Action-Packed Autumn

Today (March 3) is World Wildlife Day, so we're publishing this blog a little earlier that usual to honour all our weird and wonderful wildlife in our backyard...

Lake McKenzie one day after TC Marcia crossed the Queensland coast at Yeppoon  Pic: Ranger Gaz
Autumn has arrived Tree huggers and Fraser Island has come alive as the southerly breezes roll in and the wet season departs.  We’re pleased to report that last month’s Tropical Cyclone Marcia – which hit the headlines worldwide and crossed the Queensland coast at Yeppoon, some 435 kilometres (or a 5 hour drive) to the north of Hervey Bay - scooted around us and did not leave a noticeable footprint on our shores.

In and around the resort this month, our staff and guests continue to be inspired by some of our smallest critters which we have discovered on our daily walks/talks out and about on the island – so we hope you enjoy the read.

Guests on our guided walks are always blown away by the sheer quantity of blue-tinged Soldier Crabs (Mictyris longicarpus) that habitually appear in immense numbers in the inter-tidal zone along the foreshore of the western beach.  These crabs are so named because the males patrol the beach at low tide in large armies walking forwards - not sideways like other species of crabs including the Ghost Crabs (Ocypode cordimana), Sand Bubbler Crabs (Scopimera inflata) and Orange-clawed Fiddler Crabs (Uca vomeris), which are also found right here on Fraser Island.

A lone Solider Crab on the western beach of Fraser
DID YOU KNOW Soldier Crabs feed on detritus (organic matter produced by the decomposition of organisms) and microorganisms in the sand? They do this by travelling across the beach at low tide and by using their claws bring sand up to their mouth – a process which leaves round pellets on the beach behind them.

When the feeding’s done; the tide rises; or if spooked, the crabs bury themselves in a corkscrew fashion under the sand in essentially a sand cocoon with enough room for air and a sand cap on top for added protection against predators such as migratory wader birds and rays.

A stone’s throw from the beach, and we have been under attack in our Wallum heath by the villainous feral Cane Toad (Rhinella marina) – a species that is native to Central and South America and was introduced into Australia to control the native grey-backed cane beetle which were destroying sugar crops.  Since their release, feral toads have bred rapidly and have fast become pests in their own right.
Cane Toad  Pic: camilletravels.wordpress.com

FERAL FACT: According to Wikipedia, the long-term effects of toads on the Australian environment are difficult to determine, however effects include the depletion of native species that die eating cane toads; the poisoning of pets and humans; depletion of native fauna preyed on by cane toads; and reduced prey populations for native insectivores, such as skinks.

In news that has the scientific community on their toady toes, a group of scientists from the University of Sydney have been trialling a new eradication program at Waddy Point on Fraser Island - using the cane toads’ venom against their spawn aims to stop the breeding cycle. Cane Toad tadpoles are attracted by the venom and are caught in traps – researchers caught up to 10,000 a day - whilst native tadpoles are repelled by the venom and hop the other way.

The scientists say results have been excellent and that this novel approach could hold the key to completely eradicating this pest in our island backyard.  Until this happens, we have our very own superhero to help thwart this dastardly foe - the one and only Keelback or Freshwater Snake (Tropidonophis mairii).  This very mild-mannered, non-venomous snake is a part of the Colubridae family of ‘rear fanged’ snakes which includes a couple of other island residents - the Brown Tree Snake or ‘Night Tiger’ (Boiga irregularis), and the Common or Green Tree Snake (Dendrelaphis punctulata).
Keelbacks eat toads and frogs. Pic: canetoadsinoz.com

Rarely seen around the resort, you’ll find Keelbacks in well-watered habitats near creeks or in low lying areas on Fraser Island as well as along the eastern and northern coasts of Queensland.

What we love is that this species has become a true unsung hero of Fraser Island - and Queensland for that matter - as they are one of the only native snake species to have a tolerance to the bufotoxin, which Cane Toads produce from glands along their backs and behind their eyes.  This, of course, has allowed them to successfully prey upon our island feral Cane Toads and help control population numbers.

As you can see, it’s been an action-packed last month and, if you’re an environmental nerd like us, or just have a natural curiosity for nature – then we definitely have something here on Fraser Island to pique your interest.  Until next time fellow eco-enthusiasts, this is Ranger Aaron signing off from Kingfisher Bay Resort.

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