Found all this most fascinating David .. especially after watching on the ABC
last night the show titled Cane Toad: The Conquest.
-----Original Message-----
From: David James <>
To: Del Richards <>; birding-aus
<>
Sent: Wed, Feb 1, 2012 3:08 pm
Subject: Roufous Night Heron dismembering Cane Toads.
Here is some latent information from a birder who previously conducted
cientific reasearch on Cane Toads and other frogs in North Qld. The toxic parts
f adult Cane Toads are the paratoid glands on the shoulders, the dorsal skin
nd the ovaries. Quite a number of animals have learnt to eat the non-toxic
arts by flipping the toads and chomping through the underbelly. Mostly they eat
he internal organs (except the ovaries) and the thigh muscle meat. In
ownsville in the 1990s I recorded Aust White Ibis, Black Kites, Australian
avens and Water Rats doing this regularly. None however, left a tiny hole in
he throat, they sliced the belly wide open. All searched for them
ystematically, apparently following the theory of search pattern behaviour .
t one point I had 24 open pens in a cow paddock by a dam, each with a single
dult and 10-30 tiny metamorphs (i.e. newly metamorphosed from tadpoles). The
dults started mysteriously disappearing
after a couple of days. Turned out that a flock of Ravens that had learnt to
heck the pens at dawn each day, flip and kill the toads and then cache them in
rees. The sympatric Torresian Crows showed no interest in the Toads, but the
avens would defended my pens from their rival Crows all the same.
t does not surprise me that Night Herons also eat Cane Toads, and I'm sure
any other herons do too. However, I would be surprised if Night Herons did so
y making a small incision in the throat. They might be able to get the gut that
ay, but not the heart or the thigh meat. I'm not sure what would eat them that
ay, but suspect it might be something capable of crawling inside, a centipede
erhaps? Dissecting one of these victims might help.
ew things can eat a toad whole. A lot of snakes, goannas and quolls have
pparently died trying to do so. The widespread decline of these
readators still puzzles me a little, because the Common Green Tree Frog is just
s toxic as the Cane Toad. These predators learn not to eat Green frogs, but
ften don't learn to eat toads. Many of your listeners will know that their
uppies learn not to eat toads and green frogs alike after only lick of each,
ut might be sick for a day or two afterwards (and then pretend not to notice
rogs for the rest of their lives). The Keelback, a common water snake that
pecialises in eating frogs, eats the young metamorphs whole, and even seems to
refer them to other frogs, at least sometimes. Meat Ants swarm and devour small
oads. Green Tree ants will carry flattened and dried road killed toads in one
iece up a tree to their nests in extrodrinary displays of determination. A
hoto of a Papuan Frogmouth with a frog in
its bill was published on the back cover of wingspan maybe 15 years ago, with
he suggestion it may have been a Cane Toad, but who knows. In my pens, I
bserved naive juvenile Pied Butcherbirds trying unsuccessfully to eat my
etamorph toads. They would pick them up and fiddle with them in their bills but
uickly drop them (alive and unharmed) and try another. I assume the small
arcel of edible meat wrapped in poisonous skin is too difficult to process,
nlike the adult toads.
he question is often asked by frog researchers "why are metamorph Cane
oads diurnal when most other frogs are nocturnal?". They usually offer answers
ike the night is too cold or some other reason why metamorphs are unable to be
ctive at night. I would suggest that they are able to be active by day when
ost other frogs (including adult toads) cannot be, because they have better
efence against predatory diurnal birds.
ncidently, the tadpoles are very poionous too, and few predators can handle
hem. This allows them to breed in water with fish, unlike native frogs. A
olleague was studying what did and did not eat the tadpoles, but so long ago I
an't recall much. Dragonfly larvae snip the tails off the taddies, which
eaves them to die floundering helplessly.
avid James,
n Jakarta
==============================
_______________________________
rom: Del Richards <>
o:
ent: Wednesday, 1 February 2012 11:54 AM
ubject: [Birding-Aus] Roufous Night Heron dismembering Cane Toads.
Over some years I have had a programme "Bird Talk Back" on ABC Far North in
airns. Yesterday (31/01/2012) I fielded ten calls in thirty minutes.
Early in the programme a caller from Walkamin (between Mareeba and Atherton)
ad found four dead cane toads with an small incision in their throat by her
mall backyard pond.
I told her plainly that it was a good mystery thinking that it would be
nimal attack rather than bird predation. About three calls later a gent from
ordonvale south of Cairns assured us that he had watched White-tailed Rats and
surprise, surprise!) Northern Brown Bandicoots kill and eat the non-toxic
nderside parts of cane toads.
Minutes later the mystery was solved when George who owned a piggery at
alkamin called in to tell us about Roufous Night Herons. He related that after
n early evening storm one time he checked the piggery and that a night heron
as moving through the pig pens and systematically flipping cane toads on their
ack and taking out their innards.
Given the shape and dexterity of their pointed bill the night heron would be
ell able to extract the gut through a small incision. On my next programme I
ill endeavour to follow the thread on birds and cane toads in an effort to
erive some more latent information that is held out there by everyday
on-scientific observers.
Del. Richards, Fine Feather Tours, Mossman, NQ.
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