Dear Birdingaussers,
I come on this server to avoid toad inquiries! But, honest, I wouldn't
resist anyway.
Yes it is true: a lot of things are claimed about toads that aren't
true. We need a good study on them.
Alas, put a student or a scientist on to research an introduced
animal and they fall in love with it. Next, the researcher is the
biggest advocate of the rights of the animal! Someone once said that
this phenomenon was like the Stockholm Syndrome: hostages, after
release, often admire and praise their captors despite the deaths.
Actually, I think this interpretation is too fair. These days scientists
confuse their papers with journalism: their conclusions are sensational
not original. With the need to attract money for research in biology,
this trend is increasing. The class-act is someone who has original
conclusions in their papers but knows how to regurgitate them for
popular consumption.
First point, Tyler's information is not much on from Covacevich and
Michael Archer's seminal 1974 paper on death and poisoning of native
animals by introduced toads.
Second point, I think there is something in that about animals that can
teach their young, or each other, passing on information about "good
manners" when eating toads. This conclusion comes from experience of 25
years with public inquiries. A recent example, it has only been in the
last three years that people have been noticing Torresian Crows eating
toads by breaking through the abdomen and eating the guts. First there
was, one report, then there were a couple of reports - then an
avalanche.
That young can be taught might be more so with birds with precocious
young. An example, as a kid growing up in Innisfail, north Queensland, I
use to run around our yard chasing our domestic Muscovy Ducks. They
would flip toads over, push their bills into the abdomen, then open
and shut them rapidly, break through the skin and muscle, and then eat
the toad's innards. (I was chasing them because I thought toads were
native frogs! It broke my heart when I found out). Yes, it would be good
to ask someone who might know, "Do they do it in the wild." Or did our
domestic ducks learn in our backyard and pass it around.
As well, I have watched swamphens around the University of Queensland
lake (when there was one only) grab a toad in one foot, lift the
amphibian towards its bill then ram its bill through the toads mouth,
eviscerate it, eat the guts and drop the husk. The question is here, "Do
they feed on native frogs by eviscerating them?" (Once saw a swamphen at
Bunya Park Zoo - in the kiddy's Old McDonalds Farm area with the cute
animals - snatch a guinea pig and fly off with it, leaving behind many
distressed patrons).
As to Black Kites, I do not remember them taking toads, or their
carcasses, when I was young. As said before, one is diurnal and the
other
isn't. As well, even though kites are among the first scavengers along
roads at first light, they have often been beaten to squashed toads by
giant centipedes, which drag the carcasses off the road. (In Micronesia,
hermit crabs replace centipedes as the amin road scavengers of dead,
introduced cane toads).
For Fork-tails, it would be interesting to try and conclude if this is a
recently accessioned behaviour. It is certainly the first time I have
heard of it. We need a good study on the anecdotes. It would be
worthwhile. So many people are toad-conscious and watch what happens
with them. Then we need someone to check the folk-knowledge...
Glen Ingram
Brisbane, Australia
"Cauliflower is nothing but cabbage with a college education" Mark
Twain.
WM James Davis wrote:
> > On Thu, 19 Jun 1997, Alex Appleman wrote:
> >
> > > Following on from Shane Raidal's commemts; raptors are hardy
> critters and also
> > > intelligent. There is evidence in North Queensland of black kites
> preying on
> > > the dreaded cane toad, flipping them over and feeding the legs and
> soft underbelly to their chicks, avoiding the poison glands. We can
> only assume that the kites ate poison in small doses, identified which
> part of the toad was toxic
> > > and are teaching their offspring how to avoid them.
>
> Taylor writes:
> >
> > There is a summary of what is known about Cane Toads's effects on
> > the Australian biota is a chapter in Mike Tyler's Australian frogs.
> > He notes deaths of Kookaburra, a Crow species and two Bittern
> > species as recorded as being killed by eating Cane Toads.
> > This list probably reflects most the poverty of the data that
> > Tyler could find.
> >
> > He also notes a number of bird species recorded as successfully
> > preying on toads including Tawny Frogmouth, Whistling Kite,
> > Ibis, Cranes, Swamp Hens and Herons.
> >
> > Mike Tyler also notes some native frog species posssess poison
> > glands and native predators avoid these.
> >
> > So some possibilities are:
> >
> > a) Black Kites pre-Toad feeding techniques don't expose them to
> > much toad toxin. Certainly if they don't tackle live toads their
> > risks are reduced.
> >
> > b) Black Kites could (pre-Toads) detect and avoid the toxins. Cane
> Toad
> > secrete cocktail of chemicals. Some of these chemical are only
> found in
> > toads but perhaps Black Kites already could detect and would avoid
> > one of the cocktail components.
> >
> > c) Black Kites have (pre-Toad) techniques for eating poisonous
> native
> > frog species which have also allowed them to eat Cane Toads.
> >
> > d) New techniques were "discovered" by Black Kites (or other
> raptors)
> > which allow them to eat toads and these have been communicated by
> > observation among Black Kite populations.
> >
> > e) Immigrant Black Kites from Asia where Bufo species are native
> > have brought suitable toad eating techniques to australia
> > and these have been communicated by observation
> >
> > f) Black Kites (currently) eat Cane Toads and die and no one
> notices.
> >
> > I don't want to seem rudely skeptical but there are lot of claims
> > about Toads but very little data.
> >
> Jim's Comment:
>
> Thanks for the info. and in my opinion you are not being rude -- it
> is
> enjoyable to learn about what facts are available. And, I would like
> to
> add I am please that Alex brought up the issue of kites eating toads
> in
> the first place. Now, if I may be so bold to add my two cents:
>
> 1) Given what you have stated about the toad eating habits of the
> asian
> sub-species of Black Kites then we can expect that the Australian
> subspecies would be pre-disposed to switch to eating cane toads once
> the
> toad population reaches a high enough level. But, I wonder aren't cane
>
> toads essentially nocturnal and kites diurnal?
>
> 2) Several other behavioural factors might be relevant. Alex's
> comment
> about young kites being taught to catch toads may have merit given
> that
> Black Kites are highly social for a raptor species. According to
> statements in Penny Olsen's book on "Australian Birds of Prey" the
> "gregarious" black kite travels in "small flocks, seldom singly, and
> is
> one of the first raptors to arrive at fires" toeat carrion. If so,
> this
> is where and when Kites could be introduced to the habit of eating
> toads
> -- first dead ones then live ones followed by parents teaching young,
> etc.
> However, it is my experience that young birds are more exploratory and
>
> consequently, young are more likely to sample new foods than are
> adults.
> Is true for raptors such as kites? I have no idea.
>
> 3) This arrangement would be ideal for the study of the cultural
> transmission of a new feeding behaviour in a wild population. I know
> there are people tracking the spread of cane toads into the Northern
> Territory and these data could be used as a baseline to calculate toad
>
> abundance.
>
> I better stop here, I am getting a little out of hand <grin>.
>
> Cheers, Jim
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