
Torresian crows have learned how to make a meal of cane toads - fern12
http://www.australiangeographic.com.au/topics/wildlife/2018/01/can-crows-eat-cane-toads?utm_source=Sailthru&utm_medium=email&utm_campaign=AG%20Newsletter%2030/01/2018&utm_term=list_australiangeographic_newsletter
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interfixus
Crows are a constant source of amazement. The last couple of years, we have
watched our local population take up the practice of crushing walnuts under
moving carwheels. I know this trick is performed with high levels of
sophistication in many parts of the world - nevertheless, it has been
fascinating to see this new behavior take hold and spread among the many, many
crows in the region. It's hard not to fancy a pair of disapproving corvid eyes
boring into you whenever you've let your instinct take over and have swerved.

Actually, I'm getting more and more into the habit of _not_ swerving. For
everyone else, absolutely, but not really for the crows. They have my vector
to any number of decimal points, and will nonchalantly hop out of harms way at
the last possible moment - often into the opposite lane, if no oncoming
traffic is seen there. We _never_ see them as roadkill. Pheasants, gulls,
sparrows, what have you, but never the crows.

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logfromblammo
I imagine Aussies could make a bigger dent in their cane toad problem by
giving some smart folks a budget to teach classes and produce educational
videos specifically for crows.

Spread the knowledge on how to safely eat cane toads to every corvid on the
continent, much faster than that information could spread naturally.

Some crows have a concept of death and mortality, and the ability to make
causal associations. It is certainly possible to teach them a skill by literal
demonstration, and may be possible to teach via symbolic representation.

Catch a bunch of cane toads. Prepare the edible parts from some as
motivational snacks to attract interested crows. Use a crow puppet to naively
eat a model cane toad, and make it "die". Then use another crow puppet to
manipulate and eat a model toad avoiding the poison glands. Give a live cane
toad to a crow known to have the skill, so it can demonstrate. Then release
some live toads for novices to try it out.

Then attempt an experiment to show a video of that demonstration to an
ignorant flock, and see if they can acquire the skill that way.

~~~
XR0CSWV3h3kZWg
It'd be a very interesting experiment to figure out how to effectively teach
wild crows new skills.

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overcast
Clever crows, but a real shame other predators are being killed off because of
their unfamiliarity with an invasive species. I wonder if any naturally immune
individuals will rise up from the loss of their main populations.

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daveguy
More likely some of those predators will learn to avoid them rather than
become immune to their poison. Hopefully they will learn that before they are
reduced to unsustainable levels.

~~~
overcast
Do most animals have that ability though? How do you learn from something when
you're dead from it nearly instantly? I don't think snakes have knowledge
outside of instinct. That's the point of this crow article.

~~~
tialaramex
Natural variation and selection. (Biological) Evolution changes populations,
not individuals.

Suppose there's one snake that is genetically disposed not to eat toad-shaped
things, frogs, cane toads, anything like that, the same way I don't like nuts.
They're not toxic to me, I could eat them, but I don't. Previously toads
weren't toxic to snakes, but that snake didn't eat them.

Normally that snake has a small disadvantage, other snakes eat toads and it
goes without. Too bad. But now it won't get poisoned. This means it's slightly
more likely to survive to adulthood, breed and produce more snakes.

Further genetic changes to avoid toads will also be selected for in the same
fashion.

This process is very slow in multi-cellular creatures, but it does exist. It
may not be fast enough to adapt to the cane toad of course.

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notheguyouthink
Appreciate your comment. It always impresses me how many people misunderstand
the _(what I feel to be)_ basic concepts of evolution. I'm not educated on the
matter either, mind you - I'm sure I'm very ignorant on many aspects of it.

Regardless, it always makes me wonder how much the anti-evolution "movement"
would be affected if people simply had a better grasp of it.

~~~
kbenson
Quite a bit of the provided possible outcome rests on likelihood of certain
genetic factors and, relative size of snake population, and how quickly cane
toads spread.

The actual values of these variables (and a few more I'm sure) can change
whether one population dies out or not and how quickly. Just because evolution
provides a solution to the _general_ problem, doesn't mean there's a solution
that saves the population when the _specific_ problem is looked at in detail.
Invasive species cause local extinctions all the time.

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toxicFork
I recommend this excellent and hilarious documentary if you'd like to find out
more about cane toads:

> Cane Toads: An Unnatural History

[https://imdb.com/title/tt0130529/](https://imdb.com/title/tt0130529/)

(I have found versions of this on YouTube, but unsure how legal they may be)

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oldandtired
In some respects, if human development followed the cane toad, we would become
virtually indestructible. As children, we would use them as cricket balls and
some would still hop away afterwards. We found that inserting lit penny
bungers into them was an effective way of terminating. Freezing them was also
effective, but your mother tended to object to them being in the freezer.

What was disturbing about them was the size that some would grow to. I
personally have seen one that was about 20 cm (8 inches) high. I have heard of
them being much larger.

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mkoryak
I feel bad for those frogs. Imagine being eaten/beaten for 40 minutes by a
crow. Probably left to slowly die after it is done eating you.

And the crows friends are watching the whole time too.

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jimmywanger
Cane toads are an ecosystem destroying highly invasive introduced species.

The crows are doing our work for us. The method might be messy, but cane toads
should be exterminated in non-native habitats as expediently as possible.

Instead of feeling bad for them, why don't you feel bad about the species they
have almost wiped out?

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grasshopperpurp
You can feel bad for the toads and the species they are wiping out. It's not
like they are consciously deciding to be an invasive species.

~~~
jimmywanger
I feel bad for the native species. Cane toads are prolific throughout the
world, and they've driven many species to near extinction.

At some point you have to decide what your priorities are and start culling.
E.g. Australia wants to kill 2 million feral cats over a decade, as there are
30 million of them, and each one kills 3-20 native animals a day. [0] At some
point you have to make decisions and decide which is more important. If you
could teach crows how to eat cats, Australia would like to have a word.

[0] [https://news.vice.com/article/feline-massacre-australia-
unve...](https://news.vice.com/article/feline-massacre-australia-unveils-plan-
to-kill-two-million-feral-cats)

~~~
meric
It's OK to kill an animal and feel bad for it at the same time.

~~~
lawlessone
crying onto my bacon.

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ivanhoe
These frogs are really strange - usually poisonous animals have some way of
clearly showing not to mess with them: bright colors, smell, sounds they
make...

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IntronExon
They’re stealthy hunters, so bright aposomatic coloration would be
counterproductive. I also believe that there is some aposomstic scent markers
and behavior in the case of cane toads, it’s just that native Australian fauna
has taken time to adapt.

[http://www.pnas.org/content/101/49/17150](http://www.pnas.org/content/101/49/17150)

They’re not “learning” to avoid, but selection pressures are having the same
end result.

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MarkMc
Reminds me if this joke from QI, the UK TV show:

"Australians have a big problem with cane toads. They have a foul odour and
spread like wildfire. And they have a big problem with cane toads."

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jxramos
Seems to be a handful of videos on YouTube of this phenomenon. A bit in the
gruesome direction as a warning to others
[https://www.youtube.com/watch?v=7lWX5x0Kmgs](https://www.youtube.com/watch?v=7lWX5x0Kmgs)
There's a few videos posting about the phenomena from 6-7 years ago so
apparently they've learned this trick for some time.

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joshwa
"During much of this process other crows stood and watched."

    
    
      EXT. A FIELD OUTSIDE BRISBANE - DAY
    
      CROW 1: I dare you to eat that poisonous frog.
    
      CROW 2: Hold my beer.

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FuckOffNeemo
I'm from Brisbane, I'm going to start paying more attention to Colin the Crow
who frequents my back yard with a little more care.

At this present moment he's helping my house mates chicken finish her
breakfast.

Day 1 Colin seems to be a chicken in disguise

