
Pioneering study finds more than 200,000 rats in Barcelona’s sewers - dgarceran
https://elpais.com/elpais/2018/09/19/inenglish/1537368873_338066.html
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Tharkun
200k doesn't seem like that much. Rats aren't very big, and Barcelona is a
pretty large city, with a population of about 1.5M humans. I would have
expected more, having grown up in a rural area where there's a lot more mice,
rats and other critters than one per 7 humans.

~~~
Retric
A city’s aewers are tiny relative the city’s area. Parks, Apartments, etc are
all going to increase the city’s rodent population.

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interfixus
Leaving aside the pest aspect (and I'm sure it's all too real in many places),
rats are fascinating creatures with a sharp, pragmatic intelligence, loads of
adaptability, and social behaviors that we primates can very easily recognize
and relate to. I have seen rats perform clearly abstact thinking, brewing up
complex ad-hoc plans, and show stunning degrees of spatial awareness. I have
been lied to by a rat, who seemed to have worked out a decent model of my
expected behavior. Which I promptly delivered - the rat won. And these were
domesticated rats. I should be surprised if their wild cousins weren't up to
even more hardcore mental trickery.

~~~
majos
> I have been lied to by a rat

...elaborate?

~~~
interfixus
Rat teaches me to feed her when she tattles her tray. But I won't do it until
everything's been eaten, also the boring bits. Then suddenly for weeks no
trouble whatsoever - when she rattles her tray, it's empty, everything gone.
Until one night, hidden behind a doorpost, I watch her methodically clean out
the boring bits and bury them under floor pellets. As soon as the tray is
empty - rattle rattle rattle. This was a supremely gifted individual. She
performed similar strategems towars her cage-mates, for the most part
successfully.

Oh, and I always wondered what all the fuss was about with the Japanese
macaque monkeys and their cultural transmission stunt. I saw one rat getting
inventive with the drinking water tap, beginning to take water with cupped
paws and use it for washing her fur. Others picked up on that habit, and yes,
it spanned generations.

~~~
tetrep
How do you know it's deceit? It seems like you could get similar behavior if
you filled two trays, one with food and the other with trash, and never
provided food unless the trash tray was empty. You're training the rat to
empty the tray.

~~~
interfixus
Not quite. She realised I could be tricked, but only if she thorougly covered
her traces. I watched the thing. It was so clearly reasoned behavior.

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barking
This reminds me of the saying _" You're never more than 6 feet from a rat"_

[https://www.bbc.com/news/magazine-20716625](https://www.bbc.com/news/magazine-20716625)

~~~
josefresco
Neat article, for those looking to save a click:

"Urban areas in the UK cover around 16,000 square kilometres. If we distribute
the rats evenly across the urban areas, which is clearly unlikely but
necessary for the calculation, each rat has a rather spacious 5,000 square
metres to roam around in.

Assuming you're standing at a given spot in an urban area you would be at most
164ft (50m) away."

~~~
tomarr
"Assuming you're standing at a given spot in an urban area you would be at
most 164ft (50m) away."

Not sure how they maintain a population if they remain 100m away from each
other

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albertgoeswoof
At most not at least

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onetimemanytime
I lost count after 200,003 rats :)

Do rats serve a useful (for us) purpose there? If not, can we release a rat
specific poison or is that impossible without harming the entire ecosystem?

~~~
zimablue
[https://www.theverge.com/2015/5/13/8592817/rat-patrol-new-
yo...](https://www.theverge.com/2015/5/13/8592817/rat-patrol-new-york-alberta-
canada-south-georgia-eradication)

The guys who do this professionally/successfully in a sparsely populated place
with everyone helping and the advantage that rats can't survive outdoors don't
think it's possible in cities.

Big problems with poison: Rats are harder than you think to poison, they're
both sceptical of new food and adapted to survive lots of poisons Evolution
will work against you and select rats that don't eat or digest your new poison
You will poison lots of things you don't intend to (wild animals, pets,
humans).

You can imagine an IOT solution in 50 years though (coordinating web of
mechanical cats/ferrets with amazing smell/sight that just never stop
hunting).

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adrianN
AI gun turrets in the sewers.

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Idontagree
Off topic, but you really think there arnt automatic turrets, seems very
feasible today, especially in a situation like a sewer where you really dont
have to worry about shooting the wrong (moving) thing.

~~~
adrianN
We had automatic turrets decades ago, so the "AI" part was just me trying to
be funny.

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Schiphol
A bit of context that is perhaps relevant. As some of you know, there is a
political conflict between the central government of Spain and the local, pro-
independence Catalan government. El País, a newspaper published in Madrid, has
quite explicitly taken the central government's side a few times. I wouldn't
be terribly surprised if this bit of news was singled out for publication
because it's about there being potential health and safety issues in the main
city of Catalonia.

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franze
currently one 0 missing in the title (200 000 not 20 000)

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xevb3k
I thought 20,000 seemed way to low, given the human population of Barcelona is
1.6 million.

200,000 still seems low. I wonder what fraction of the rat population lives
outside the sewers.

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afturner
This is interesting, but is it really Hacker News-y? Regardless, thanks for
sharing :)

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dang
Of course it is! 'Interesting' is the key criterion.

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

