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The vultures of Spain skirt around the Portuguese border with uncanny accuracy (twitter.com)
542 points by isp 14 days ago | hide | past | web | favorite | 101 comments

The way everyone is writing this off as so obvious is annoying. Have you guys never found a bug that in retrospect was glaringly obvious, but all the symptoms looked bizarre until you found what made them all connected? This is a fun story the same way the "500 mile email limit" story is a fun story. Yeah the idea of "your timeout is so low that it times out unless you're sending a very local request, about 500 miles" is obvious and somewhat boring in retrospect too, but that twist is what makes them both fun stories/facts.

I actually find the story very interesting. I'm curious about one things: do vultures actually learn the geography, presumably from each other and not direct experience? Or are they following concentration of some carrion-related volatiles - i.e. turning around where the air stops smelling tasty? I know next to nothing about these birds, but I'd find the latter more plausible than the former.

They might be using both! Studies on homing pigeons [1] have found that they use atmospheric volatiles to navigate until they're in the vicinity of their home region, at which point they use landmarks (like roads or field boundaries) to navigate. So it's possible that vultures have learned that the air on this side of the river smells better than the air on that side of the river, and therefore know to turn around when they wander across.

[1]: http://theconversation.com/explainer-how-do-homing-pigeons-n...

Thanks! Good to know this happens. For some reason I haven't thought about birds using sense of smell until today when writing the previous comment.

Actually, this reminded me about the impact pesticides etc. have had on Parsi death rights in India. Parsi people rely on birds of prey to consume their dead bodies in Dakhma's (structures intended for dead bodies to be exposed to birds that consume carrion). Due to the destruction of the population it's basically become much more difficult.

More to read here if interested - https://en.wikipedia.org/wiki/Tower_of_Silence#In_India

I think you probably meant "death rites" (not "rights").

Presumably they have rights to their rites.

That is a fairly strong assumption for a good chunk of the world.

About a decade and a half ago CCMB (Center for Cellular and Molecular Biology), Hyderabad actually bred vultures for this very purpose. I don't remember if they ended up solving it.

I understand your sentiment, but this plot twist was much less clever than the 500 mile email issue. My immediate thought was this was due to geography (natural or man-made) or laws/regulations that protect their habitat or food sources.

There is a word/name for that phenomenon though it escapes me right now. That said, in this case I think many/most people assumed the correct answer (or something close to it) prior to the grand reveal.

Hindsight is 20/20?

Reminds me of this explanation of why during the 2012 election, Obama won the counties where the most prehistoric plankton had died: https://www.npr.org/sections/krulwich/2012/10/02/162163801/o...

In short: plankton -> fertile soil -> cotton farms -> slavery -> African-American votes.

In case anyone is interested

Great Big Story: The Vultureman of Spain (3m14s)


"Manuel Aguilera wants you to know there’s no reason to fear vultures. The ornithological guide has gone as far as climbing into an animal carcass to get closer to the birds of prey. He’s spent 40 years studying the griffon vulture, and has dedicated his career to changing peoples’ perceptions of the birds, hoping to have others realize that they are majestic creatures to revere and protect."

Knowing they are scavengers I would not be afraid of them, by the time they bother you you will be dead. They won't attack anyone who has any way to defend themselves.

> you will be desd

our dsying …

We fixed the typo.

I have seen elk wander back and forth across an invisible boundary all year, but the first day of hunting season you can bet they will not put one hoof into the game unit.

As mentioned elsewhere in the thread, the behavior has nothing to do with knowing a border but rather something important to vultures: lack of carrion on the other side because people on the other side observe different laws pertaining to animal disposal.

Right, that's their point: game, elk/deer/moose, will avoid areas where there are active hunters and seem to have a sixth sense about where those boundaries are, for instance retreating to game preserves on the first day of the hunting season for similar reasons to why the vultures respect borders (prey vs. predators)

>[...] for instance retreating to game preserves on the first day of the hunting season [...]

I doubt that animals can tie obesrable phenomna (eg. lunar cycles or solar azimuth) to a human calendar date with day level accuracy, because of how small the differences between each day is and how arbitrary the human calendar can be. It's much more likely it's due to human activity such as increased traffic noises/gun shots on the start of the hunting season.

Birds migrate seasonally no reason an elk can't learn the need to migrate. Perhaps"day one of hunting season" is hyperbole but the jist may be true.

They hear/smell the hunters, thier trucks, and thier dogs. When a unussual number of pickups start driving into the woods at 5am, it is time to retreat.

Probably other indicators, like the sounds of trucks, smells of gunpowder, etc.

Day one of hunting season is when the hunters enter the woods and start hunting. I’m not saying they migrate to safe places the day before.

The farmers aren’t targeting vultures directly.

I mean the title is akin to saying “Starbucks uncannily observes landmasses when putting in new stores —they haven’t been observed to put them in the middle of the ocean (barring cruise ships). Or “Lions avoid the actual Sahara desert”.

You're missing the point. In both cases, the animals are respecting invisible borders, in one case because there is no prey on the other side and in the other because there are predators on the other side.

It's similar, not exactly the same, and respecting the invisible border is the point.

I think they adhere to, rather than respect, the border.

I think much of the explanation for animals like elk is that they just shy away from humans on foot. That activity increases lots during hunting seasons.

Where I grew up in Sweden, the moose will be pretty much fearless nowadays. Last summer, one was standing not three meters outside my window, staring at me. A few years ago a cow and her calves would stop by the road, and look curiously at us in- and outside the car, while moving nearer, not further away. Not in a threatening way, nota bene. There are also people walking dogs, picking mushrooms, tending to forest and fields, etc.

Still, when hunting season is afoot, they are always somewhere else. I know of one of their hiding places in particular, a small but shielded patch of forest where you can't shoot.

It's not surprising--they are being hunted--but it's not the same behavior as when it's people without guns, outside of hunting season.

Would be interesting to learn what triggers this behaviour.

People suddenly bantering through areas that normally are left alone? Seeing rifles? Sounds of shooting?

I think prey animals have a sense of when a predator is actively hunting vs. just happens to be in the area. Humans kinda act like cats when hunting, walk very low and quiet, use cover for concealment, frequent hard stares, etc. Humans just out for a hike do not act like that.

It's also possible that they can recognize some human equipment, and shy away when humans with guns start showing up.

A good example along those lines is Gunnison's prairie dogs. They have a variety of warning calls for different dangers, and they also have modifiers for some of them to better call out what they are warning about. For the warning call for intruding humans, they have modifiers based on the colors of the human's clothes, and based on whether or not the human has a gun.

I wonder if elk are smart enough to pass along the word that the humans with guns are around.

Here's a few links about these the prairie dogs and their communication:





I used to live in a small mountain village in the US, in the middle of a wilderness area. A mile or so around the village is not considered wilderness, and hunting is banned there. It's the largest group of people for miles and miles but the deer have no compunction about coming into the village. They even tend to come there to give birth. They know the hunters don't hunt there.

I once saw a nursing deer lead her fawns into an active shooting range in midsummer. Everyone had to stop shooting and watch them play around the targets. This occurred in an area where it was only legal to hunt them in autumn and winter.

They somehow know that we humans become murderous but are safe at other times...

It's funny because they even avoid Olivença, which is De Facto in Spanish side of the border but is disputed.

Vultures knows what country it should belong to \s

I googled this because if your comment and found out about the sovereignty issues. I had never heard about this conflict in my life.

I guess if I was to ask the average Brit about the sovereignty conflict with Spain regarding Gibraltar they would probably be non the wiser...

There are a few others in Europe, in particular the Mont Blanc. Though in practice, it doesn't affect day-to-day life.


10/ It's not just vultures at stake: the collection, transportation and disposal of dead animals is costly and polluting.

Maybe Tibetan Buddhists, who feed their dead to vultures as a form of burial, are on to something.



I wonder if, given enough distance, this is actually a really good way to avoid deceases.

Burying or burning is a good "rite" or meme, that will avoid many deceases. In the way that it favours cultures who dispose of their dead this way, have a benefit over those who leave them "lying around", so to say.

Would a sky-burial work similar? Or does that simply spread the risk of contamination over a large area that it only helps cultures in really sparse areas?

Vultures play a critical role in disease control and waste removal. They are actually one of the most important scavengers in Africa and are believed to consume even more carrion than mammalian scavengers like hyenas. Vultures also eat rapidly and feed in large groups which allows them to consume carrion quickly. This reduces the risk of disease spread from flies or bacteria. Vultures are resistant to many diseases so they don’t contract or spread diseases like tuberculosis or brucellosis even if the animals they are consuming died from those causes.


I think the funniest part of this story is how much Portugal spends on the corpse removal & burning. The vultures do the job for free!

Another example of this is in The Biggest Little Farm. The farmers have a problem with gophers. The "traditional" ways of handling gophers are all very expensive or have bad side effects. They figure out that if they attract owls to their farm by building owl houses, the owls take care of the gophers.

Both of those are good examples of letting nature work for you, rather than you trying to work against nature. For humans to have a sustainable future for tens of thousands of more years, I think we need to figure out how to work side-by-side with nature rather than try to bend nature to our will.

I think there is some historic background here as well.

You had brucellosis scares in Portugal with a lot of media coverage, which lead to quite a few human brucellosis cases and several sheep and goats exterminated in containment measures.

I have no evidence that these are related but the corpse collection could be an over the top measure by the regulatory authorities to stop brucellosis disease vectors.

It reminds me of an article posted on HN a while back [0] about how zebra mussels have helped clean up Lake Erie. It's written by a modern druid, who laments that humans so often avoid the ecological solutions mother nature has provided us.

[0] https://news.ycombinator.com/item?id=20359876

> zebra mussels have helped clean up Lake Erie [...] modern druid, who laments that humans so often avoid the ecological solutions mother nature has provided us.

Zebra mussels are an invasive species that were transported to Lake Erie (and the rest of the Great Lakes) via unnatural and unintentional methods. They also make murky water more clear which does not have anything to do with how clean or healthy a body of water is.

They're more like cane toads in Australia than the restoration of the wolf population in Yellowstone.

But apparently they make for bigger salmon in Lake Ontario https://www.npr.org/templates/story/story.php?storyId=878434... ¯\_(ツ)_/¯

Beware the unintended consequences. Australia is still ruing the introduction of the cane toad, which was introduced to the country as a biological control mechanism.


And then birds and fish eat the dead zebra mussels and die of heavy metal poisoning.

It's a solution, but it's not a very good one.

I doubt that clogging our drinking water pipes and blocking the refrigeration system of electric and nuclear plants would count as solution by modern non-magical people.

Often less is more. One might say, let the animals work!

Nature's solutions and systems are almost always the most efficient, whether regarding to energy, time, or health.

From the thread: "Representatives of BirdLife International, a nature conservation partnership, in both countries argue wildlife will benefit from the integration of sanitary policies across European borders." ...but I was thinking the exact opposite. Because at least they didn't have BOTH countries doing this, the vulture population can survive in decent numbers on the Spanish side, and whenever Portugal comes around the vultures will figure it out and come back. But, if Spain and Portugal had both, for years, reduced the supply of food available to vultures, the population would have either died off or had to move much further away.

Sometimes, avoiding a big mistake everywhere is more important than avoiding a big mistake anywhere.

Talking to a foreign ATC is just too much of a hassle... :-)

"The vultures of Spain skirt around the Portuguese border with uncanny accuracy" is a stunningly dishonest way to report this. Based on the pictures supposedly supporting this headline, which open the thread... if you had the vulture data and didn't know where the borders were, you would be totally unable to guess where the borders were.

Rather, most of Portugal is included within a larger region where vultures mostly don't go, because they can't find food there.

Portuguese farmers don't bury dead wild animals, so obviously there are vultures in Portugal too.

Maybe there are too many vultures in Spain because of the unnaturally abundance of dead cattle, just a thought.

Also, it's nice to be an arm-chair environmentalist as long as that dead cow isn't rotting next to your house.

> Maybe there are too many vultures in Spain because of the unnaturally abundance of dead cattle, just a thought.

Pasture lands decrease habitat that would support the wild animal populations that would normally feed the vultures. Are you aware of any numbers indicating an unnaturally high vulture population?

> Maybe there are too many vultures in Spain because of the unnaturally abundance of dead cattle, just a thought.

Nobody is trying to make the removal of corpses from inappropriate places illegal. They are trying to make it legal to leave some corpses in place.

> Maybe there are too many vultures in Spain because

Because good and hard work

In Spain there is a recent strong culture of protecting this birds, as result of the work for the last decades of several spanish associations like Fapas, Seo Birdlife or Grefa.

And because money

The farmers in this places are supposed to pay for removing dead sheep and cattle corpses by law, but they often pretend that the cattle was lost, look to other point whereas the vultures do the job for free and save the money.

According to the series of tweets under discussion:

6/ A handful of nesting colonies remain in Portugal, says Joaquim Teodósio, a biologist working for the Portuguese Society for the Study of Birds (@spea_birdlife ), but the vultures that occupy them spend the daylight hours abroad.

Also, it's nice to be an arm-chair environmentalist as long as that dead cow isn't rotting next to your house.

The person writing these tweets in English has a Spanish language description in their profile that says in part (when translated):

Science and environment journalist. I studied biology and scientific communication.

(According to Google translate)

1) Agree, is a clear anomaly

2) Vultures DO cross frontiers and the map clearly show this in two points.

This is the expected output because vultures travel far between two points, and in some places the shortest path from points A and B in Spain is through Portugal

3) I would not discard an artifact. I don't know the specifications of the procedures but I wonder if this could be just a technical problem, bad signal in one part of the map, stronger repeaters in the frontier picking or masking signals on the other side, etc...

This subthread made me smile - and then think:

Krishna Shamanth @KrishnaShamanth

Apr 9 I've seen them vanish.. Very sad.. Whenever I visit a village, I look for vultures... Nowhere to be seen... I guess they all reborn as govt employees of some divisions and politicians.

Lizanne Whitlow @LizanneWhitlow

Apr 9 The cleanup crews are very necessary in our world

Well given than in Spain vultures are feeded by the remains of butchers, while in Portugal those remains are burned down(I believe), it is not a big surprise.

I have seen them being feeded in mountains at the north of Spain called Picos de Europa: https://en.wikipedia.org/wiki/Picos_de_Europa

Laws change abruptly across boundaries, so it is not a surprise that vultures know when they are feeded or not.

Birds or animals are not stupid. Animals that are hunted know exactly when the hunting season starts and ends. I have seen deer separate in sexes when the hunting ban expires(because the law forbids females to be hunted down), so you will see females with offspring completely relaxed in front of people.

> Spanish farmers don’t collect dead cattle, but in Portugal, they must bury or burn all carcasses. This leaves no food for vultures, who have learned that the grass is always greener on the eastern side.

Case closed.

Why? What's the genesis of this difference? Does it have a tie-in to, say, a famous public health crisis? Who says there are no vultures on the Portugal side? Where can I learn more, if I want? Who works on this stuff? Pictures?

The short-form summary that provides this requires the same number of clicks to reach from HN as your comment.

What? Click the link and scroll down - it answers this question.

I won't enable you with an answer here, but it is a very interesting answer :)

You should re-read my comment.

Your comment had put the punchline at the end, instead of the beginning, which is almost the same issue you're complaining about in the comment. Not only do you point out the issue with words, but with form as well. :)

"Why is the comment so long? Why did I have to read to the end to figure out what your complaint was?"

I think jcahill's complaint is that pier25's quote leaves out important details, and the original thread is short enough to read.

All he's saying is: the tl;dr is not significantly shorter and is missing interesting information. Some serious miscommunication going on here.

jcahill 13 days ago [flagged]

Do, uh… do you tell jokes with the punchline at the beginning?

Spanish farmers must do call authorised vets for removing dead cattle, by law. Laws among both countries are not so different, but this is non relevant. We are chasing a macguffin in my opinion...

... because the real culprit is probably not cattle but deer.


vultures distribution overlap with deer distribution. Here you have the solution to your mystery, Bruno.

Thank you so much for this tl;dr! I wish all eye-catching articles were similarly summed up in one caption and/or image.

This kind of attitude is what leads to people using Facebook memes to inform their entire worldview. The whole Twitter thread takes, what, 1 minute to read?

You definitely can not say the same about Canada geese :)

Fun fact: they're actually called "Canada geese", https://en.wikipedia.org/wiki/Canada_goose.


I always thought they were New Jersey geese. That's where most of them live.

Could the fact that the Spain/Portugal border is influenced by geography also be a major factor? Both the border and the birds' flight patterns are likely heavily influenced by geography

It's not just the first tweet, read the whole thread.

> The Portuguese-Spanish border follows river valleys and is not associated with abrupt changes in climate or land-use.

> The reasons for the mismatch are historical. In 2001, Europe’s answer to the mad-cow disease (BSE) crisis was banning the abandonment of dead livestock. [...] [Conservationists] convinced European Union legislators to delegate the choice to member states. Some countries, like Spain, resumed cattle abandonment under special conditions. Portugal never changed its laws.

No matter what the story is, someone will always post the comment "In other news, water is wet" or "No news here, this has been known for 10 years" or something to that effect.

All bugs are shallow given enough eyeballs, I suppose.

Yeah, any old vulture could have told you about this.

This comment is of a similar nature, I feel.

Apparently, "vautours sans frontières" is not a thing…

Half of the comments: low-attention, high-misery demands that an already short summary of an interesting phenomenon be shortened to the minimum number of words possible, presented like it's not worthy of arousing your curiosity.

The other half: people who didn't read the link providing baseless conjecture.

Good stuff. Curiosity bad. 200-comment threads about minor releases of enterprise middleware only.

Alas, comments like this one perpetuate the problem you're complaining about, actually in a worse way because second-order phenomena are harder to deal with. For example, low-value dismissals tend to get downvoted and supplanted by better comments. But indignant meta-rants tend to get upvoted and sit at the top of the page, giving off fumes. That's where this one was until I marked it off-topic.

Believe me I understand the annoyance of bad comments and shallow dismissals, but trying to fight them this way just makes the threads worse.

Now there's simply another meta comment at the top. When you mark that one off-topic, an irrelevant anecdote about elk that suggests possibly-not-reading-the-article will be on top.

That comment does start out with a meta criticism, but then it turns into a much better comment by saying something fun and interesting about the article, which gratifies curiosity in its own right.

The one about elk isn't irrelevant: it describes a comparable situation. Better still, it's based in personal experience. Anecdotes are fine—they're the life-blood of good conversation, and HN threads are supposed to be good conversations [1]. We're not doing peer-reviewed replication here.

That's perhaps the real problem with the comments you've been posting in this thread: they're bad for conversation because they're bilious. Bile is a bummer.

1. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

I was about to follow up my meta comment with a regular comment about river basin mapping and bird migration viz until your reply about the off-topic flag. Defense of curiosity for its own sake is a preface for conversation.

Noting disappointment in people being miserable about something interesting, which in itself totally disinvites on-topic conversation, isn't bile. I can't ask people to read the article per the site rules, even though it's painfully apparent that half the problem is lack of nudging to read the article. So of course dissent is going to be colder than it could otherwise be.

> a regular comment about river basin mapping and bird migration viz

That sounds great! That's the way to combat bad comments, by posting better ones. I'm sorry if I put you out of the mood for that. Please reconsider?

I gotta say, I agree with you and it looks like they're mostly going to get buried and flagged dead soon.

But doesn't this comment just do the same? Like, for a top level comment it is even less about the article.

Replying so negatively to a particular comment when it's meta about the thread in general wouldn't have made much sense. HN's taboo against asking people if they've read the article is also wildly outdated -- its readership is too big and broad for the underlying assumption about tact being discursively superior to directness to hold. So you have to outright tell people they haven't read the article, when it's very apparent that they haven't. It's frustrating.

Ah, click-bait in 280 characters?

TL;DR (or "A lengthy summary posted using Twitter's clunky 'thread' feature; didn't read"): Portugal has laws that require farmers to dispose off their dead cattle, Spain doesn't.

According to your definition of click-bait title, I would say that almost all the human literature would be "click-bait".

That's not true? The "traditional" essay begins with a topic paragraph and a thesis statement, with later paragraphs supporting that assertion.

Only new-form, gotta-read-to-the-end journalism hides the interesting lede at the end.

n=11 for one figure, n=60 for the other.

Many borders follow natural features like say a mountain ridge, and such features affects air movement patterns, humidity/clouds, etc.

The article points out that this is NOT the cause. The border between Spain and Portugal crosses all sorts of divides and watersheds: the Tagus river starts in Spain, passes near Madrid, travels west, and empties into the Atlantic in Lisbon. In fact, 3/4 of the Iberian peninsula has rivers that feed the Atlantic, and the divide between rivers that feed the Atlantic and those that feed the Mediterranean is way on the East side of Spain, far from the political border with Portugal.

If you read the tweets, you're in for a big surprise!

Vultures can fly over the border but their nests and young offsprings can't. Maybe this small restriction got some influence over their flight patterns over time.

The border is an imaginary line.

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