I have a similar story. I was taxiing a Cessna 152 at LHBS. It is a big grassy field. On that day there were a large flock of black birds sitting on the grass. I made the usual radio call to announce that I'm leaving the runway and taxiing to the tie-downs when the birds flitted away just between my airplane's nose and my destination. The birds outside of that "road" by roughly a wingspan distance remained on the ground and kept doing whatever they were doing. And the ones who took to the air settled back a short distance away from my future path.
Now just to clarify I don't think the birds were listening on my radio call. The way I explained it to myself is that they were observing airplanes coming and going long enough that they learned that if an airplane hesitates at that point the next thing they will do is to turn towards the tie-down area. Or maybe it was just randomness. Or maybe as I was making the radio call I already started turning and they just got scarred away by my engine noise.
I see pigeons and sparrows dodge cars by inches, too. For that matter I do the same myself! Sparrows hawk insects out of the air, and I believe starlings also. Predicting motion would need to be second nature, I think. Like skillfully catching a ball, but much more so and between your teeth...
Correct. They would be visibly laminated to the pavement or smashed in the gutter. It does happen, but less often than ospreys drop fish in late summer.
But it makes you wonder why they cut it that close. What benefit they get from it. I can think of several plausible reasons but none that is self-evidently true.
Why waste energy giving someone else a free shot at whatever you're finding it worth your time to stand in the street over? It isn't that someone else wants that dropped french fry or whatever. It's that everyone else does.
This is quite common prey animal behavior. Larger predators have a harder time adapting to rapid turns made just as the jaws/claws are about to snap shut.
When I was in college, I once walked down a sidewalk that had been taken over by geese. Twenty or thirty big geese, sat down on the ground, who didn't even bother to get up on their feet I as I passed by. I wondered how they knew I wouldn't kick them, as I easly could have, and I concluded they had figured out that polite humans would just walk around them. Which I did.
I've seen the similar behavior from the ducks and geese in my neighborhood. Not as extreme, but sometimes I'm out for a walk, and they'll keep a wary eye on me, but will be content with the situation at 6-10 feet away, and won't actually take off unless I try to chase them. I don't think it's so much that they're "cutting it close" as that they're justifiably confident that humans are too slow to catch them at that distance and generally don't even try. But on the other hand, different groups of them seem to have different distances they're comfortable with. It's not like they've all solved the same optimization problem to three decimal places - some are confident and some are wary.
Of course, there are lots of stories of animals who got overly familiar with humans right up until the humans surprised them. As a funny example, I remember one time a cat that had grown up around my not-very-athletic family escaped the house and had to be brought back inside. At one point, it made a break for it along the long side of the house and was visibly shocked when my runner of a fiance ran it down and cut it off. This wasn't its first time running from us, but it had never run from him before, and it clearly didn't think humans could be that fast.
I don't think animals optimize as hard for benefit in everything as biology might lead you to believe. They build experience. They make mistakes. They're very cautious in new situations, but they can also be confident to the point of cocky if they think they know what you can't do. There's lots and lots of videos of cocky animals guessing wrong. It makes sense to me that maybe every individual animal isn't prudently optimizing hard for its own survival so much as that the group of them, with different temperaments, try different things and sometimes it works out and sometimes it doesn't and maybe there's a balance between weeding out dumb ideas and retaining the capacity to try things.
I think the idea that animals are always optimizing for survival and that everything must be for some benefit is misleading anyway. I mean, in an ultimate sense, you could say the same thing about humans, that they must always be optimizing for survival and reproduction, and whether or not that's true, it's definitely not true in a simple and obvious way on the level of day-to-day activities. We do a lot of dangerous and dumb and non-productive stuff. I don't think animals are different.
In fact, it makes sense to me to leave some reserve capacity. If surviving in good times takes all your time and energy, what are you going to do in hard times? Therefore animals typically have a lot of time for goofing off, and that certainly seems to me like what they're doing most of the time. They would similarly have room for trying stupid things and taking unnecessary risks.
> "it made a break for it along the long side of the house and was visibly shocked when my runner of a fiance ran it down and cut it off"
I still remember the look on her face when I got to the corner before her. She looked at me like "what is this terrifying new creature?" as she stumbled backwards looking for a way to escape something faster than her. By the time she'd decided on a course of action, someone else (I think your brother) had grabbed her from behind.
At the main bus port of my city, you can see heaps and heaps of pigeons casually strolling right in front and even below the buses while they are still driving. There definitely has to be learned behavior for the pigeons to be so completely devoid of fear in that situation.
No. Flicker fusion only happens when the same image is shown at the same position.
Something like a moving mouse cursor shows the same image at different positions. As an experiment, create a fullscreen image with the opposite color of your mouse cursor. Look at a fixed spot of this image, then rapidly move your mouse cursor across it. Rather than a moving image, you will see a bunch of copies of the cursor at fixed positions.
Similarly, track a rapidly moving cursor with your eyes. It will appear blurry, even though your eyes have no trouble sharply seeing an object moving at that speed in the natural world.
You can also try flashing an image for a very short amount of time. You'll be able to see and remember its content, even when it is being displayed for a period far shorter than flicker fusion would suggest you'd be able to see.
Just do a basic double blind test. get someone else to switch the hz a couple of times for you, and see if you can tell the difference. i would be surprised if you got anything less than a 100% success rate.
Our flicker fusion rate is different for the fovea and nearby central vision vs the peripheral vision.
The central vision is slower-response, higher-resolution, and of course color vision.
The peripheral vision is monochrome and has a much faster flicker-fusion, tuned to picking up motion in the periphery.
So, the same flicker rate that you never notice on a small monitor may flicker annoyingly on a large monitor. To check that a setup will not flicker for you, set it up in a darkish room, focus around 70°-100° to one side of the monitor so it is in your peripheral vision, and both look at one place and notice your periphery, and also move your focus quickly from one place to another and notice if the screen blurs like bright stationary objects or looks like a discontinuous blur (really easy to get that effect with fluorescent lights). Do it both left & right and towards the ceiling. If flicker shows up in these tests, it will still eventually bug you when looking directly at the screen, even if it isn't as noticeable because your focus is in the center of your vision.
That talks about the mechanics of visual perception. I'm discussing qualia, which I am far more confident crows share with me than does the particular subtype of Hacker News commenter who will with tiresome predictability and total lack of novelty turn up to press the footless insistence that crows could never.
I'm not an ornithologist but I think birds integrate some onboard magnetic compass sensors. So, it would be interesting if they can pick up the magnetic part of an electromagnetic wave of the radio. Seems very low likelihood but would be cool.
"Picking up" and "discerning useful data" are very different.
I'm not even talking about "deciphering". Even knowing that energy in a certain bandwidth means planes about to leave seems a large jump - and a radio tuned to a station is likely an order of magnitude more stringent than an animal's sensory abilities.
That's close enough to the cutoff that I could see it being in range maybe for the right species or even a slight mutation/evolution. Even if all they know is "I know North but a little less definitively than usual", that could be enough.
I read somewhere that migrating birds often use human infrastructure - roads, railways, power lines, etc - as landmarks or even "route markers" for their migrations.
A bit of a shower thought, but I think you can probably generalize that idea: Most birds spend a significant part of their life in the air, looking down onto human-designed landscapes. The aerial view of our cities is probably as familiar to them as our neighborhood streets are to us.
But unlike Google Maps, they see the city moving - all the cars, pedestrians, trams, railways, etc. It seems likely to me that if this is what you see day-in, day-out, because it is literally the space you are living in, you will pick up some general patterns in what you see and might even start to experiment how those patterns can be exploited.
> Most birds spend a significant part of their life in the air, looking down onto human-designed landscapes. The aerial view of our cities is probably as familiar to them as our neighborhood streets are to us.
The opening few chapters of Perdido Street Station does a great job of conveying this difference.
> Cooper’s hawk is on a rather short list of bird of prey species that have successfully adapted to life in cities. A city is a difficult and very dangerous habitat for any bird, but particularly for a large raptor specializing in live prey: you have to avoid windows, cars, utility wires, and countless other dangers while catching something to eat every day.
Peregrine falcons adapted quite well, and they're much more sizeable. That said, their size make them very apt to hunt pigeons, so this could be a less risky niche to hunt for; I mean, pigeons usually fly higher up than sparrows.
The Black Redstart evolved to live in holes in cliffs and the like, and never used to be widespread in the UK. After the second world war, cities all over the south were bombed out, and they moved into the deserted, derelict bombed areas in great numbers. As the bomb sites were cleared and the cities redeveloped, their habitat was eroded. But at the same time, Britain was de-industrialising, and they moved into the abandoned factories in the North. As those now get redeveloped, they are losing their habitat again.
Even his death (due to a collision with a building) was likely less because of his ability to survive, since he managed to learn all the skills necessary, and more due to the fact that his primary food source, rats in and around the city, were laden with rat poison.
We have consistently and regularly underestimated non human animals cognitive abilities which is frankly strange if you understand evolution since it would be strange for only humans to have a certain evolutionary feature such as intelligence and every other species to not have it at all.
> underestimated non human animals cognitive abilities
I think humans have done precisely what humans do: misunderstand. Unlike other animals, humans don't have the ability to understand creatures they have not studied for long periods of time.
We know animals are intelligent. But we don't know what intelligence means. Is it something we can use? no? then it is something we ignore. And it is most likely something we disrespect.
There are Peregrine falcons in my city. I remember walking downtown one time and seeing one on the sidewalk with a pigeon in its talons. All the commuters and I just walked around it. Really weird somehow.
London apparently has a high density of them (but high density still only means something like 40 breeding pairs), and some people are all excited about the prospect that they can do something about the rapidly rising wild parakeet population...
I'm having a hard time squaring away the image of grey gloomy London also being overrun with colourful tropical looking birds, I had to google it and see.
They’re surprisingly well adapted to a large range of temperatures because of the species found in temperate rainforests at higher altitudes. They frequently enough escape from pet stores and zoos that there are many sizable populations spread out around the world. The one nearest me is the infamous Pasadena parrots [1] which is made up of thousands of birds likely built up over decades of escapes. There are populations in Chicago, New York, Rome, Tokyo, and plenty of other cities in the world.
> Peregrine falcons adapted quite well, and they're much more sizeable.
I'm not sure what you mean. As far as I am aware -- and according to every source I've looked at in the last few minutes -- Peregrine falcons and Cooper's hawks are about the same size (length and wingspan are within 1-2 inches).
Peregrines are somewhat smaller and much more lightly built. I live in a nesting pair's territory which often sees transitory Cooper's; they're easy to distinguish both in flight and at rest. Male Cooper's are more peregrine-sized and hard to tell from sharp-shinned hawks sometimes, but that is an ordinary enough sexual dimorphism in birds.
Interestingly, while peregrines and accipiters like Cooper's share a habit of taking passerines in flight, the response of potential prey seems to differ. I frequently see songbirds mob a Cooper's; I can't think offhand of a time I've seen them respond to a peregrine other than by crypsis.
Sadly we don't have Cooper's around here so I have no experience with them, hence why I looked them up (see nearby comment) and according to that source found out they were on the smaller size and much smaller weight.
Around here the only ones who would dare mob a peregrine would be crows.
Sure. I'm just talking about the impression they give in life. But I suppose in that sense the other birds must find a peregrine much more striking, and it very belatedly occurs to me that peregrines no doubt look smaller and more gracile to me for the higher altitudes their stooping hunting habit would require. When I do occasionally see them on approach to their nearby nest, I'm struck by their relative size. So yeah, between that and reviewing my Sibley's the error here is mine, though - for that matter, likely also because - I do find all falcons rather streamlined and compact in impression compared with accipiters or buteos.
> Total length of full-grown birds can vary from 35 to 46 cm (14 to 18 in) in males and 42 to 50 cm (17 to 20 in) in females. Wingspan may range from 62 to 99 cm (24 to 39 in), with an average of around 84 cm (33 in)
> In northern Florida, males averaged 288 g (10.2 oz) and females averaged 523 g (1.153 lb). In general, males may weigh anywhere from 215 to 390 g (7.6 to 13.8 oz) and females anywhere from 305.8 to 701 g (0.674 to 1.545 lb), the lightest hawks generally being juveniles recorded from the Goshutes of Nevada, the heaviest known being adults from Wisconsin
(not putting the full regional rundown, just the biggest entry)
In my neighborhood in the East Valley in Phoenix, I’ve seen Cooper’s hawks, kestrels, peregrine falcons, zone tailed hawks, merlins, and one immature bald eagle. Along with the numerous turkey vultures and the occasional black vulture.
Plus pigeons are not exactly known for being incredibly smart or agile, so if you're big enough to take one down, you probably won't struggle too much for food.
Pigeons are actually known for being very agile, and are able to do vertical takeoffs and evasive maneuvers like a backflip loop immediately after takeoff, which is precisely to evade predators like falcons.
City pigeons just tend to become fat, lazy and used to suppressing their flee response around traffic and people.
Pigeons fly surprisingly fast and can outfly smaller raptors in a straight line. A stooping (diving) Peregrine will usually win. Its strike may decapitate the pigeon which tends to minimise the struggling
Except that it's not clear whether the intelligence† that underlies their homing ability is equally effective in helping them evade predators.
†Is "intelligence" even the right word here? I don't know. Much depends on how you define it, I guess, combined with the unknowability of the pigeon's own mental processes.
I once wrote a personal’s ad in SQL on Craigslist, back when they had that section. A DBA replied and asked if I wanted hawking. She had a Cooper’s hawk. I met her at a commercial park in a Saturday morning. She was driving a Honda CRV, the hawk was in the front passenger seat, and I hopped into the back seat.
She started driving and spotted some crows. The hawk saw them as well. Wearing a “don’t kill me either your claws” glove, she moved her hand to the hawk, who gleefully jumped on. She rolled down her window, stuck the hawk outside, and it was basically a drive by shooting with a bird bullet. This happened three times.
My most vivid memory of this was her ripping the crows apart into pieces and putting the then into a bucket, like it was sushi you’d order from KFC.
This is one of those stories that just keeps escalating into "am I in a dream or a side quest?" territory... Also, "sushi you’d order from KFC" is going to haunt me
They have a much stronger sense of propriety than most humans. So really do most animals other than us and perhaps some close relatives. I'm not actually sure that says anything in our favor.
Wow... It's not just that the hawk figured out a clever hunting tactic, it's how it did it: linking an auditory cue (the pedestrian signal) with a future visual scenario (a longer car line) and then using that cover to hunt. That's a level of abstraction and planning you don't usually associate with birds
You do associate those traits with birds in the raven family.
I figure the usual association with birds or perhaps animals in general is still mostly based on ‘humans smart; animals dumb’ instead of actual research.
I was about to call fake on this -- Americans from south Jersey are largely unfamiliar with the present perfect and would not say "[I] have never heard of" but "[I] never heard of" instead.
But it turns out this grammatical cue is an effective way to discover that the comment is not about an American south Jersey but a British one.
What a clever Cooper's hawk! It is adapting to urban life and has learned to make use of the available conditions to make it easier to find food. Doesn’t this also prove that the environment can change both humans and animals? "Survival of the fittest" is probably what this means.
I've watched karasu carefully wait for a yellow light to drop his walnut in an intersection. The last car passing cracked his nut, then he had time to gather the meat during the light change before other cars came along.
Some crows in Japan do something like that, dropping nuts on/near a pedestrian crossing, and waiting for a green pedestrian light. See https://youtu.be/BGPGknpq3e0?feature=shared
Japanese crow-dactles would put candy in wrappers into crosswalks and let cars run over them. They may have used the sounds of the crosswalk. I have no sources, just anecdotal.
They were big birds. Intimidating wingspans, if hit by cars on their highways: they damaged cars, etc.
I once saw racoon prints descend from the rafters in a barn, complete with little muddy handprints on the doorknob into the feedroom, like some sorta sylvan-bandit tom cruise.
When food is on the line, animals can figure all sorts of things out.
Of course, I prefer the double-c variant because of the orthographic anomaly of the person who tends to the raccoons' area at the zoo, the raccoon-nook-keeper.
The point the story tries to make is that the Hawk learned traffic signals. That is not necessarily the case. It could be that the hawk just sees that the cars are blocking the sight of the prey.
Still an intelligent action, only does not mean the hawk understands the signal itself.
The suggestion is that the hawk hears the signal and knows that the line of cars is about to be unusually long in a minute, so it prepares by flying into position.
the story as told outlines that the hawk will stage itself when it hears the sound of the crosswalk, in anticipation of the line of traffic getting long enough for it to use as concealment.
Now just to clarify I don't think the birds were listening on my radio call. The way I explained it to myself is that they were observing airplanes coming and going long enough that they learned that if an airplane hesitates at that point the next thing they will do is to turn towards the tie-down area. Or maybe it was just randomness. Or maybe as I was making the radio call I already started turning and they just got scarred away by my engine noise.
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