First we have an Honorary Cat™ (also known as a fox) sent by reader Graham with the note:
As I’m typing this the fox is sitting in the garden, making itself at home and ignoring me. Photos taken with a Pentax K-500 with a Sigma 300 telephoto lens. Hope they’re good enough for your website :-).
And a wonderful series of photos of a rail attacking a crab on the Indian Ocean island of Aldabra (a coral atoll), sent by reader and biologist Dennis Hansen. Note the flightless rail, of which there are several species. All, I recall, inhabit oceanic islands, underscoring the biogeographical observation that virtually all small flightless birds are found on islands. Evolutionists have several explanations for this, but I don’t think we know the answer for sure. Can you think of some?
This bird appears to be classified as a subspecies of the white-throated rail (Dryolimnas cuvieri), and I’m surprised that, given its flightlessness, it hasn’t been classified as its own species. It appears to be the last flightless bird in the Indian Ocean.
We’ve had three previous submissions by Dennis, and you should go back and look at these if you haven’t. One is of the giant tortoises of Aldabra, and the other two on the fearsome coconut crab (here and here).
Dennis’s notes are indented:
I saw to my great consternation that you seem to be running out of wildlife photos to share with your readers. Here’s a sequence of photos I took during fieldwork on Aldabra Atoll last year. The flightless rail (Dryolimnas [cuvieri] aldabranus) is possibly the most feline bird I have ever seen hunting down prey. The elegance with which they dance and jump around is amazing. I am pretty damn happy they are only 20-25 cm tall, or I would fear for my own eyes, too.
#1: The flightless Aldabra rail routinely hunts down the large, terrestrial crab Cardisoma carnifex. The fearsome name of the crab suggests that it is a predator – but not here…
#2: First the rail hacks out the eyes of the crab with surgical precision… [JAC: This behavior is probably genetically encoded, but perhaps it is completely learned. I wonder if anyone’s studied that.]
#3 & #4: …disabled, unable to see, the crab tries to crawl away, but is attacked by the rail from all directions…
#5: …until finally the rail manages to turn over the crab; seconds later the crab’s struggle ends, as the rail’s beak stabs through its abdomen.
#6: This is the typical leftover after the rail has finished. Soon, other crabs will move in to scavenge the remains. Nothing is wasted on Aldabra.
A photo of the Aldabra atoll from Panoramio. Wouldn’t it be nice to work here? The atoll is about 34 km long.
and here’s a short video of the rail and its chicks:
I would have thought it was obvious that the reason why only islands have small flightless birds, is that only there are there no predators which will eat them. Rats and snakes for example, when introduced to such places have pretty much done for any small flightless birds that lived there. But if the scientists who specialise in this sort of thing can’t agree I guess it must be more complicated than that.
Clearly predators have a role, but is that the entire explanation? What is the selective advantage of losing flight, which, after all, still helps you get from place to place, find mates, and find food. The “no predator” explanation is based on a correlation, and seems likely to be right, but do we know for sure? We know that when predators are introduced to oceanic islands, the flightless birds get extirpated, but what is the selective advantage of losing your ability to fly? If there’s a convincing empirical demonstration, I don’t know of it.
Energy/development budget, I think. In a predator-free environment, individuals that spend less energy on flight will be able to invest more in offspring. I think that’s quite a strong selection pressure.
There are some cool ‘natural’ experiments where this could be studied. I’m thinking of some of the small New Zealand islands, where extinct flightless rails are being replaced by closely related, but not-yet-entirely-flightless ones.
& Thanks a lot for finding the photos worth sharing! I’ll send some more Aldabra visuals your way soon (it is indeed quite a place to work!).
I suppose that domestic chickens and turkeys might be an example. These two specie as well as the rail evolved naturally and artificially to a size that made flight very difficult. With no mammals and few other predictors as well as easily accessible food sources flight was a trait that was to costly to maintain. Use it or loose it.
I was actually just thinking that the phrase, “thin as a rail,” obviously doesn’t refer to the bird.
b&
According to many birding sources, it actually does. Scroll down to some of the shots of the Clapper Rail here:
http://woodswalksandwildlife.blogspot.com/2014/05/so-many-shore-sights.html
And this shot:
http://www.birdperch.com/images/Clapper_Rail-12.jpg
Woah — you embedded a picture! How’d you do that?
b&
Yeah, I’d like to know, too, although I foresee dire results if lots of people read the answer!
RE embedding the picture–it was a complete accident. I found the shot via Google Images and copied the url, expecting just a link to appear here. At least I think so–I was as surprised to see it show up as anyone else. 😀
Test:
http://www.lloydspitalnikphotos.com/d/6750-4/clapper_rail_F5R8317.jpg
Yep, that did it.
This happened here (WEIT) a few days ago, too, to someone else. Perhaps it’s a new feature for WP?
I could see it becoming tedious depending on the nature of the shots posted, but I’d like to see how it goes if our esteemed host permits the experiment. Images can add interest and even information to threads.
(I predict more accidental images are going to be embedded anyway.)
Did you paste the link or the image file?
One more test, to see if it works from my own photostream:
https://www.flickr.com/photos/82741306@N03/14029066395/
Weird. Must be a new WordPress thing. The only way around it would be to hand code the href.
Like this
Instead of this (pasted)
http://www.birdperch.com/images/Clapper_Rail-12.jpg
Voila! That’s a Virginia Rail, btw.
Diana, I just saw your question. I post the url from the tool bar, not the link one gets from the Flickr share function. Though let’s experiment with that method, too:
https://flic.kr/p/nnqykb
OK, for Flickr either way works. The Flickr share link is just abbreviated.
Perhaps you can do the image file experiment–I’m not sure exactly what you’re referring to there… :red face:
Well, let me try another experiment:
http://trumpetpower.com/images/trumpetpower.com/photos/Baihu_on_set.jpg
That was a copy-and-paste of this link:
http://trumpetpower.com/images/trumpetpower.com/photos/Baihu_on_set.jpg
b&
Fine figure of a feline:-)
Yes, he is! And thanks!
b&
Is he currently basking in his glory?
Right this moment, he’s fast asleep between the blinds and the glass in the living room window, contorted into some bizarre shape that only a cat could find relaxing….
b&
I.e. Basking in his glory🐱
He don’t need to bask in glory; he is glory!
b&
Glory, glory, Baihuaaaaaah
Teacher bit me with a toooooooth….
b&
Bit me with a tooth???
I thought it was hit me with a rooooler
What is cool, is it also appears in the email.
That was how I first noticed it — and a good thing, too.
“Those who remain ignorant of USENET are doomed to reinvent it…poorly….”
b&
Hey — it worked! Woohoo! Looks like we can paste URLs to arbitrary photos and they’ll embed.
…I feel another Da Rool coming on, though — best not to abuse this, I’m sure!
b&
I so had ideas after reading this post and it was so hard to hold back.
Diana, I see we’re cross posting. 😉
Experiment to see if dropping the http:// part works to prevent embedding:
flic.kr/p/oLzPcS
Yep, except that WP doesn’t put back that part like it does for, say, YouTube vids, so you don’t end up with a hotlink, which I personally find annoying.
No idea what you mean by hand-coding the href.
Hand coding the href is using HTML to create the link – replace the { with < in my example:
{a href="URL"}text for URL{/a}
Or to be more accurate, I should say replace {} with
Damn, word press ate my brackets. Try again replace {} with
LOL you win WordPress.
Ha, ha!
I got what you meant the first time. Knew I could count on you–thanks.
I’m doomed. I feel a new Rool coming on: NO SUPERFLUOUS POSTING OF PICTURES!
LOL! This is what prevented me from linking to some random picture. I knew it would be me to get in trouble because I’d be the last guy to do it so I didn’t. Phew!
Kindly define superfluous- lol
Aw, sweet Baihu shot–and interesting composition. 🙂
Thanks!
That’s actually a full-frame shot right out of the camera. I had the studio set up for something else, had likely just moved something off in preparation to put something else in its place…and he plopped down right where you see him.
(It’s a seamless white backdrop he’s sitting on. And I very likely edited out background shadows from imperfect lighting, maybe an intruding light stand, that sort of thing.)
b&
Ah, so Baihu’s a visual artist as well. 🙂
Had you wanted to stage that, I’ll bet he’d never have cooperated.
You might be surprised…I was able to get him to suitably inspect a number of my Dad’s works of art when I was photographing them to be able to include him in several of the final shots. He makes for a wonderful scale reference….
b&
Oh, I remember you posted one of those shots here and it was striking!
On reflection it is easier to get a nice shot of a cat; point a camera at a d*g and in a second all you’ve got is a nose-print on your lens.
-)
“I’ll send some more Aldabra visuals your way soon…”
I misread not surprisingly the word ‘visuals’ as ‘victuals’. Excellent photo series!
I was thinking the energy budget angle as well. Flightlessnes for birds on islands would have similarities to eyelessnes in cave animals, limblessnes in burrowing animals, and so on.
It could start with selection for the smaller, weaker (and cheaper) organs, then selection to start really shrinking them down since they are only a liability at that point.
Did you see PZ Myer’s post on the results of research with the Mexican blind cavefish? Turns out in this case, it’s “Because hedgehog and pax6 are negatively coupled to one another, one can be expanded only at the expense of the other, and what is going on in the blind cavefish is not selection for an economical reduction of the eyes, nor the accidental loss of an organ that has no effect: it is positive selection for a feature that is only indirectly related to the eyes.”
I’m going with the splint on my finger as the excuse for that html tpyo.
Indeed, having a “Just So” story that satisfies myself is not science. I think the energetic cost of flying along with the restrictions it imposes on body size (though this one is less relevant to small flightless birds) and other morphology is likely why giving up flight is worthwhile for some. The cost benefit outcome of all these presumably dictates which birds continue to fly, most of them, and which abandon it. I wish I could do the research necessary to look into it, but a nutritionist is not likely to be looked on kindly in an application of this sort, even after I finish my thesis. :-/
Isn’t there also a hypothesis about the dangers of being blown away from your island if you fly? Sounds rather silly simplified like that, but I seem to remember something about it seeming adaptive to stay put if you find yourself on an island in the middle of an ocean…
Yes, that is one hypothesis, but I’ve always found it dubious, and I don’t think there’s any evidence for it. Another is that by eliminating the expensive physiological and morphological apparatus for flying, or reducing the energy for that (and you don’t need to fly, supposedly), you can divert your resources for reproduction.
The problem is that there are plenty of theories but, as far as I know, there have been no tests.
I expect that most arguments include the aspect of scarce foodsources on islands, so any energy expended in flight, or growing wings to start with, is gonna cost you.
But per Ms. Elk, here is my hypothesis, which is mine. Fierce winds whip across islands routinely. Any bird extending its wings even a bit is likely to get blown away, so smaller wings rapidly offer an advantage, and no wings really give an aerodynamic advantage.
I like this hypothesis, since it brings in weather data (from monitoring stations and historical accounts) that could be used even on islands with extinct flightless birds.
I’ve always thought that the “no predators” explanation might be on the right track but it’s too simplistic. Resident (nonmigratory) birds don’t just fly to escape danger. Flying is an efficient way to find nesting, roosting, and feeding sites, and to locate mates and claim territory. All of those things require less flight on a small island, so running or swimming might be more efficient for heavy-bodied birds.
I enjoyed the photos. You can’t go wrong with the crab/bird/beach/forest combination!
I should have read further before I posted a comment above.
I’m sure I remember this as at least one hypothesis put forward by biologists.
Cool bit about the crab getting its eyes out.
I wonder if it will ever be to human’s advantage to have more information that is useful to us become genetically encoded. Like having some built in basic logic, or some math concepts, or basic Newtonian physics.
Sure. At one time, knowing how to program a VCR would have been useful to know intrinsically, but now it would be useless.
Even better, the clock on the VCR…
One bit of useful genetic information probably takes, at a low minimum, one death. Most human deaths are obviously senseless and useless, so I don’t think we’re building new instincts at anything like the maximum possible rate. One the other hand, we’ve built up capital: if population ever comes down to sustainable levels, our beneficiaries may have internalised General Relativity, not just Newtonian mechanics.
[One] -> On
What makes you think those things aren’t already genetically encoded? The rules of logic and arithmetic weren’t invented out of whole cloth; they’re formalizations of our native intuitions. The ability to express conditionals and counterfactuals is universal to human language.
Our intuitive physics is not strictly Newtonian, but is good enough to enable us to catch fly balls, or bring down birds in flight.
If you’re talking about information of an explicitly scientific or technological nature becoming fixed in our genes, that would require our technological and cultural environment to remain stable for tens of thousands of years at minimum, which seems unlikely.
On the other hand, if our descendants establish permanent populations elsewhere in the solar system (e.g. Mars, the moons of Jupiter and Saturn, the Kuiper Belt) then I’d expect them to eventually develop instincts suitable for survival in those environments. Whether you’d still want to call them human is a different question.
As you note, that hypothetical is unlikely, to put it mildly. But, should it happen, I’d be as happy calling them human as I am calling us apes, primates, mammals, tetrapods, etc.
b&
Poor crab! I like the shot with the rail behind.
The fox is so sweet! I love foxes!
I am going to go there one day.
The Aldabra atoll goes on my list.
I’m going to go look at a sailboat today. I’m hoping it’s going to make my first sentence a reality.
As I said in my comment on the Caturday article, it’s awesome to be alive right now. We are very lucky. We can travel the world, or stay at home, in our heated living rooms and see it from there.
For interest, just in case anyone is tempted to think of flightless rails as just a weird, peripheral curiosity of the bird world, this 1995 paper by David Steadman suggests that in the very recent past, they may have accounted for something like 20% of all living bird species. Subfossil remains of one or more endemic flightless rail species have been found on almost every Pacific island that’s been investigated by archaeologists, and a bit of back-of-the-envelope extrapolation suggests they may have added up to around 2000 species. They’re virtually all gone now, sadly – the Polynesian colonists and their rats did for most of them, with European colonists dealing the coup-de-grace in the last few centuries.
http://web2.uwindsor.ca/courses/biology/weis/55-437/Steadman.pdf
Simultaneously fascinating and depressing as hell. Considering that prehistoric humans are also suspected of having wiped out the megafauna in the New World, it’s shocking to think of how much damage our species had done even before the modern age…
Aren’t we just another example of natural selection by predator?
Sub
The flightless kiwi has the largest egg in comparison to body size of any bird in the world.
In New Zealand because of it’s isolation many birds opted for the flightless life. There was only one mammal and that was a bat, which from memory was not a great at flight either and spent a lot of it’s feeding time on the ground foraging for insects.
The biggest was the Moa weighing in at 250 lbs for the female and about 9 different species.
These flightless took up the niches that would have been filled by mammals
“[JAC: This behavior is probably genetically encoded, but perhaps it is completely learned. I wonder if anyone’s studied that.]”
In the words of Pauli, this is not even wrong. From an evolutionarily-informed cognitive science perspective, neither genetic encoding or learning are coherent, let alone plausible, explanations of behavior. If behavior is most proximately caused by brain mechanisms (i.e., representations and algorithms instantiated in brain tissue) interacting with the environment, and if the brain mechanisms are the product of gene expression (*causal* gene-environment interactions, not to be confused with statistical G-E interactions), and (finally!) if the causal G-E interactions, assuming they are non-random and suffciently complex, are orchestrated by natural selection, then it makes no sense to talk about behavior as being genetically encoded or learned. It’s not just that it’s too simple a way to cut things up; it’s that it’s incorrect and misunderstands the proximate and distal causes of behavior.
What also worries me is that speaking of the causes of behavior in this way moves the discussion backwards because it poses the problem in the language of behaviorism (most behavior is learned) or sociobiology (most behavior is genetically encoded). But both were shown to be inadequate for explaining behavior b/c they didn’t appreciate a) the importance of the nervous system in processing information in order to regulate behavior and b) that natural selection acts on the nervous system, not behavior. Both have been supplanted by an evolutionarily-informed cognitive science (including cognitive neuroscience). For people interested in a modern take on how evolutionary theory and cognitive science actually come together, there are many good sources including Pinker (Jerry, I know you read him, which makes these comments all the more surprising), Tooby & Cosmides, Buss, Bloom, Gallistel, Kurzban, Barrett, and others.
I don’t need this lecture, nor your snark. “Not even wrong,” really? It’s clear what I meant here: if the behavior itself is completely learned, it will never appear in any environment where the bird hasn’t observed it. If it’s purely genetic, it will appear in all environments that have crabs. Is chess playing in our genes. It’s possible because of our genetic endowment, but nobody would say that natural selection has favored genes for our ability to play chess. It’s clear what I’m saying here: are there genes that were selected to give rails a propensity for eye plucking.
Your pedantry is unappreciated. Yes, we all understand how genes interact with environments, but my question in this post was pretty clear.
My earlier post was incomplete and inadvertently posted (from a so called smart phone) ‘sorry about that chief’ here’s what I tried to say,
New Zealand was a hot house for flightless birds and of interest to me. Yes I’m a kiwi. Hence,I would like to make this personal observation about flightless birds.
From what is known about this phenomenon of how dinosaurs took to flight, the fossils from China of late are promising in that direction. But more specifically the selection pressures, the evolutionary changes over time that produced this mode of mobility, it seems not to much of a stretch to me that a partial or full reversal would not be out of place for what was once a terrestrial dwelling animal, to find it’s feet again.
Providing the selection pressures allowed for this to happen, which seems to be the case in New Zealand.
For a more articulate explanation of why this is I recommend this book, if I am allowed,
Ghosts of Gondwana. The history of life in New Zealand by George Gibbs.