Two can play that game

While I had been planning to put this post up soon, Dr. Jerry Coyne over at Why Evolution Is True beat me to it with his own post about snakes, but his includes some great video, including a stunning sequence of an egg-eating snake! I hate it when someone on my blogroll to the right upstages me, even before I actually post! Although he’s a university professor and author, so I suppose that has privileges…

For some unknown reason, I have seen surprisingly few snakes this year, which is annoying to someone that likes snakes as much as I do. My property, which plays host to as many different animals as it does (including some resident treefrogs in a potted plant,) does not seem to cater to snakes. Now just a few days ago, as we get late into the season and the days are starting to get chilly, I glanced down at the base of a tree at The Girlfriend’s house and spotted a short length of bicycle chain, or at least that was the immediate impression, soon replaced with one of recognition at the pattern of a young black rat snake.

Black rat snakes (Elaphe obsoleta obsoleta,) despite their scientific name, are very common throughout the eastern United States, and one of the largest you’re likely to encounter, at times reaching over two meters (six feet.) They’re great tree climbers, great everything climbers, and can even be found nesting in attics. As adults, they resemble little more than black garden hoses, having the same diameter and often seen “discarded” casually in the grass. Their white undersides aren’t usually apparent unless you pick them up, which is easier to do than you might imagine, since they are typically fairly docile.

The pattern of the young differentiates greatly. Their patchwork pattern of black spots on a medium-pale grey base makes many people think they are entirely unrelated, not helped by the size they are for their early years. This pattern helps them remain camouflaged while they are at this vulnerable size, since it blends very well against tree bark and in shady patches. And like many snakes, they usually become motionless when danger threatens, opting to avoid attracting attention rather than bolting for cover, which is what allowed me to capture this one.

Their diet consists of just about everything, including the namesake rats. But they also eat birds, eggs, and even other snakes if the pickings are slim. They’re constrictors, with a completely harmless bite, and their tiny teeth are good only for holding prey. Even if you manage to get one to bite you, you’ll display little more than tiny pinpricks of blood, not an honorable wound at all for intrepid Crocodile Hunters. I have used perfectly wild Black Rat Snakes for educational talks, because they are so easy to handle, but do not recommend retaining any wild animal as a pet. Not simply because they don’t belong and have drives to be outdoors rather than a small cage, but also because of the damage that can be done to them by poor diet and improper housing.

In the right conditions, the adults can be seen to retain vestiges of the patterns they had as young-uns, between their scales, but you typically have to look hard to see this at all. This example, of one roughly 1.5 meters (5 ft,) shows the pattern in bright sunlight, right there in the middle, as it heads straight up a tree. You might think they do this slowly, but you’d be amazed – they can scale a vertical rough surface at the same speed as their casual gate gait [cripes] on the ground (I suppose it’s improper to use “gategait” on something with no legs, but you know what I mean.)

In spring and fall, they can be seen in early mornings on the roads, or occasionally sidewalks. As “cold-blooded” (ectothermic) animals, they get heat from their environment, but when the nights are cold this makes them a bit sluggish. Since they often hunt at night, this can pose a problem to digestion, so they drape their wonderfully solar-absorbent bodies in areas to capture the maximum amount of warmth when the sun rises – unfortunately, this leads to many of the encounters they have with humans, in which they rarely come out unscathed. It’s a shame, since they’re simply doing their own thing and fitting in nice and snugly with the ecosystem.

I’ve encountered black rat snakes rather suddenly on a large number of occasions, sometimes in surprisingly close quarters. Doing animal rescue work years ago meant (as one of the people who had no qualms about snake handling) that I got many of the snake calls, and have removed them from attics, downspouts, front lawns, schools, and once the sidewalk in front of the public transit garage – where it had kept half the staff clustered inside against the glass door as it digested its bird meal. A few tried bluff displays, one actually struck – again, big deal. They honestly can’t do any damage. Mostly, they retreat, and in situations where they’re out in the open and suspect they’re in view, they can pull backwards with glacial slowness, hardly appearing to move at all, so as not to attract attention if they haven’t yet been noticed. Many species of animal, humans included, can miss the obvious simply because it’s not moving – I’ve spotted a black rat snake hanging out of a downspout on a porch, a few meters behind someone I was conversing with. They might have missed it entirely had I not pointed it out.

Like many snakes, they have a warning display when agitated, which is vibrating their tail madly – rattlesnakes only have a handy noisemaker, but they’re not the only ones to do this. When the tail encounters dry leaves the sound is fantastic, but even on a smooth surface the buzzing is neat. Coupled with a writhing coiled motion (see one of Dr. Coyne’s videos linked above,) it looks very ominous, but the threat from snakes in North America is way over-emphasized. Telling the venomous species apart is fairly easy – it simply means you have to look close at markings and memorize them. Even without this effort, leaving them be works fine; pushing them off with a broom, if they’re in a hazardous area, is usually sufficient. No snake can eat a human, so they only want to be left alone – you’re the threat, not them. The phobia many people have over snakes is a human failing, not the snakes’ fault, and no, it is not inherent or instinctual, it’s usually conditioned by culture. Get over it. Snakes are all around us, and by a large margin not even remotely dangerous. Get this: I actively hunt out snakes, know how to spot them and how to handle them, and still haven’t had an encounter with a venomous species in the wild, save for rescue calls (which were notoriously uneventful.)

Yes, I’ve heard the stories of people being pursued aggressively by venomous snakes, just like I’ve heard the stories of people curing their illnesses with crystals or homeopathic remedies. They’re the same level of total bullshit. The people who have to capture and handle these same venomous snakes as a matter of routine will tell you how unfounded the stories of aggression are. It’s all defense at provocation, nothing more.

My little buddy here, despite displaying a defensive coiled-and-ready-to-strike posture (when I did not have the camera handy,) never even attempted to strike, and was easy to handle. The pic below gives a fairly good indication of size. The Girlfriend, who really doesn’t like snakes, even thought it was cute.

This is not satire

That’s the frightening thing: it really isn’t satire, since it’s far too accurate. We’ve had a long run of stupendously ignorant politicians recently, and it’s really shameful.

I don’t do much about politics, because I really don’t have the patience for it. This is one of my vices; while I spend no small amount of time promoting critical thinking and the idea of not fooling yourself, I really can’t stand actually finding out how phenomenally stupid many people are, so I avoid the subject. But here’s a thought: maybe we can institute a simple law, where no one can hold public office until they can pass a standard high school GED test. Is that too much of a bare minimum competence standard? Hell, it should be much higher, but right now let’s set the bar realistically. I’d hate to see too many politicians out of work, because McDonalds only needs so many drive-through attendants…

Thanks to the Bad Astronomer for this video.

Things change

Just a few posts ago, I featured some yellowjackets working on their underground nest. Today, I discovered I was not the only one who had found them.

Sometime in the last few days, something had dug up the opening into the nest and removed several large portions of comb, leaving them strewn about the ground nearby. It was a bit curious, because the excavation wasn’t very deep at all, amounting to only about 20 centimeters (8 inches) at most, and maybe the same width – it didn’t seem enough to hold the number of combs I found. But the yellowjackets were undeterred, and were very busy on the exposed portions of the nest. Note, to the right mostly, the multi-colored swirls indicating the paper shells of the nest itself.

From the looks of the damage, this certainly wasn’t any human’s work, and I got no impression of a large animal because the area of disturbed soil wasn’t significant, so my guess is a raccoon or opossum. It just strikes me as odd that they would tackle this. Yellowjackets aren’t honey producers, and the larva are fed by pre-chewed insects that the adults capture. These combs, all apparently older and empty, are just like paper wasps’ nests, and house only the eggs and pupae. While this might be an enticing meal, it seems like a tough one to obtain.

Most of the hymenoptera have really lousy night vision, much worse than ours, and thereby very much worse than a raccoon’s or opossum’s. They usually do not fly at night at all, even when the nest is threatened. But they’re more than happy to swarm onto something if it comes within reach, which may be why the layers of nest visible in my shots remains undamaged: the old stuff near the surface wasn’t hard to tear out, but when the nighttime marauder got to the active nest a little deeper, it encountered the standing guard. The photos above were from daylight (though flash assisted) – the image below was taken at night, showing the sleeping positions of the yellowjackets.

Yep, stick your hand in there, see what happens. I’ve had my fill of things like that, and don’t care to star in any YouTube videos just for your amusement.

When I went out to seek this shot, I did so very quietly and with the assistance of a bright flashlight. Not to see the bees as much, but to try and catch the return of the marauder. I saw nothing, however, and the nonagitated state of the bees would seem to indicate that the night had been quiet. Perhaps the raccoon or opossum had learned its lesson. Or was returning with a bee smoker…

Can I make an amateur naturalist’s lesson out of this? Perhaps I can. If there are areas you frequent, it sometimes helps to look around carefully and pay attention to details, because then situations like this become obvious, and you have some clue as to what is happening when you’re not there. This can provide an opportunity to return and catch sight of the drama that often unfolds at night, but also to illustrate a story even if you don’t see what actually happened.

Get back to me with Phase Two

Like many pursuits and interests, critical thinking involves a subset of information, discussions, and approaches, many of which don’t capture the attention of those who aren’t interested in critical thinking. I’m well aware of this, so often you’ll see me break the blog posts up with the “Continue Reading” tag, so that no one is forced to read a topic that doesn’t motivate them. It’s kind of silly in this way, for two reasons: the first is, nothing I post is even remotely forcing anyone to read it, and something else is a mouse-click away. Secondly, I think critical-thinking skills are important for everybody, so I’m perhaps defeating myself by hiding things beneath the fold, as it were. Just think of it as my way of being… accommodating.

But if you don’t continue, you miss the cartoon video…

Can you see the light?

From time to time, I play around with infra-red photography, because it can produce some really cool effects, and also because there are ways to make it relatively easy. An old digital camera of mine, the Canon Pro90 IS, can not only capture infra-red light, it can focus it and calculate exposure reasonably as well. All that’s needed is an infra-red filter, such as the Lee 87P3, an inexpensive polyester sheet.

The reason this works is that most digital sensors can actually capture a certain range of infra-red (hereinafter “IR”) light normally, without any modifications. In fact, most quality digital cameras today include an internal filter specifically to block IR light because of this. I tumbled to it entirely by accident, when I noticed that foliage had a tendency to wash out in images made with this camera, as if the foliage alone was being overexposed. I already knew that foliage is one of the best reflectors of IR, so putting this together wasn’t a great leap.

But what is IR light anyway? Well, all light is simply energy in the electromagnetic spectrum, as is radio waves, microwaves, gamma rays, and cosmic rays. What we tend to call “light,” or sometimes “visible light,” is simply a particular range of wavelengths that our eyes are sensitive to, running roughly between 390 and 750 nanometers. Many light sources are not restricted to this range, however, and our sun is a good example. Wavelengths outside of this range are not detected by our eyes, but are still there – infra-red starts above 750 nanometers, and ultra-violet starts below 390 nanometers. Go even further, and it becomes one of those others that I mentioned above. Microwaves, such as those used for cellphone communications, are merely much shorter wavelengths of the same kind of energy.

IR photography simply involves blocking most of the wavelengths we consider visible, but letting through the near infra-red spectrum. Of course, you need a medium sensitive to IR light as well, which can be digital (and tends to produce more consistent results) or special films. But there’s a lot less IR energy than visible, in effect making the IR world more like twilight, so long exposures are needed to get a decent image, and the greater range of wavelengths blocked by your filter, the longer it needs to be.

Foliage is a remarkable reflector of IR light, so leaves in bright sunlight come up very bright. But the sky, nice and blue to our eyes, does not suffer from Rayleigh scatter in IR wavelengths, so clear skies turn up very dark, and get brighter with humidity because water does reflect IR. Thus the dark sky and white clouds. And because there is no Rayleigh scattering, indirect sunlight, clouds, and shadow all make IR light extremely dim, so the best results are obtained from brilliantly sunny and clear days (with maybe a few puffy clouds for sky accents.)

Other things reflect IR differently, so experimenting is best. Our skin, for instance, reflects a moderate amount of IR in comparison to foliage, so in a properly-exposed photograph, people look pretty normal, which can make a nice juxtaposition among the ghostly trees and dark sky – provided they hold absolutely still for the whole exposure time, which often goes into several seconds. Yes, a tripod is a must, and a remote release recommended.

Now, here comes more science trivia. Our sun puts out a wide range of energy in a curve, hitting a high peak at about 500 nanometers – yes, smack in the middle of what we call visible light. The thing is, we could see in lots of other conditions, and see entirely different things, if our eyes had a different or wider range of sensitivity to wavelengths. But they’d have to be more efficient, since our eyes now can detect only the wavelengths coming in with lots of energy – this is, of course, no coincidence, but a simple evolutionary advantage of utilizing the greatest available resource. Other species, however, can see different ranges, or with more sensitivity. Many fish can see in certain ranges of ultra-violet (UV) because it penetrates further into the water, and bees use it to spot healthy flowers, which produce a different reflection pattern in UV. Birds have a much more detailed range of color vision than we do, seeing more color overall – where we could tell no discernible difference between 500 and 500.5 nm, for instance, birds can. And they also have a range of UV they’re sensitive to, because it is reflected in plumage to varying degrees and can indicate the health and robustness of potential mates.

But why does it look black & white? Shouldn’t it look, well, red, or very red? With some filters, some color does indeed come through, but this tends to be visible light that is allowed to pass by the filter’s composition. You need to be aware that neither digital sensors, nor the light-reactive chemicals in film emulsion, react to color in any way – both only react to light intensity. To achieve color, you basically need to filter for that color, just like putting on colored sunglasses. For film, it’s different layers of emulsion set into a colored gelatin. For digital, it’s actually a micro-screen of colored filters over every pixel in the sensor. In other words, digital sensors have a dot pattern like a TV screen, but this is eliminated by algorithms in post-processing. IR light, however, corresponds to none of these digital filters, and trickles past all of them equally well in the examples above. Most likely, these colored filters block some of the IR light, which is part of the reason why exposure times can go so long.

Below, some examples of different IR filters on the same camera. At left, a filter allowing only wavelengths above 950nm, well past our ability to see. At center, one allowing wavelengths above 720nm, which intrudes into the visible spectrum and begins to get affected by the color filters in the camera. At right, a sneaky trick – using a black piece of developed slide film as a filter, in this case Provia 100F.

Wait, slide film? Yes indeed. The emulsions on many slide films block most visible light but let IR through, so a black piece of slide film can work. Because of the size of most lenses, you have to go with medium-format or large-format film. The Canon Pro90 IS has a 58mm lens filter size, so I was able to use the blank leader of 120 film which is 60mm wide, mounted in an old UV filter ring.

This leads to another fun trick. Light sensors in other areas are also sensitive to IR light. Slave strobes, for instance, are strobe units that respond to a sudden flash of light (or sometimes aiming them abruptly into bright sunlight, as I’ve blinded myself discovering.) So they fire off when they detect the camera’s strobe unit, and because light travels so fast and electronics introduce only tiny delays, the slave provides additional light to the image. They can be handy to have, since they can throw light from other directions without requiring any kind of wiring or radio linkage.

But let’s say, when shooting normal situations and not IR, you don’t want light coming from the camera, only from the slave set off to the side. Then you block the on-camera strobe with a piece of black slide film, which blocks the visible light but lets the IR trigger the slave. Cool, right? Just one of those quick and dirty tricks to make fancy lighting a little easier. Radio triggers are expensive.

Getting back to IR filters, you should note that all three images compared above have radically different exposure times. When shooting film, you’ll be advised by the manufacturer how sensitive the film is to certain filters (though you’re out of luck using slide film as a filter – the best I can say is that the Provia 100F used above probably lets an additional stop through over a 720nm filter.) With digital, the camera might set its own exposure correctly, or it might require some playing around.

Let’s not forget another tricky thing. Okay, we know that lenses bend light, and looking at illustrations of prisms, they can bend different wavelengths (colors) by differing amounts. Camera lenses are optimized to try and correct this rainbow effect – in visible light. But IR is outside of what they’re created to handle, so to even focus properly, you introduce some issues. Using film, for instance, you can’t focus with the IR filter in place, because we see only visible light, so you have to focus on the scene, then place the filter. But the lens is focused for visible light, and IR gets bent much further, so the lens is now out-of-focus for IR light. You need a lens with an IR mark (only some lenses include this anymore), and you adjust focus according to this mark.

See the red line by the “4” on this focusing ring? That’s the IR pointer. Once focused without the filter in place, you then shift the focus ring from its alignment with the center pointer (here, pointing at the back of the “5”) to line up instead with the IR pointer. You can’t trust autofocus in most cases because the IR filters don’t let through enough light for the sensor to get a decent contrast reading. The Pro90 can achieve autofocus, but it struggles with the 750nm filter, and is very balky with the 950nm filter – conditions have to be very bright and contrasty for it to lock on.

Want to know if your digital camera can produce IR images? There’s a simple trick, for those where the LCD can be used as a viewfinder. In relatively dim light, use the LCD viewfinder and have someone point a TV remote (any kind should do) at the lens and press any button. If you see a flicker of pale light from the front of the remote, you’re seeing the IR pulse they use, and your camera should be good to go – just find a filter!

Many Canon EOS film cameras are hampered in shooting IR film, because they use an IR light to count sprocket holes when advancing the film – this will fog the bottom edge of your images. It’s not a hard thing to shoot wider and simply crop this out, just be warned of the problem.

Unless you’re using film, you will almost certainly have some color cast to your images, even the ones that look B&W. You can simply eliminate this by converting to greyscale, or tweak this for good effect. You will probably also find that contrast is low, so boosting it afterward is recommended – play around with the levels until you achieve what you like best. The farm picture above has been converted to greyscale and adjusted in contrast to keep the midtones where I liked them. In the forest road photo at top, I left the color in and tweaked it, very slightly, towards cyan – it’s subtle, but it contrasts nicely with the page background color.

And you may have been waiting for me to explain the bright streaks, or figured it out on your own: yes, it’s a car going past during the four second exposure, with its headlights on. The car didn’t reflect enough light to do anything in the areas it traveled through, but the headlights were distinctly brighter, even in IR. I should have gone for eight seconds…

Two other examples of IR photos can be seen here and here. Finding the right conditions for a good image is trickier, but the results are worth it. Keep watching this space for more examples as I play around some more.

Do you want to know why?

In the same discussion I mentioned a few posts back, a particular quote from Christopher Hitchens came up, which was basically, “Religion poisons everything.” This kind of statement is fairly hard for many people to accept, and it is often treated as hyperbole, senseless exaggeration to make the case seem stronger. But I maintain that there is, instead, a veneer of respectability laid over religion, to the point that criticism of any aspect is often considered extreme, if not taboo. It is a veneer that is decidedly not warranted, and does in fact hide from us the damage that can be done. And is done. I present an example to you, one that is not unique in any way.

More from the neighbors

Early this evening, as I spoke on the telephone while standing on my upstairs patio, a “conversation” from the trees across the driveway drew my attention, and I cut the call short. While I couldn’t see anything, some very soft “wheet-a wheet-a” sounds were emanating from quite close by. Naturally, I grabbed the camera and started tracking the sounds, and eventually caught site of the birds seen above.

Common Flickers (Colaptes auratus) are found throughout North America, but tend to be shy, and being woodpeckers, prefer to stay within wooded areas. Their territorial call is a sudden sharp whistle, descending in tone, but what these two were using might best be described as the squeak of someone scrubbing glass, sharp but quiet initial note with a fainter followup, repeated regularly about twice a second and with varying pitch and volume. As they did this, they bobbed and twitched at one another. Since these were both males, as determined by the mustache mark alongside their beaks, I suspect this was a territorial discussion – another photo that I have, unfortunately not sharp enough to show anyone, shows raised feathers along the crest of the head, another dominance display. My best guess right now is that these are siblings from this year’s brood trying to decide who could lay claim to this part of the woods.

What allowed me to get these images was mostly my curiosity at the faint repeated “wheet-a“s, and remaining alert to any movement when searching the area. Their coloration, especially in partially shaded conditions, is very subtle, and you’ll most likely identify them by the flash of white at the base of their tail at the back (what birdwatchers call the “rump”) as they fly from one trunk to another. Shown here perched, they will just as often alight on the trunk itself and remain upright, which is of course their feeding/foraging position.

Another image that I caught shows off the lovely fawn coloration of their heads a bit more, as well as the red patch at the nape of the neck and the pointed tips of the tail feathers. Most woodpeckers use their tail as a brace and springboard for pecking, so the shafts of those feathers are likely quite strong. The breast feathers, with their spots, are very distinctive even when found by themselves on the floor of the forest. They’re fan-shaped for maximum coverage and heat retention, so rather than each spot belonging to only one feather, every feather has a collection of them – you’re seeing fewer feathers here than you might imagine.

I have a fruit-and-nut wreath birdfeeder to put up, but that’s hardly a natural setting for photos, so I might start getting creative by breaking it up and forcing the bits into crevices in prime photography areas. This will give woodpeckers and nuthatches something to do and allow me to use the best light and backgrounds, and still get natural-looking images.

One of these days I’ll get a decent sound recording system aimed for outdoor use and start podcasting the neighbors’ conversations. Donations, of course, are gratefully accepted… ;-)

Frustrations, part four

So this afternoon, noticing the massive activity at a yellowjacket’s burrow in my yard, I decided to try and get some nice close shots of their work. That would be called, “foreshadowing,” in English Lit classes, wouldn’t it? Ah, not in the way that you’re thinking…
Eastern Yellowjackets (Vespula maculifrons) are generally ground-nesting wasps, known to be the most aggressive in the area. Disturbing the nest, which is usually an unobtrusive hole in the ground, can cause them to swarm, and most especially so if you kill one of their number, which releases a scent that alerts the others. I have run afoul of this before, being stung over a dozen distinctive times in a frenetic couple of minutes. The advice is, “Don’t slap them,” but this is a bit hard to follow as they’re stinging you. Unlike honeybees, yellowjackets do not lose the embedded stinger on the first sting, but can nail you repeatedly. As I discovered then, spit on and clean off the spot where you smooshed one before it attracts more to the exact same spot. The stings can start itching madly at odd times for several days after the attack, by the way…

So what was I doing trying to get closeup photos of a nest that was seeing roughly 40 ingresses and egresses a minute? Well, not irritating them, for one. I used an extension tube on a 75-300mm lens to stay about a meter from the opening, and tried to time my shots for insects just leaving the ground. This is far harder than it sounds – yellowjackets appear at the mouth of the opening and are airborne in a flash, taking less than a tenth of a second to cut across the entire photo frame (which was far larger than shown in these tightly cropped images.) I’ve had plenty of practice, but I have an awful lot of empty frames.

When doing this, the air around was sometimes filled with their buzzing, and I had several land on me momentarily. I was sitting still, however, and made no aggressive moves, so as far as they were concerned I was nothing more than the branches near the nest that they occasionally lit upon. With lots of tries, and running the batteries almost dead in the strobe unit, I managed to get a few frames of merit, including the one below. Just before takeoff, a worker appears in the mouth of the opening with a dirt clod to carry away, clearly busy expanding the underground warren. This explained at least some of the frenzied activity I was seeing, and the dropping temperatures may be contributing, since they do not handle freezing conditions well and were likely trying to dig deeper before these occurred, where the earth would retain more heat as the surface cooled.

Should I have really wanted lots of detail shots of an insect in flight, this is the wrong way to go about it – the depth-of-field is way too short and the area for the wasps to be in too large. To control this, some insect photographers set up a rig where two infrared or laser beams cross at a particular point. These beams are linked to light sensors and into a device to trip the camera shutter – both beams have to be broken to fire the camera, so the insect has to be in a precise location. Since this is still unimaginably hard to achieve in three-dimensional space, another factor is occasionally added: a tube that empties out right near the crossed beams, just outside of the camera’s view. Insects are introduced into this tube and gently blown along it to exit by the crossed beams, so that they stand a much greater chance of passing through the key focus point. This is how the studies of insects in flight are often done. When time is money, you do whatever you can to increase the odds. As I’ve shown at top, you can indeed catch insects in flight without special rigs, but you’ll notice the shadow behind the wasp – it was barely airborne at this point, and I shot 86 frames trying for this, with only a handful of sharp images.

Disrespect my authoritah!

In a discussion on religion a short while back, I got to hear one of the more amusing arguments that has been forwarded frequently, apparently (somehow) in favor of religion: that atheism is simply a rebellion against authority. This argument has so many levels to it that I figured it deserved its own post.

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