Saturday, September 5, 2015

With A Name Like Ludlow Griscom You Have To Be Good

      Ludlow Griscom is hugely important to modern-day birding.  Most birders have never heard of him. This may be his first video documentary. He is important for three things.  1. Ludlow Griscom could identify birds on sight, like no one of his day.  2. Griscom championed the average birder knowing the birds in his area cold. That is why the American Birding Association  has a regional birding award named for him. 3. Most important, he ushered in the age of identifying birds with binoculars, and not a gun.
      In Raven On The Mountain's "How Many Birds Do You Need?" Ludlow Griscom is covered in Parts IV, V, and VI, with vignettes from his life from childhood to death.  Most of this stuff birders don't know, but if your birding community has a guy or a gal who knows everything, whom everyone defers to, and who makes all the rules, you know Ludlow Griscom.  He was the first of these. He was the one whom Peterson went to with a hard ID.
     You can enjoy all of "How Many Birds Do You Need?" on Raven On The Mountain's Vimeo Channel 2, right here.

It took the better part of a year to put together, but was a lot of fun.

Louis Agassiz Fuertes. Better Than Audubon? Video Documentary.

    Louis Agassiz Fuertes today is Cornell's Lab of Ornithology's patron saint.  And for good reason. He didn't invent the field guide, but Fuertes' drawings and paintings were the first ones that really were accurate enough to be able to identify birds by sight. Part IV of "How Many Birds Do You Need?" shows his progress from a childhood scribbler to the recognized Master of The Art Of Birds. Fuertes's time was the time of the Audubon movement, of Frank Chapman and his camera, and of Chester A. Reed's first ever actual field guide. You still birded over a gun barrel, but this was about to change, as the end of Part IV will show you.

You can see "How Many Birds Do You Need?" Part IV here:

or the whole six-part documentary here:

Elliott Coues, America's Famous Birder You've Never Heard Of, and Market Hunting of Birds.

       You want to call Elliott Coues "coos" or "cooz", and you are free to do either, but for his family it was "cows".  A short video about the life and habits of Dr. Coues is Part III of the documentary "How Many Birds Do You Need".  Coues, who never met a bird he didn't want to kill, actually answered the question from a student  "How many birds of one kind do I need?"  His answer was "All you can get". Today we mean in a Christmas count.  In Coues' day it meant in a drawer.
        Like all of his contemporaries, the good doctor (he was a surgeon, after all) shot birds to study them.  His graphic descriptions of avian death, and preservation were a bit much for this program, but will be the subject of another, with all the lead, blood, holes, and suffocation revealed.
      In fitting juxtaposition, Part III also brings you the market gunners of the nineteenth century.  A dollar for a Canvasback, anyone?

     You can see "How Many Birds Do You Need?" Part III here

or the whole program on Raven On The Mountain Channel 2 here

     Part III also introduces one of the men who helped bring an end to the slaughter, Louis Agassiz Fuertes.

Alexander Wilson, A Video About America's First Real Ornithologist

     Alexander Wilson, the father of American ornithology, was our first serious student of birds.. As far as a video about Alexander Wilson, any you might have found are about a modern day meteorologist. Raven On the Mountain Video has produced a 15 minute piece that outlines Wilson's life and work.  It is Part II of the six part documentary "How Many Birds Do You Need", and also introduces John James Audubon to those who know the name, but perhaps not the artist.  The infamous meeting between the two men in Shippingport, Kentucky in 1810 is discussed, as well.
     You can see "How Many Birds Do You Need, Part II" here:

or the whole 6 parts on Vimeo's Raven On The Mountain Channel 2, here

     Part I is an introduction to birding, for the uninitiated.  Humorous, perhaps, but not for the history buff in you.

Friday, September 19, 2014

Why Do Birds Bob? The Way You Move Ain't Fair, You Know.

     I recently had the pleasure of watching an Ovenbird, a Swainson’s Warbler and a Northern Waterthrush feeding on the same patch of ground as fall migration heats up here in South Florida. The feeding techniques of the three birds are distinct. The Ovenbird struts about like it owns the place and picks up food along the way. Swainson’s Warbler hops and scratches, always staying hidden under one branch or the other. The Waterthrush scratches too, but shows a characteristic bobbing motion of its nether parts as it moves about. And that is the subject of this note.

     There are several birds that bob as they walk, or even while standing. In North America the Spotted Sandpiper comes to mind. But there are others too. The waterthrushes, American Dipper, and Solitary Sandpiper all do it.  The biggest bopper of all is the Wandering Tattler. World-wide other related birds bob. Bobbing is not to be confused with tail flicking. Wagtails and pipits mostly tail-flick. So do a number of flycatchers. Bobbing involves moving more than the tail feathers.  Why birds do this has never been determined, and rarely studied, even though many have commented on it in the literature. There are lots of explanations:
  1. It flushes insects as they walk.
  2. It’s camouflage, as most of these birds spend time near running water. Predators have trouble seeing the bouncing bird next to the babbling water .
  3. It helps the bird visually, like head nodding in a pigeon.
  4. It’s signaling to a mate or companion.
  5. It’s territorial dominance display.
  6. It burns off nervous energy.
  7. It helps digestion by moving the food along the gut.  Like going for a jog after Thanksgiving dinner. 
  8. It’s a predator deterrence signal, telling predators  “I am so fit that I can waste effort doing this. You better go chase someone weaker”. Thompson’s Gazelles leap into the air (pronking) for the same reason.

All of these explanations have shortcomings.
  1. These birds eat a lot of buried prey that doesn’t respond to flushing.
  2. Any predator that can’t tell a bird from water needs to become a vegetarian.
  3. The heads in bobbing birds remain perfectly steady and are not affected by the bob at all.
  4. With the exception of wintering pipits, these birds tend to be solitary.
  5. This explanation is more believable, as juvenile birds are less vigorous at bobbing . A video by Don DesJardin shows an adult Spotted Sandpiper bobbing while tussling with a younger bird, who is not.
  6. This is absurd, as new hatchlings bob from day one. They have no energy to waste.
  7. I couldn’t find enough Scolopacid gastroenterology literature to investigate this.
  8. This is an attractive hypothesis, especially considering that the rate of bob increases as danger approaches. It does not explain why Spotted Sandpipers (video by Hector Ceballos-Lascurain) and Wandering Tattlers (video by Don DesJardin) feeding on the beach bob little, if at all.
      I endeavored to find alternative explanations, and so began reviewing my video of various shorebirds for clues to why some of them bob, and others do not. It quickly became apparent that bobbing happens with a slow walk, but not with a run or a dash. Bobbing almost always accompanied picking ones way through sticks, trash, over rocks or logs, and wading in shallow muddy water. Not so much on the beach, and certainly impossible while immersed at dowitcher depth. Bobbing in both Spotted Sandpipers and Wandering Tattlers involves the whole torso and occurs at a rate of 2-3 per second. Activity so energy consuming must be very important.

      Slow motion video of a Spotted Sandpiper revealed that at the top of a bob, the rearmost leg is pulled up with the body, after which it is carefully moved forward. Could bobbing be a means of preventing trips, stubs and possibly worse injury while walking on uneven terrain where grass, mud or dirty water prevents seeing where you are stepping? Snagging a toe on a rootlet could be dangerous. Assuring that your foot is fully out of the soup before trying to move it forward sounds like a good idea. Think of how you walked the last time you tried to negotiate a mangrove swamp or river bottomland. You raise your feet all the way out with each step. Think of the injured birds you have seen. Many of the injuries are foot injuries. Anything that could lessen this would be of value.

     This reflex may have added benefits while in thick mud. The constant up and down motion transmitted to the feet makes it less likely that toes become mired in tenacious muck. When the neighborhood Merlin is in a stoop at you, the split second gained by having your feet relatively free at takeoff can be a lifesaver.

        WanderingTattlers (video by Don DesJardin) don't fit the Spotted Sandpiper model. Their bobbing is more constant, steadier in its amplitude and doesn't seem to affect the movement of the legs. This very old video of a tattler walking in a creek gives the impression that the bird is doing all it can to maintain its footing on the jagged stones. Could tattler bobbing be related to balance? The idea is not that far-fetched. If you have ever played with a gyroscope, or repaired a bicycle wheel, you know that a rotating wheel tries to maintain its vertical orientation. This is why you don't fall over when you ride a bike. A bobbing tattler is not a wheel, but it is a pendulum. It swings back and forth with an amplitude of about 6 centimeters, at a rate of 2 swings per second. The fulcrum (pivot point) is at about the lesser coverts, making it more like a seesaw than a sideways pendulum (as the tail goes up, the “shoulders” go down). The resulting movement creates angular momentum, the force that keeps the bicycle wheel steady. Yes, it must be very small. This is a bird, not a bicycle. But a small steadying force might give the tattler just the stability it needs to find its footing and negotiate treacherous terrain. It is of interest that in videos, Wandering Tattlers feeding on sandy beaches do not bob much, if at all. Balance then on a rock, or put them in more uneven ground and the bobbing is easy to see.

        I certainly don’t advance these speculations as a definitive explanation for bobbing behavior in birds. They do, however, point out once again, what you can learn about birds from watching video.


Wednesday, July 4, 2012

July 4, 2012 In conjunction with UWOL 23, here is an explanation of FOCUS STACKING for video.

Focus stacking is a wonderful technique to allow both the foreground and background of a photo to be in focus. Although these days everyone goes "gaga" over those out of focus backgrounds, there are still people who like to see the background in focus. It adds depth and realism.

You can do this in video. It’s more difficult than with a photo, but very effective under the right conditions. The conditions are:

1. No wind (or very little). A breeze may be too much.

2. A solid tripod. Clamp down the tilt and pan. No camera movement allowed.

3. A clear view of what will be background with no foreground elements in the way, and vice versa. This takes very careful positioning of the camera.

Many shots you want to take just cannot comply with this rule. Find another shot.

4. A buffer zone. Between what will be the focused foreground and focused background, there must be a small space that will remain unfocused. This can be blue sky (the best), sand, gravel or dirt, grass, still water, rapidly moving water (like a waterfall), busy leaves, branches or bark…anything bland enough not to be noticed that it isn’t really in focus. There can be no action in the buffer.

5. Minimal movement of your foreground subject. If it moves too much it will cross the buffer zone and get visibly cut off.

OK. You have found a subject that fit’s the criteria. Now focus on the foreground and shoot some video. Next, focus on the background without moving the camera and shoot some more video, about the same length clip. If you are lucky in your composition, it may be possible to shoot a mid-range clip as well to get that tree that just isn’t quite sharp enough in either the foreground or background.

The rest is done at home. Most video editor software has garbage mattes. These allow you to blot out whole areas of scenes. They are usually used with green screens to superimpose people over landscapes but they work here too. I use Adobe Premiere which has a 4 point, an 8 point and a 16 point garbage matte. The 16 is usually needed. Load the background-focused clip. With those 16 points, outline the background trying as much as possible to keep the border you are making inside the buffer zone (step 4, above). The unfocused foreground will be black…gone.


Now load the foreground-focused clip and do a similar maneuver, outlining the foreground, and blotting out the unfocused background. Try to simulate the path of the garbage matte to the one you did for the background. Now you have two clips with only focused material showing. Superimpose them. Adjust the mattes so no black is showing. Soften the borders (remember these are in purposely unfocused areas, busy spots or edges of things where a border is not likely to be noticed), and there it is.

The technique is not perfect. A sharp eye can see where unintended unfocused material could not be matted out due to movement of the subject. In my UWOL 23 video, pause at the Siamang (the ape) clip or the pelican clip and you can see the errors around their heads. In a moving video this is not likely to be noticed.

While filming be very careful of the wind. Your tolerances of where things are placed are so close that even a little breeze waving a blade of grass that you don’t even see in the viewfinder will ruin the whole scene. Of course if you have a good wide buffer, the wind is less of an obstacle.

This technique is fun to do, and occasionally when you are out, you will run into a situation that just screams FOCUS STACKING. When it does, take a few minutes and shoot it. You’ll be glad you did.

Thursday, March 22, 2012

What is this avocet eating?


American  Avocets feed  by walking through the water and waving their beaks side to side.
Rarely can yousee what it is they are catching.  It's easy to assume that they roil the mud
and grab little critters that are buried.  But not this bird.  It actually caught a wriggling fish.
Slow-motion video shows it pretty clearly. Stop action  shows even more.  The last few
frames are sequential stills.  As the bird shifts the slippery fish closer to its mouth, it can
keep the tip relatively closed.  Notice near the end that the tip is actually  more
tightly closed than the base, and the base of the maxilla (upper jaw) bows upward to
accomodate the fish. This is exactly like a pair of jointed human fingers would have done
 the job. Quite a versatile tool.  And to think that old Count Buffon considered the avocet's
beak to be a degeneration.
To see this clip in high definition