Monday, February 12, 2007

Variations on a theme

Today is Darwin day. So I thought the best way to celebrate would be to do what Darwin did; go out and observe the natural world as he would have, with eyes and mind wide open.

Charles Darwin went to the Galapagos in 1835 and noticed that each of the island’s finches had slightly different beaks. He wondered if the different shapes might just be a "variation on a theme," specialized for different food sources (insects, grains, etc.). At the time, this was a brave new idea because it suggested how the enormous diversity of life on earth, could be the result of small gradual steps between parent and offspring over vast amounts of time. In other words, evolution by natural selection, as opposed to creationism (lame) or Lamarckism (wrong). I admire his intellectual courage just as much as his adventurous spirit.

So today, with the songs of Galapagos finches singing in my head, I'm setting out on a birding expedition, and YOU are coming with me…

Not far from where I am right now there is a remnant of mangrove swamp that I found one day on GoogleEarth. For me it is has always appeared as a sliver of heaven in a sea of hell (condos, golf courses, and strip malls).

I’ve never been able to access it. Not because it’s an inhospitable muddy tangle of roots and mosquitoes (although it certainly is), but instead because it’s “Private Property.” A few years ago, developers built a gigantic up-scale condo community, effectively cutting off access to the last slice of coastal mangrove between it and the sea. So now I’m excluded by the rules. I guess if you buy and destroy enough of something, you feel a need to protect what’s left from birdwatchers like me.

I’ll not mention the development by name here. Let’s just say it’s an epitaph to the wildlife that was bulldozed under to build it.

But today being Darwin day, I’ve decided to break the rules a bit. I’m going to put on my nicest shorts and stroll right past the gate attendant like I’m on my way to a tennis match. Once I'm in, the only challenge will be avoiding the retiree security guards, who drive residents back and forth on the boarwalks in golf-carts, just itchin to bust a whipper-snapper like me.

Before we begin, a word about the videos. Do you have any idea how hard it is to film wildlife? Now imagine doing it with a cell phone camera. As a professional filmmaker I feel a need to explain the shaky camera work. To make these videos, I hold the camera up to my binoculars, usually with fire ants crawling up my legs. Please just keep this in mind if the picture gets shaky or goes out of focus.

The title of this post is “variations on a theme.” It’s supposed to be a Darwin’s eye-view of birds. Like he did with Galapagos finches, I compare “form against function” in all the birds I encounter on a single Sunday afternoon. In each photo below, I’ve captured a specific bird's feature (form) and in the associated video I show it in action (function). QuickTime videos open in a new window.

Who wouldn't love the Anhinga. A beak perfectly suited to grabbing little fish. Also notice its cheek membrane. Like a small version of a pelican's pouch, or a nightjar's "gape" it helps funnel fish into it's grasp. It's also useful as a catcher's mitt (watch right at the end of the clip when she flips the fish into her mouth). So Cool! Anhinga fishing video

The Anhinga gets two videos because she has such a cool lifestyle. But that swimming ability comes at a cost. In order to get underwater, Anhingas have forfeited the water-repelling and buoyancy-providing oils that coat the feathers of other birds. The tradeoff is that they must dry out their wings before they can fly. They also use the time to carefully preen themselves. Hi-Rez Anhinga video (but worth the wait)

The Mottled duck has a very different shaped bill. She uses it to sift through the mud, filtering out all of the small bits of algae. The inside surface of her bill has tiny interlocking grooves and is shaped to act like a little pump as she quickly claps the top and bottom together. Duck filterfeeding video

The Roseate Spoonbill has taken the duck's bill to the next level. If some grooves are good, more grooves are better. The widened tip provides more bill-real estate and more thus more filtering. Like the Flamingo, the pink color comes from thier diet of a certain kind of bacteria they ingest. Spoonbill filterfeeding video

The Common Gallinule is not all that common. He's a robust little guy and a generalist. His bill is designed for selecting lots of different kinds of food. That's why it appears like the "typical bill-shape". Also notice from the video how high these guys float in the water. That's because of the oil on their feathers (as opposed to the Anhinga above). Gallinules browsing video

The majestic Great Egret is a symbol of stoicism. Great eye-height, and sharp lookout in the shallows, she'll stand for many minutes waiting for just the right moment to strike. The Great Egret's behavior, like it's morphology (shape) appears to be genetically inheritable. So on some level, behavior is defined by genes too. Great Egret video

The Reddish Egret is a great dancer. If the Great Egret is known for being patient, the Reddish Egret is a spaz (but they are a lot more fun to be with, that's for sure). The Reddish Egret takes a more proactive approach. She runs around, spooking the little fish into moving. The fish then want to hide in the shadows, which she provides with her wings, but it is a trick and she "knows" how to read the little fish's habits...amazing! Reddish Egret dancing video fishing video

The Louisiana or Tricolor Heron falls somewhere between the Great Egret and the Reddish Egret. She hunts for fish, walking along the shore, stalking, ....and striking. Same beak, different behavior, all defined by genes. Louisiana Heron stalking video

I LOVE the Snowy Egret. For many years I've admired those beautiful yellow feet and wanted to see them in action. Today, for the first time in my life I got to see. Watch closely, every once in a while she'll extend out her foot (especially into the crevices around submerged sticks) and jiggle it, rousing little fish and getting them out into the open. AMAZING! Snowy Egret's beautiful yellow feet in action

The White Ibis takes a different approach. His bill is specially adapted for probing into the holes of crustaceans and insects. It's also highly sensitive, packed with scent and movement sensing neurons. The body plan is similar to the egrets but look at the difference in the bills. White Ibis probing video

We almost lost this gorgeous bird. Well, a close-up view of his face may test the definition of gorgeous, but I think Wood Storks are beautiful. They nearly became extinct due mostly to loss and mismanagement of habitat. To me the Wood Stork embodies all the qualities of his buddies above. He's got the colored feet of a Snowy Egret, height of the Great Egret, bill of the Ibis, and resourceful habits of the rest. Watch as this old-guy probes the muddy shallows for a living. Wood Stork walking and probing video

This little adventure and post is meant to be a tribute the Charles Darwin. Thanks Chuck!

For the love of life, check out some of the other critters I encountered.

PS - A little story behind the story. I was knee deep in the mud when I heard my bike fall over. In the basket was my computer bag (with computer in it). I rushed up to the causeway to rescue it, but I was too late. It had floated out about 10 feet from shore. A passer by (actually the parent of the toddler who had knocked it over in the first place) snapped this photo. That's my computer in my hands dripping with water. Yeah real funny kid!

No comments: