This Month's Story

First I see just a few birds go by, then twenty and thirty, and now a big group of fifty. They’re all going east! And they are hustling. They barely do their characteristicglide before pumping their wings and push on. They pass a group of pilings and some of the birds slow down as if they’re tired and want to rest on the pilings. But then the group movement pulls these to hurry to catch up with the flock and they all move on.

It’s Sunday and its late October.

If by nothing else, I can tell the day and time of the year by the fact that I’ve slept late and there’s a definite nip in the air. It’s almost eight o’clock, I’ve showered, I’ve shaved and now I’m outside. I’ve just collected the Sunday papers from the driveway and walked around to the front of the house. Here I’ve stopped, undecided whether to go back inside or stay on the porch. All of this has taken a lot out of me and I just stand there.

There’s a slight fog, not much, just enough to give the new light a slight haze, a muting that softens my morning view of the Sound. There is no wind and the water is exceptionally calm, a blue silver that matches the sky.

In the distance a slight line marks the horizon, but otherwise you can’t tell the difference between sky and water. High as the horizon is, one might think the line some optical corollary of the scene rather than the actual separation of sky and water, but the silhouettes of two distant shrimp boats sitting on the line state that it is what it is. Below it is water, above it is sky.

I grab a porch chair and decide to sit and enjoy the scene. Jennie is with me and she lets out a loud humph! as she drops herself down on the wooden deck beside me. Stella will be up soon to make breakfast and bring me some coffee. I hear her inside starting to move around.

So I’ll sit here and muse about what I see. There is a reason for the water being the same color as the sky. It’s because when I look at the water, I’m really seeing the sky; or at least its reflection. The water of the Sound gets its light from the sky and the color we normally see when we look at the water surface is sky light that has been run through a bunch of filters.

But the amount of sky light that colors the water varies according to two optical rules according to the time of day.

At this time of the morning, the sun is less than 35o above the horizon so I am getting the direct reflection of the sky light. This effect has a pleasant name, fresnel reflection. It means that the “reflection coefficient of the grazing angle approaches unity.” Or to better state it, almost all of the sky’s light is being reflected off the water. Very little is entering the water and, if we were swimming below the surface, it would be quite dark.

Later in the morning as the sun rises higher in the sky, some light will start penetrating the surface and the water at depth will start to have light. This is covered by Snell’s law, which is easier to compute than Fresnel’s Law but is much more boring.

What is interesting is that when this happens, the color of the water’s surface will be a mixture of reflected sky light and the upwelled light from the water below the surface. Since this upwelled light has to travel through water rich in tannin and detrital material, the water we see at the surface, rather than being the blue it would be if it were sky light alone, has a brownish color that is a mixture of the sky and upwelled light. Of course if there is a lot of detrital material, the water will be brown and opaque.

I quickly sit up in my chair. A line of pelicans is going by. It’s their morning rush hour and my thoughts of optical jargon are quickly forgotten.

First I see just a few birds go by, then twenty and thirty, and now a big group of fifty. They’re all going east! And they are hustling. They barely do their characteristic glide before pumping their wings and push on. They pass a group of pilings and some of the birds slow down as if they’re tired and want to rest on the pilings. But then the group movement pulls these to hurry to catch up with the flock and they all move on.

I wonder what the hurry is and where are they going?

Is there some person to my east sitting on his porch watching groups of pelicans heading west?

If so, how far away is he?

Where is the point between us where all these birds converge? And why there?

Isn’t the fishing just as good here?

The reason for all of this escapes me. Later this afternoon the birds will come back by the house again, heading west. Not in such big groups or in such a hurry, sort of sauntering like their bellies are full and in truth they are. Somehow to my east, they have found food. Where to my east, I don’t know, but their actions indicate that this is so.

Stella comes out and hands me a cup of coffee. She stares at a particularly large group of passing birds. On a Sunday a couple of weeks ago I had mentioned the morning event to her. She had stood with me and watched to see them go by. None had come by. Her remark on that day was that their non–appearance might have been because “it was Sunday.”

Now on another Sunday they are going by and I wait for her to say something. She watches for a long moment then goes inside to fix our breakfast. As she leaves she gives me as good an answer as any.

“They’re probably all going to Mass over in the Bay.”

I lean back and relax. Her remark notwithstanding, I know I will be fed and fed well.

Stella only fixes me breakfast on the weekends and then it’s a treat. Eggs, or waffles with maple syrup, or both, thick bacon or spicy sausages, or both, home fries, grapefruit, orange juice, hot rolls with lots of butter and jam, coffee and Jennie under the table to keep my feet warm. My stomach grumbles and I try to not think about breakfast and just watch the birds and the water.

I’ve noticed the birds have been coming later and later each day and it is true that many days they don’t come at all. Maybe they know something that I don’t. It slowly dawns on me that they are on sun time not clock time. The sun is coming up later and later each day and so they adjust their commute to start later and later each day.

There is a mystique to the instinctive thinking process of birds. Let me give you an example. Years ago I was using a helicopter to investigate a large boil of water that occurred periodically in the Strait of Gibraltar. The boil only occurred in one place and only at a certain time in the daily cycle of a spring tide.

On the day of the flight, we checked the area before the start up time of the boil and then, since we had an hour or so to kill, took the helicopter to loiter near the whitewashed town of Marbella and to idly slip between the hills along the shore.

Then, when it was time for the boil to begin, we darted back to the Strait. Just as we got there and were about to lower our instruments into the water, the pilot pulled the copter up to a hundred feet and gestured.

Rushing from both shores into the area of the boil were hundreds on thousands of birds. Some bell had sounded in their minds and now, where before there had been no birds, there were thousands coming into the area to feast on the largesse offered up by the roiling water.

Maybe this is what is happening with these pelicans. The reason for the hustle of their morning flight must have something to do with their breakfast and the fact that they haven’t eaten since yesterday afternoon. They’re hungry.

Pelicans fish by seeing their prey. Since they have to see below the surface to do this, they only fish when the light is at a sufficient angle to penetrate the water.

Somehow, in their minds, they had worked out Snell’s and Fresnel’s physics and were using this knowledge in a way that was important to them. That is, to know when the newly rising sun reaches that critical angle so that as early as possible they can be at the right place to begin their daily hunt for food.

Stella is calling that my breakfast is ready. I pick up the Sunday papers and, with Jennie close behind me, go in and start the day. I may not mentally compute Snell’s law, but I follow the same basic instincts for meals.