Ecological niches?

On the deck of our home in Mount Vernon at dusk, I often find myself looking skyward and admiring the swallows at work. Their wing shape is so distinctive. They define the word “flit” as they zigzag across the sky. I have imagined that each vertex in their path marks their detection of some flying insect and BOOM, one more West Nile carrying mosquito bites the dust. So I am very fond of our swallows.

Of course things are very different in the tropics. Kris and I were in downtown Kandy at dusk last weekend and we were waiting for our tuktuk driver to pick us up. We had a few minutes and my eyes went skyward and I noticed that there appeared to be swallows at work on the local mosquitoes. These birds also had a distinctive, vaguely familiar, wing-shape but it was not the wing-shape of a swallow. It was difficult to judge distance and so it was a little difficult to judge the size of the birds. But after watching for a bit, some came closer, some were farther away, and I realized that these birds were HUGE. Despite the low light level, I could tell that these birds were all black. And then it hit me. These were not swallows. These were not even birds. My internal pattern recognition software finally identified the wing-shape. These were enormous, black, hairy, bats!

Fruit bats to be precise. And they probably were not after insects as, as you might expect from their name, their primary food is fruit. Perhaps they were just passing through. Western culture tends to focus on the fact that bats appear to us to be flying rats. To be fair. since bats are mammals, they can carry certain health risks for humans that birds do not, like rabies (though Avian flu may be changing that distinction).  Some Asian cultures tend to have a much more positive view of bats than Western cultures. In Chinese culture, the bat is a symbol of good luck and prosperity, for example, and images of bats are found everywhere in China. I’ve just learned that Sri Lankans are not particularly fond of bats. For one thing, they eat the delicious fruit that the farmers have worked so hard to cultivate.

As a geographic aside, one of the most magnificent natural phenomena I have ever witnessed was at Carlsbad Cavern in southern New Mexico. Every evening at dusk, thousands of small bats exit the cave. It is dramatic. For a long time, nothing happens. Then, as if someone opened a valve, the air near the cave opening becomes so thick with bats that the assemblage of bats appear to be a liquid. This liquid forms a tornado-like vortex as the bats spiral out of the cave and gain altitude. Then, a liquid rope sprouts from the top of the tornado and the rope elongates to the south as the bats go off to bring death and destruction to the mosquitoes on the Rio Grande. You really should add a trip to Carlsbad at dusk to your bucket list, if you haven’t already seen this magnificent sight.

I will admit that the Sri Lankan fruit bats are so huge and so ugly that they bring our certain primordial fears from some dark recess in my brain. As much as I know intellectually that the bats are positive contributors to the local ecology and that they are neither carnivorous nor blood-sucking, I can not fully dispel my unease at the sight of these fruit bats. Someone filming a Dracula knockoff can come to Kandy to shoot some inexpensive stock footage. Their “hanging length” of the local fruit bats appears to be about two and a half or three feet. Their wingspan is about four feet. The size of the fruit bats can work to the disadvantage of the bat. You can sometimes see them hanging upside down from trees, sleeping during the day. We saw one that appeared to try to hang from a 240V electrical line feeding a house. Unfortunately for the bat, it was so long that its body spanned the distance between the line and the return and it was fricasseed.

I wonder if it tastes like chicken?




  1. John Pepple said,

    October 31, 2008 at 8:07 pm

    I believe congratulations are in order for you, Tim!

    Here’s some old business. This idea of moving from the left lane on a freeway into the exit lane and then trying to get back onto the freeway: what was the purpose of this?

  2. Tim said,

    November 5, 2008 at 12:41 pm

    Thanks for the congratulations. I am both honored and humbled.

    The purpose of the freeway off ramp maneuver was to get through the jam at the off-ramp as quickly as possible. This is a variation on, I think, the crisis of the commons. The off-ramp maneuver did seem to to accomplish its intended purpose for the individual driver (to get through the jam most quickly). However, as the drivers tried to use the maneuver to optimize their speed individually, they created a traffic jam with all the lane changing, thus slowing everyone down, including themselves, collectively.


  3. February 18, 2009 at 8:15 pm

    […] “shift change”  is not the experience one has at Carlsbad Caverns, but it is impressive in its own […]

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