Bats

Strange flying creatures we see at night, if at all,

With webbed wings, tiny feet, eyes quite small,

Usually when we bring ourselves to think of bats,

We associate vampires, Dracula, and black cats,

May shudder as they flit across darkened sky,

Mostly on Halloween night as dead leaves fly,

We think of them as one or two of a size and kind,

But if we look there are many varieties we find.

Some are even quite active during bright of day,

Old World tropical fruit bats’ eyes find their way,

Assisted by tongue clicks even humans can hear,

Timed echoes find objects both far and near.

But their development of sonar is rather crude,

Compared to what some bats from sound extrude.

Some smaller species are genius with technology,

Glean from it far more than some silly mythology.

Brains, electronically miniaturized to size of dime,

Programmed to decode echoing world in real time,

Faces, distorted, gargoyle shapes that hideous seem,

Are exquisitely fashioned, ultrasound to beam.

These bats have chosen their environmental niche,

Major problem — navigate darkness black as pitch.

Often roost deep in caves with absence of light,

Must find their way in and out on every flight,

Among thousands with quite similar goals,

All using echo-location in navigation roles.

How to distinguish their echo from another?

Was it returned from near object? One farther?

Is it moving toward or away, if so, how fast?

How audible is echo from ultrasound cry cast?

Originating cry has to be a super strong bellow,

Echo’s lessened to fourth power, and that’s low!

Their auditory system is very delicate, in fine tune,

Why isn’t it damaged?  Cry’s no way a soft croon.

Higher pitched than dog whistle, it’s ultra-ultrasound,

We know by the frequencies our electronics found.

Frequencies out of our hearing range, that’s good,

For their cries’d be deafening, most definitely would.

High pitch is a must, frequent sound waves to return,

Update mental image very often, no time to burn,

For they fly through treetops, occupied air space,

Chase bugs, avoid collisions like fighter jet ace.

Some bats have closing muscles in their ear,

Shut hearing to send, open for echo to appear.

Muscles attach to the hammer and stirrup bones,

Close, send, open, receive, like walky-talky phones.

Some move their ears rapidly forward and back,

But could be technique using Doppler to track.

Now let me explain — Doppler effect is the name

Given to waves, sound or electromagnetic, the same,

The wheeeeee-oooooooo of a motor speeding past,

The shift in how long between waves, intervals last.

Some bats use this effect when they’re on the go,

And among thousands to know their own echo,

Cry, like very short wolf whistle, to clarity seek,

Makes echo of varying pitch, any moment unique.

Higher pitched echo parts say distance is more.

Lower pitch, closer object, the rest, noise to ignore.

A common little brown bat, Myotis, its name,

Emits 10 “clicks” per second in cruising frame,

Increases up to 200, tracking insects on the fly,

Like disco strobe would give us light to see by.

Some bats continuously change pitch they send,

As an object moves, such that its echoes tend

To return at fixed pitch heard most efficiently.

Imagine coordination to do this sufficiently.

Different groups employ wolf whistle ultrasound,

Some form of Doppler shift or mix both around.

Some emit a fixed hoot, long by standards of bat,

Wolf-whistle at the beginning or at the end of that.

If strangeness appears in the image of their world,

Some bats recognize patterns as they’re unfurled,

Each successive ultrasonic image of the night,

Should be same as before or its difference slight,

So if echoes are too far out of expected order,

Such that they don’t fit within a realistic border,

Assume it’s noise and deserves quick discard,

For real world objects don’t jump awry-ward.

A bat keeps a mental image of its dark world,

As through it like a speedy butterfly, it’s hurled,

With reflected audible updates continuous,

Our reflections are similar, only luminous.

Probably knows nothing of sonar and such,

Just tries to make its living using deft touch,

 With evolutionary precision, its world it hears,

Had a million tiny assists to its germline’s ears,

Like our world through wondrous eyes we gauge,

With their million tiny tweaks via geologic age.

So this Halloween, with your costume a-bustle,

As about you the dead leaves whirl and rustle,

Shadow hits your eye, you look up in the night,

See something flitting by, in and out of the light.

Smile, you’re on Candid Sonar by a little brown bat,

You’re an echo — you, Dracula, and a black cat.

This poem was inspired by a section of Richard Dawkins book, “The Blind Watchmaker,” where he discusses the effects of evolution on bats use of sonar.