Guano in my Garden

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Oh, my aching muscles...

By Kathleen Bander, Bats Northwest

Gardeners learn fast about the benefits of organic manure: whether it’s steer, chicken, or compost. Yet there’s a little known manure that’s credited by a growing number of gardeners as one of the best — it’s guano, and it’s produced by bats, mined from the caves where bats spend their days digesting their daily meal of thousands of insects.

Bats? You mean those strange, mysterious night fliers, those Halloween spectres we don’t pay much attention to unless it’s October 31 or there’s a rabid bat scare?

Yes, and manure aside (whew!) the reality is that bats are all around us here in the Northwest. Simply by doing what bats do well, they make an astounding contribution to humans, gardeners or not.

All 16 species of Northwest bats are bug-eaters. Studies done on Little Brown Bats, one of the most common local bats, have shown that a single Little Brown eats around 2,000 insects an hour! And they feed for hours every night throughout the summer. The fact that the number of available bugs decreases drastically in winter months, combined with our colder weather, explains why our insect eating bats must hibernate every year. And this, of course, explains why you don’t see bats except in the warm spring and summer months.

Without bats to keep insect populations down, we’d all be frantically looking for bug-free refuge. Our forests, too, greatly benefit from bats eating insects which prey upon them. To a large, though as yet undetermined extent, the health of our forests is dependent on moth-eating bats. That’s true around the world, too.

In Central and South America, bats are the primary reforesters of rainforests that have been clearcut. In fact, it is estimated that bats pollinate somewhere near 30% of all the world’s fruit.

Bats are the only flying mammal. There are nearly 1,000 species of bats, and they’re found on every continent except Antarctica. They range in size from the smallest — an endangered bat found in Thailand that’s only the size of a bumblebee, to the fruit eating bat with a six-foot wingspan found in Australia, called the Flying Fox because of its close facial resemblance to a fox or dog.

Local bats include those that people are most likely to see, Little Brown and Big Brown (though big is something of a misnomer—you could mail a Big Brown bat with a 33-cent stamp, and Little Brown bats weigh no more than two M & M’s). Hoary and Silver bats hang out in the forests.

The pallid bat lives in more arid Eastern parts of Washington, and is noted for its ability to eat scorpions without deleterious effect. Of special interest is what many people consider the most beautiful Northwest bat: the Spotted Bat. It’s elusive, and though we know it’s here because its vocalizations have been recorded, no one yet has actually sighted this bat, named for its long, silky, spotted fur.

It isn’t surprising that we don’t know much about the spotted bat: we really don’t know much about most bats. Only as humans have begun discovering how important bats are to humans have research efforts turned toward understanding these little creatures. And the more we understand, the more we learn how bats can help us. From ophthalmology, to radar systems, from reproductive science to orthopedics, research about bats is invaluable to man.

But back to guano. Gardeners knowledgeable about the use of manure in their gardens will not be surprised to learn that the microorganisms found in bat guano number in the hundred of thousands, some of which are being carefully studied. One of those microorganisms has been discovered to be perfectly suited as an oil spill cleanup agent. Researchers are excited about a myriad of other uses for bat guano.

Now that we’ve established how beneficial bats are to humans, let’s see what humans do for bats. Well, if it weren’t for humans, bats wouldn’t need to worry about the destruction of their homes and environment; they wouldn’t need to be concerned about their hibernation being interrupted and their lives needlessly threatened by humans waking them; true facts about bats would be common, instead of the untrue myths which are more common now; and they wouldn’t have to experience deaths by human hands which occur every year.

The untold story of the benefits of bats to humans has to be told. Bats Northwest was formed to do just this thing. The group gives lectures and presentations on all aspects of bats. Trained speakers are available to bring a slide “show and tell” to groups and classrooms. Bats Northwest also sponsors many research and field training projects in the Northwest.
As a gardener, you might be interested in joining the growing number of Northwest gardeners who are putting up bat houses in their yards. BNW has information on design and siting of bat houses. Call (206) 256-0406. This number has updated information on all kinds of activities, including seeing bats at their nightly balletic insect hunts at a summer bat walk around Greenlake in Seattle.

Gardeners wanting to attract bats to their gardens plant night-blooming, sweet smelling flowers, such as moon flower and honeysuckle. Moths and night-flying insects love these plants, so there’s a likelihood you’ll find bats feasting nearby. And even if you don’t, if you have these plants growing near an open bedroom window, perhaps fertilized with bat guano, the flowers will make for sweet sleep!

NWGN Archive story published February 1999

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