Volume 12, Issue 4, Winter 1994


A special BCI Founder's Circle trip brought members face to face with a bat that goes fishing and much more . . .

By Malino, Emily

A special BCI Founder's Circle trip brought members face to face with a bat that goes fishing and much more . . .


SILVER WINGS glinting, a large bat flashed low over the small stream, swooping in a huge glistening arc back toward us as we stood silently on the dark bank.

"Noctilio!" Merlin Tuttle said triumphantly. We had been trying to net Noctilio leporinus, the magnificent bulldog, or fisherman bat, on more than one BCI natural history trip to the forests of Central America. Cheek pouches, pointed ears, and a blunt nose give this bat the appearance of a bulldog. But its huge feet with long claws make it the redoubtable fisherman of its popular name.

BCI founder Merlin Tuttle led our small group to Costa Rica, along with Richard LaVal and Patricia Morua, both Costa Rican biologists. Costa Rica, "wildlife sanctuary of the Americas," is
a country the size of West Virginia; but despite its tiny size, it is home to some 12,000 species of plants, 848 birds, and 237 mammal species, over 100 of which are bats. This last is an amazing number, considering that there are only 43 species of bats in the entire United States.

Noctilio is a large bat; a full-grown adult measures about 24 inches from wingtip to wingtip. It subsists largely on fish during the dry season, supplementing its diet with insects, mostly beetles and moths. In the rainy season, its diet is just the opposite: it consumes mostly insects and a smaller amount of fish. Fisherman bats also have been known to eat crabs and shrimp, and even scorpions, though in small amounts. These bats roost in hollow trees, rock clefts, and sea caves, ranging from southern Mexico through Central and South America and into parts of the Caribbean.

We had been in the cloud forest of Monteverde for several days, netting a wide variety of fruit- and insect-eating bats, but it wasn't until we got to Guanacaste, in the tropical dry forest on the Pacific side of Costa Rica, that we netted the fisherman bat in the Lomas Barbudal Biological Reserve. This sanctuary abounds with wildlife and is filled with waterfalls and rivers, shaded by trees where white-faced and howler monkeys play.

Merlin had set the mist nets across a small stream where they were in the direct path of any bat that might be fishing. We helped by weaving leafy branches into existing tree branches overhanging the stream on both sides of the net, to deflect the bats from flying around it. The net itself, about seven feet high and made of fine nylon filament, was strung across the stream on two sturdy aluminum poles buried in the ground and staked to nearby trees.

At dusk, we had had a refreshing swim in the stream and had eaten our picnic dinner before opening the mist nets. Merlin's instincts had been right; by evening's end, we had netted about a half dozen of the beautiful fisherman bats and were seeing Noctilio up close for the first time. When held close to the light, we could see why they looked silvery in flight: a thin coating of glistening oil covers their wings. The coating, similar to that on a duck's wings, keeps the bat from getting its wings wet, which would make it difficult for it to fly.

We also found Noctilio on the other side of Costa Rica. Tortuguero Lodge, on a river that runs parallel to the Caribbean, provided a spectacular fisherman bat show every evening. Off the well-lit dock at the lodge, we could sit comfortably and watch Noctilio demonstrating its talents. Minnows waited below the lights to catch insects, and when the insects flew near the water, the fish were ready. And so were the bats.

Bat after shining bat trawled through the water, often within a few feet of us. Their echolocation calls detected even tiny fish fins that emerged from the water or ripples caused when the fish fed on the insects at the surface. Long claws extended, a bat would grab a fish and scoop it crosswise into its mouth. Small minnows could be stuffed into its droopy cheek pouches, but some could barely be carried away. One bat caught a minnow close to four inches long and so heavy that it hardly could be lifted from the water.

We caught many other bats during our trip, but none as thrilling to us as Noctilio, prince of the stream and silent fisherman of the bat world.

BCI Founder's Circle member Emily Malino is a writer whose work has been featured in the New York Times, Washington Post, and New York Daily News. This was her second trip to Costa Rica with BCI. Last year she joined us in Belize.

The fisherman bat uses its huge feet to gaff fish from the water. Their highly sophisticated echolocation can detect objects on the water as fine as a human hair, including tiny fish fins that indicate a minnow just below the surface.

One of the highlights of the trip was seeing fisherman bats up close. Participants helped set mist nets over streams to capture the bats, which were then released.

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