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A ROBOT alligator has been developed by fish farmers in Louisiana to scare
birds off their ponds. When the swimming robot identifies a bird sitting on the
surface, it tries to ram it, or blasts it with a harmless water canon.

Birds can be a menace to fish farmers. “Last winter, it became a real
problem—we lost pretty much the whole stock to pelicans—around
$16,000 worth,” says Randy Price at Louisiana State University. The
university’s 5-hectare lake normally teems with catfish and crayfish. “Some of
the birds were picking up such big fish, they could hardly fly away with them,”
Price adds.

To scare them away, fish farmers go out in boats and fire blanks, says Price.
But the birds don’t leave for long. So Price developed a more effective
bird-scarer. Supported by two polystyrene floats, two rotating paddles propel
the robot across the lake at speeds of up to 5 kilometres per hour. A large
solar cell on top of the robot recharges the bird-scarer’s batteries, so that it
can patrol late at night.

Collision sensors detect when the robot hits the opposite bank of the lake.
It then reverses slightly and does 180° turn. Because the turns aren’t
always perfect, and the robot gets blown around, it eventually covers the entire
lake, says Price.

A video camera and simple image processing software allow the robot to hunt
birds. “If it detects a white region—a bird—it steers towards it,”
says Price. Should the bird stray into the middle of the image, the robot takes
a potshot with its on-board water canon. Price now wants to dress the
$1000 craft up as an alligator in time for the return of the pelicans in
November.

But Ben Ross of Scottish Natural Heritage in Lanarkshire warns that the water
canon might baffle the birds more than scare them. “The key thing with
deterrents is that they have to be relevant and behave realistically toward the
pest species.”