The first trap widely used by banders (and still
popular) was a funnel type, known as the government sparrow trap, because it
was designed in 1912 by the Department of Agriculture for farmers trying to get
rid of house (or "English") sparrows. It is good not only for these
pests (which nearly all banders despise) but for many of the 30-odd species of
native American sparrows (which are beneficial and a delight to the eye and
ear) and a wide variety of other small birds. Lured by such baits as seed and
bread crumbs, the birds push through the first funnel, which ends in a
horseshoe of converging wires. What looks like "the way out" proves to
be another funnel, leading to a second compartment, so the birds are
double-trapped. When the bander is ready to collect them he shoos them into a
gathering cage which may be permanently attached or hooked on over a small door
opening when needed.
One of the simplest traps is bottomless and
box-shaped, made of hardware cloth, welded wire or fine-gauge (1/2-inch to
3/4-inch) chicken wire. It is propped up over the bait or the nest of a
ground-breeding species. One long edge is supported by a stick (which may be
hinged for quicker action) with a string attached. When a bird is beneath the
trap the bander pulls the string.
Still relatively simple, but automatic so that it need
not be watched continuously, is a cage-shaped trap with a hinged
"doorstep" set at a slight upgrade. When the bird jumps on the step it
trips an attached trigger wire, and a sliding door slams down behind it. Named
for the late Miss Jessica A. Potter of Los Angeles who designed it in the
1920s, the Potter trap has been made with many modifications, notably multiple
cells—one trapped bird tends to attract others whose curiosity lands them in
the clink—and glass backs.
Water is a good bait, so in the chardonneret trap
(French for goldfinch) there are tiny pans mounted on cocked trigger bars which
spring an overhead door when a bird drops in for a quick one.
Deservedly popular is the well-named all-purpose trap,
shaped like a double-letter S and modified by Seth H. Low of the FWS from an
earlier clover-leaf design. The sides are hardware cloth, 2 feet high and 10
feet long; the top can be hardware cloth or chicken wire. In a permanent layout
the trap can be set on concrete to discourage rodents from digging their way in
and out. In any setting it works best when there is a shallow pool at one end:
the important thing is to have a slow, steady drip of water into the pool to
attract attention. A galvanized pail with a small hole, half plugged with a
loose-fitting nail, will get as many birds as a more elaborate hydraulic
system. The birds get in through a narrow, funnel-shaped entrance.
Even so wily a bird as the crow still has markedly
limited intelligence. Modifications of an Australian crow trap are springing up
in U.S. gardens: usually 6 feet high and 10 feet square, they have panel-shaped
entrances at the top. The crows hop down to feed on corn on the cob.
Surprisingly few of them are smart enough to try to fly upward and out the same
way. If they do they are discouraged by the jangling of wire coat hangers
strung just under the entrance—which did not deter them from getting in.
Exotically named in keeping with its origin and
purpose is the Bal-Chatri trap, developed in the Orient for catching falcons
and adaptable to most birds of prey. A cone-shaped cage, it holds live bait—one
good use for house sparrows, though a house mouse is best. Attached to the top
are dozens of nooses, originally of strong silk, now usually of fine nylon
leader. Banders driving along a country road spot a sparrow hawk (American
kestrel) perched on the wires ahead. Almost beneath the bird they slow down;
the passenger opens the car door and drops the trap on the road shoulder. By
the time they stop, 100 yards beyond, to look back, the hawk often has his feet
caught in a cat's cradle of nooses.
In Europe whole gardens have been converted into traps
as elaborate and durable as Hampton Court Maze, but in North America the more
costly and permanent layouts are generally reserved for waterfowl. An
adaptation from the Dutch, who gave us the word decoy, is the decoy
pipe-actually a tunnel, up to 150 feet long, over a curved "pipe," or
waterway, dug out as an extension of a shallow pond. The sides have footings of
stone or lumber; above that, to a total height of 7� feet, is wire. At the
inner end, around the curve and invisible from the pond, is a catching pen 4 by
8 feet, with a gathering cage attached. Baited with shelled corn outside and
cob corn inside, the pipe may take hundreds of ducks at once.
The ambitious Colorado trap, usually 25 by 50 feet,
consists of netting set over and around steel posts standing in shallow water
at a pond's edge. The entrances are on the land, where the trap extends about
four feet over a feeding lane. Birds are first baited in with barley spread
along a quarter of a mile of shore line. The feed is gradually concentrated to
get the birds into the trap. After feeding, they plop into the adjacent water
to drink and rest—and wait to be driven into gathering pens.
In all, probably as many ducks are caught for banding
in simple, portable traps, with wire sides and top which swivel readily (on
doweling, bamboo or Duralumin rods) for folding and portability. One of the
handiest, only 2 by 3 by 1� feet, designed by the FWS's law-abiding John J.
Lynch, is unabashedly called the Maryland violator trap in honor of the
lawbreakers from whom it was copied.