Damage Prevention and Control Methods

White-crowned sparrow, Zonotrichia leucophrys (left) and golden-crowned sparrow, Zonotrichia atricapilla (right)

Exclusion

To protect flower seedlings and home vegetable gardens, grow plants under frames covered with wire or plastic netting.

Habitat Modification

Since crowned sparrows usually feed within a few yards of secure cover, the elimination of all useless brush piles, rolls of wire, and stacks of wood around vulnerable crops is desirable. Eliminate weedy borders along fields. Destroy fence rows and unnecessary shrubbery if occupied by sparrows.

Frightening

Historically, the most widely used sound devices for minimizing crowned sparrow depredations have been the automatic propane exploders. These units should be moved every day or two to prevent the birds from becoming habituated to the sound. Shell crackers fired from a 12-gauge shotgun, bird bombs, and whistlers discharged from a 6-mm flare pistol are commonly used to frighten spar-rows from damaged fields. Some growers have reported limited success with raptor-mimicking kites tethered to stationary posts positioned along crop borders. Avitrol^® Mixed Grains (0.5%) is a toxic chemical that produces flock-alarming reactions in birds that ingest a sufficient quantity. It is currently registered in California to control crowned sparrows that may damage sprouting crops. Prebaiting is usually necessary with untreated grain (fine chick scratch) to establish a feeding pattern. The prebait should be placed in trays in the same area where the treated bait will be exposed.

Avitrol^® treated chick scratch must be exposed in trays only. Set trays out in the field after the crop is planted and before crowned sparrows have moved into the area. Each bait tray should contain one part Avitrol^® Mixed Grain concentrate with two to nine parts of untreated fine chick scratch. The quantity of treated bait to expose per tray will vary depending on the amount taken by crowned sparrows during prebaiting. Several trays should be placed where the birds are normally observed. Bait should be replaced if it becomes water soaked or depleted.

Repellents

Methyl anthranilate (Fruit Shield^®) is currently registered for ornamentals, corn, sunflower, a variety of fruit crops, and structures.

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Toxicants

None are registered.

Trapping

Crowned sparrows are usually quite easy to trap using lily pad or clover-leaf traps and have been taken by modified Australian crow traps. Use milo or finely cracked corn as bait.

Figure 2. Lily pad and cloverleaf traps.

The lily pad trap and cloverleaf trap are easy to set up and peg to the ground (Fig. 2). They are effective in catching small numbers of crowned sparrows. These traps are usually 3 feet (1 m) high and 3 feet (1 m) wide.

Australian crow traps are used to capture crows, magpies, and ravens. The traps can be modified by changing the entrance, and used to capture crowned sparrows, starlings, blackbirds, house finches, and house sparrows (Fig. 3). Minor modifications can be made to fit the trap on a truck or trailer. The basic design of the trap, however, should not be changed.

Proper trap location is one of the most important factors in achieving good results. Observe the problem area to determine flyways and resting, perching, and feeding areas before placing traps. Place traps in open areas where they can be easily seen. Traps have been most effective where birds enter fields and orchards, or near resting and perching sites.

Trapped crowned sparrows serve as decoys to other birds. Decoy birds are usually essential in attracting other crowned sparrows. Use one to five live decoys, depending on the size of the trap. Provide food and water at all times to keep decoys alive and to make the trap more attractive to wild birds. Canary grass seed, wild bird seed mix, or chick scratch work well to maintain decoy birds. Install 1/4-inch (0.6-cm) dowel rods to serve as perches, especially in larger traps. Perches should run the full length of the trap, about 1 foot (30 cm) from the sides and half-way between the top and the bottom of the trap. Cold winds or hot sun can stress trapped birds. Fasten burlap to the sunny side of the trap to provide shade in the summer. With small traps, the captured birds may be removed by hand. Birds can be removed from modified Australian crow traps by hand or with a small net. Several birds can be removed by cutting a 6 x 6-inch (15 x 15-cm) exit hole that is easily opened and closed in an upper corner of the rear of the trap. Place a small holding cage on the out-side of the trap over the open exit hole and herd the birds from the trap into the holding cage. To euthanize the birds, place the holding cage in a plastic bag and inject carbon dioxide through a hose until the birds are dead. Burn or bury the dead birds.

Important Assembly Instructions:

Place end panels between side panels; otherwise, top panels will not fit properly. Note:

a. Reinforce this area with a 2 x 4 x 16-inch (5 x 10.2 x 40.6- cm) piece of wood. This provides a greater surface area for the entrance to rest on.

b.Place a small door in this area for removal of trapped birds.

Materials Needed For Trap:

15 boards -1 x 4s, 8 feet long (2.5 x 10.2 cm, 2.4 m long)

25 boards -1 x 4s, 6 feet long (2.5 x 10.2 cm, 1.8 m long)

4 boards -1 x 1s, 8 feet long (2.5 x 2.5 cm, 2.4 m long)

1/2-inch exterior plywood - 16 inches x 8 feet (40.1 cm x 2.4 m)

1/2-inch mesh aviary wire -3 x 80 feet (0.9 x 24.4 m)

2 hinges

staples