Damage Prevention and Control Methods
Exclusion is generally not feasible to protect crops from magpie depredation unless crops are of high value or the area to protect is relatively small. Nylon or plastic mesh netting can be used to cover crops, but netting is expensive and labor-intensive, making it uneconomical to use in most situations. Netting can be used to protect individual trees and is most appropriate in small areas where depredation is extreme.
Exclusion is an ideal method to keep magpies from livestock when it is economical to do so. Poultry nests and young kept in fenced coops and feeding areas (maximum 1 1/2-inch [3.8-cm] mesh) are relatively safe from magpies. Lambing pens can reduce the incidence of eye pecking. Livestock with open wounds or diseases can be kept in areas that exclude magpies until they are healthy.
Predation on poultry often increases during magpie breeding season. Raids of increasing intensity can often be tied to a few offending breeding pairs with young. Removal of their nests can effectively reduce predation. If removal takes place early in the nesting season, magpies may renest, often in a completely new area.
Clear low brush to reduce nesting habitat in areas where several black-billed magpies are regularly concentrated and cause significant yearly damage. This method reduces habitat for all wildlife, however, and should be carefully considered before under-taken.
Removing or thinning roost trees will force magpies to find new roost sites. The primary factor to consider is the number of trees that need to be removed to satisfactorily reduce cover so magpies will relocate. Usually, the removal of only a few trees will discourage magpies.
Frightening devices are effective for reducing magpie depredations to crops and livestock. Several methods are used to frighten birds and are explained in greater detail in the chapter on Bird Dispersal Techniques in this manual. A combination of human presence, scarecrows, pyrotechnics (fireworks), and propane cannons provide a good frightening or hazing program and can reduce depredations significantly. The cost of using each of these techniques must be compared to determine the most effective combination to obtain the greatest benefit-cost ratio. The success of these devices varies greatly with location, availability of alternate food supplies (such as insects and wild mast), and how the techniques are used.
In a hazing program, the periodic presence of a person is important because it reinforces most techniques. The mere presence of a person will normally keep magpies at a distance, especially where magpies have been hunted.
Frightening devices such as scare-crows and other effigies, eye-balloons, hawk kites, and mylar (reflective) tape are used to deter magpies. Most are effective for only a short time, but their effectiveness can be extended by moving them regularly. The human scare-crow is still one of the most effective frightening devices. Painted eyes on both front and back of the head and arms made of flaps that blow in the wind will increase its effectiveness. Place scarecrows at regular intervals in the threatened area (one for every 2 to 10 acres [1 to 4 ha]) along with a combination of other frightening devices.
Pyrotechnics or fireworks can be used to repel animals. These explode, whistle, or scream after being ignited. Typical pyrotechnics are shell crackers, rope firecrackers, and racket and whistle bombs. These can be purchased from suppliers, but some states require a permit from the state fire marshal. Shell crackers are probably the most widely used and are shot from a 12-gauge shotgun, travel about 75 yards (70 m), and then explode. The 15 mm pistol launcher, however, is more economical, easier to carry, and allows reports and whistle and racket bombs to be shot. The variety seems to be more effective for magpies. The projectiles travel from 35 to 70 yards (30 to 65 m) depending on the style. These can be shot whenever magpies are seen in the damage area, but conservative use will reduce acclimation. Check state and local laws regarding pyrotechnics.
Propane cannons fire loud blasts at timed or random intervals. A variety of styles are available. Conceal cannons in threatened areas, move them every 3 to 5 days, and use sparingly to avoid habituation. For magpies, the blast interval should be no greater than one every 2 minutes and the interval should be varied. Shooting a few magpies with a shotgun and using pyrotechnics will increase the effectiveness of propane cannons.
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Methyl anthranilate (Fruit Shield®) is currently registered for ornamentals, corn, sunflower, a variety of fruit crops, and structures.
None are registered.
Trapping is effective in reducing local magpie populations and damage where they have concentrated in high numbers because of food availability or winter conditions. Several trap designs have been successful in capturing magpies. Traps made of weathered materials are most successful, but still require time for magpies to become accustomed to them. Traps are most effective in areas frequented by magpies or along their flight paths into damage areas. Consult federal, state, and local laws before trapping.
An effective trap design commonly used for capturing magpies is the modified Australian crow trap (Fig. 2).
Figure 2. Modified Australian crow trap for magpies: a) entrance ladder (top view); b) side panel; c) top panel; d) end panel with door; and
e) assembled trap.
- 28 8 foot, 2 x 2-inch boards
- Cut these into: 12, 8 feet; 10, 6 feet; 4, 4 feet; 4, 34 inches; 6, 30 inches; 2, 22 inches; 17, 12 inches
- 1 8 foot, 1 x 6-inch board 56 feet of 4-foot-high, 1 x 2-inch wire mesh 24 4 1/2 inch bolts with wing nuts and 2 washers b 2 small door hinges
- 1 door hook latch or locking style 3 1/2 inch nails, staples, haywire
Construct the entrance ladder. Cover both ends with wire-mesh pieces 7 x 16 inches. Make two side, top, and end panels. One end panel is constructed with a support beam in the center (as pictured in the assembled trap) and the other with a door. Cut and tightly staple wire mesh to the inside walls. Cut or file any sharp projections that will protrude into the cage. Assemble the trap, holding it together with baling wire. Drill 10 holes in the end panels (shown in d) and through the adjacent panels. Put bolts through these holes with washers on both sides and secure with wing nuts. The side panels and entrance ladder can be snugly held to the top panels with haywire or bolts.
This is an inexpensive decoy trap that becomes more effective after the first birds (decoys) are caught. The standard measurements in figure 2 can be modified to facilitate transportation and storage, but the dimensions of the ladder openings or slots must remain the same. The trap can also be built to fit onto a trailer for transporting from one site to another.
The modified Australian crow trap has been used effectively in Washington and Oregon by baiting the trap with a red-colored, dry dog food. Initially, place dog food on the middle slat of the ladder until the first magpies are caught. Inside under the slots, place 10 pounds of dog food and water. Carrion, such as a chicken carcass or a road-killed rabbit, can also be used as an attractant. Check the trap daily, remove all but two magpies, and replace bait and water as needed. Non-target birds that are captured should be immediately released unharmed. This trap can take several magpies, but it does require some time and expense to maintain properly.
1 1/4-inch reinforcing rod 12 2/3 feet long
1 2 foot 6 inches x 12 foot 8 inches piece of 1-inch welded-wire mesh
2 2 foot 6 inches x 4 foot wire mesh (cut to fit top)
1 2 foot 6 inches x 3 foot 6 inches wire mesh (cut and tapered for funnel)
3 stakes about 10 inches long with ‘U-shaped’ heads
Bend the 1/4-inch rod in a circle and weld. Attach the 12-foot 8-inch wire b mesh piece to the rod with haywire and crimp the ends of the wire mesh around the rod. Cut out the funnel, shape, and attach to the ground-side, inside wall with haywire. Cut out the wall according to the size of the tunnel opening. Cut out the rectangular opening (12 x 16 inches) on three sides opposite the funnel, but leave the fourth side as a hinge for a door to remove magpies. If light-gauge wire is used, an additional reinforcing rod around the top and on the sides may be needed to make the trap sturdy. Cut out c the top and attach. Stake down the trap in the area to be trapped.
Another trap design that has been successful for trapping magpies in Alberta is a circular-funnel trap (Fig. 3). Prebait the area to be trapped. After magpies start feeding, place the trap nearby where they can adjust to it. To attract magpies into the trap, place a line of bait leading into it. After the first birds are caught, remove all but one or two decoys and any remaining prebait. Keep trapping an area until most magpies are caught and then move the trap to a new location. This trap is probably not as efficient as the crow trap for catching large numbers of birds, but it is not as cumbersome and may be more effective at trapping magpies prone to feeding on the ground.
Padded-jaw pole traps can also be used to take a few offending magpies. These are leg hold traps, No. 0 or 1 coil or jump spring, placed on 5- to 10-foot poles that are erected in threatened areas (Fig. 4). They can also be placed on routinely used perches. Traps do not have to be covered. The jaws need to be well padded with foam rubber or cloth and wrapped with electrician’s tape to allow the leg to be snugly caught without breaking it. Run a heavy-gauge wire through the trap chain ring and staple the wire to the top and bottom of the post, allowing magpies to slide to the ground and rest. Both sides of the trap should be anchored with fine wire or thread to give the trap some stability. Other perches that cannot have traps placed on them should be removed or covered with tack board or porcupine wire to prevent magpies from landing. Traps must be monitored frequently and placed in areas where nontarget