This is one of the oldest methods, and has been in use since time immemorial. It includes measures, such as the collection of egg masses and other inactive stages, the removal and destruction of infested parts or whole plants, the beating of drums or tins and trenching. This method can prove to be effective during the initial stage of the pest incidence and when practised as a concerted effort by a large number of farmers in a particular area. Mechanical devices can be grouped according to the function of the device, and have probably been used more than any other control method.
Traps
Trapping is the oldest profession known to man. Traps were originally designed to capture animals for food and fiber rather than to control their numbers. They can be very simple, improvised traps, such as dead falls, or sophisticated traps that combine lights and gas chambers, where animals can be killed upon capture. Large baited-cage traps are probably the most efficient kinds for catching large numbers of animals, and are used with considerable success to control bird populations.
Frightening Devices
Various means have been employed to frighten pests away from crops, and usually work best for bird pests. Frightening devices can be grouped according to their means of control. Gas and sharpnel bombs are efficient in root areas and are selective to the species using the roots. It was reported that 300,000 redwings, grackles, cowbirds, and starlings were killed with bombs in two consecutive seasons. They found only one dead bird of another species. Roost bombing is hazardous and should be perfirecrackers are also used to frighten birds from fields. Gas exploders are usually placed to project the sound over the field. Loudspeakers are sirens are used to scare birds from concentration areas. Although birds are frightened and made to fly, they often move only from one location in the field to another. Another disadvantage to using sounds of this type is that birds become accustomed to them if they are applied for long. The time for sound conditioning depends on the species; some may condition to the sound quickly (redwing blackbirds, cowbirds), whereas other habituate more slowly (starlings yellowheaded blackbirds). Another method that uses amplified sound is to broadcast alarm sounds and distress calls. It is best to direct the proper alarm sound to the proper species. As an example, blackbirds will not respond to starling sounds, but starlings will respond to blackbird sounds; cowbirds are immune to most sounds.
Ag.
Technologies
(Pest Mgmt.)
