The author once with complete success contrived and operated a mechanical “bouncer” to meet a particular and aggravated instance of bird trespassers. In case of interference with any desired tenant or prospective tenant by rivals for the same bird house, the interfering birds may be driven away by this device.
[Illustration: Figure 1. Discouraging the Uninvited Guest.]
One end of a stout cord is attached at some point close below the bird house. To this cord a rag or a piece of waxed paper about man’s-handkerchief size is tied as conspicuously as possible at a distance from the fastened end of the cord about equal to the height of the bird house. The cord’s free end is then carried through a window of your own house from which there is a convenient view of the bird box. The end of the cord is fastened inside the window where it can be easily reached and jerked, enough slack being allowed to let the rag at the other end hang down. If the unwanted birds appear on or too close to the bird house, the cord is given a sharp pull which will cause the rag to jerk upward and frighten the intruder away. Repeat as often as occasion requires.
Care should be taken to work the bouncer when only the undesired birds are within effective distance. However, should the contending birds actually come to bodily grips on or beside the nesting site, the fight may be broken up by vigorous operation of the alarm. The author found that this device, exercised as occasion required, in two days ended a week-old continuous struggle between a Bluebird and a pair of Tree Swallows in which the Bluebird had entirely defeated the daily efforts of the Swallows to start a nest. The Swallows were left in possession, quickly built their nest, and duly raised their brood.
Obviously, this device and procedure may be applied against Starlings, English Sparrows, or other birds, regardless of species, which for any reason one desires to discourage from building in a given bird house or other nesting-site.
The use of a rag or similar object, instead of a bell or other noisemaker, is advised because the range of alarm is thereby limited to the immediate location of the bird house, so that the desired tenants will not be frightened by the operation of the alarm when they are within hearing.