Wildlife Damage Management, Internet Center for
Date of this Version
November 1979
Abstract
Although national losses are unknown, bird damage is a chronic problem for many Filipino rice farmers and is sometimes a severe problem within localized areas. Three species of Philippine weavers (Lonchura malacca, L. leucogaster, and L. punctulata) are common pests; and other birds such as sparrows, parrots, and even ducks contribute to crop losses. Post seedling damage by Philippine weavers, the focus of this study, usually occurs from the milky to the early maturing stages of rice growth. At this time, the birds arrive in flocks, alight within the fields, and squeeze "milk" from the developing seeds or hull the doughy grains directly from panicles (Benigno et al., 1975). Although some studies (Manuel, 1930, 1934; Alviola et al. 1973; Benigno et al., 1975) have been conducted on the biology, feeding habits, and damage of Philippine weavers, little attention has been given to methods for reducing crop losses. Farmers in most countries employ combinations of favorite devices and methods in attempts to frighten birds from their fields and to reduce crop losses. In the Philippines, such combinations usually include; (1) "bird boys" who make noises to frighten the birds; (2) networks of strings, tin cans, and stones that are stretched over the fields and that rattle with the wind or when a cord is pulled; (3) "scarecrows"; (4) white flags flown several meters above the fields; and (5) wooden or bamboo, wind-driven propellers. In countries where farming practices are more mechanized, such devices are supplemented or replaced by firecrackers, exploders, or other noisemaking devices; nets to protect crops of high value; and chemical repellents. Two repellents, methiocarb (which causes conditioned food aversion; Rogers, 1974) and 4-aminopyridine (a frightening agent; De Grazio et al., 1972), have received limited study in the Philippines but appear too costly for practical use in maturing rice at this time. In the present study, we considered the possibility of using perches coated with glue to frighten birds from a farmer's field. This method would take advantage of the Philippine weaver's habit of alighting on tall weeds (e.g., Echinocloa sp.) or other vegetation within the field to feed on rice. If a few of the birds adhered to the perches, we hypothesized that the "glued" birds would emit distress calls and that the remaining birds would learn to avoid the treated fields. Such a treatment would be somewhat analogous to the repellent effect of 4-aminopyridine but could be contrived by Filipino farmers using inexpensive, local materials.