Anthranilitic acid derivatives, used as common food additives, have been explored as bird repellent agents for a number of years. Research in this study show that methyl anthranilate, when exposed to the UV spectrum of sunlight, readily dissipates within 64 hours. The addition of surfactants and extenders did not appreciably alter the degradation curve, nor did they lessen the phytotoxic properties of the chemical. Field trials under IR-4 guidance and support indicate that methyl anthranilate (MA) is an effective, biodegradable, nontoxic bird repellent. In formulation with a lipid molecular binding compound, degradation of methyl anthranilate was extended from four to ten days. Phytotoxicity, at effective application rates, was eliminated. Damage to cherries was reduced 43% to 98% depending on cultivar, number of birds present, and crop loads when the treated crops were compared with untreated crops. Depredation of blueberries was reduced 65% and 99% for two varieties. Feeding on wine grapes was diminished 58% to 88%, depending on the affected vinifera. Tasters could not distinguish between treated and untreated fruit nor could certified graders find any reduction in fruit quality.

Field trials using methyl anthranilate, formulated as Bird Shield® repellent, were performed by aerial applicators at one pint per acre on sweet com in Colorado, and sunflowers in North Dakota, and at one, two, and four pints per acre on cherries in Washington. Nineteen com fields ranging in size from 9 to 25 acres were treated twice, at five day intervals, prior to harvest and compared with six untreated fields during a two year study. During the same time period ten sunflower fields, along with their adjacent cattail marshes were treated twice, at seven day intervals when the birds began to feed on the ripening seed, and compared with six untreated counterparts. Five out of the six untreated com fields were unharvestable, with greater than 75% damage, because of the severe damage caused by the resident populations of red-wing blackbirds (Agelaius phoeniceaus). Nine of the treated fields sustained no damage at all. The damage in the remainder was contained at pre-treatment levels (4% to 20%). The two applications of the repellent were sufficient to move the resident population of blackbirds out of the sunflower fields with no substantial damage to the crop. Untreated sunflowers sustained 783 to 90% damage. Treated sunflowers sustained between 2.6% to 3.4% damage. The difference in seed weights between untreated and treated plots was significant (P=0.01) with a mean weight of 0.018 g/cm2 of seed per head within the former and 0.084 g/cm2 of seed per head within the latter. Harvest weights ranged from 133 to 700 lbs/ac (mean=344) in the untreated plots while weights ranged from 1430 to 1909 lbs/ac (mean=1675) in the treated plots. No adverse effects were noted with fish or resident populations of ducks. The application of the repellent by helicopter reduced bird damage from just under 13% in one untreated cherry orchard to between 0.08% and 1.0% seven days later with 1, 2, and 4 pints/ac rates in comparable orchards. Greater differences were encountered when the repellent was applied at two additional sites. When 2 pints/ac was applied, bird damage was limited to 8% after 15 days when the untreated block sustained between 58% to 68% damage.

The use of disaccharides to discourage bird depredation to agricultural crops has elicited some interest during the last few years. Data developed in these trials indicate that several avian species are intolerant to sucrose because of the lack of sucrase enzymes in their digestive systems. Based on this research it is hypothesized that progressively increasing rates and volumes of solutions would elicit consistent adverse stress reactions. Furthermore, that if birds were intolerant to sucrose, because of their co-evolutionary development with plants, then they should Jack the ability to digest lactose. The data developed in these trials does not support either hypothesis. A maximum of 603 of the birds tested showed stress symptoms to 0.75 M sucrose (6.26 mg/Kg body wt.) and 1.00 M lactose solutions (9.15 mg/Kg body wt.) when the birds were subjected to 2 cc treatments. Less than 40% were stressed by the lower concentrations. No adverse reactions were noted with 1 cc concentrations of either solutions or rates. Treating fruit with sucrose did not appear to affect the results until 1.00 M (3.83 mg/Kg) sucrose solutions were applied. No adverse results were obtained with lactose treated fruit.

Artificial perches and nest boxes were placed in three Pacific Northwest orchards to assess their effectiveness in attracting birds of prey to reduce vole populations. The data indicated that birds could be attracted under some conditions but vole populations were not significantly affected. Additional factors such as vegetative biomass and human activity may limit their usefulness in reducing rodent populations under intensive agricultural conditions.

The physical impact of voles in agriculture and forestry has been duly noted by many researchers around the world. The economic impact of the various species, however, has not received much attention other than to note that losses from these animals can be substantial when population levels become high. This study assesses the economic impact of an extremely high population of Microtus montanus (mountain voles) in a large apple (Malus sp.) orchard in northcentral Washington State (U.S.A.) over a two-year period. In this study, 200 trees were harvested, weighed, graded, and compared by the amount of visual damage that could be seen above the soil surface. These values were then compared with cash values received by growers for the season. Production was decreased a weighted average of 36% (31% for red delicious and 53% for golden delicious) or $3036/ac. ($7500/ha.) during the first year. In the second year, production increased 3.2 fold but still did not reach that of the control orchard. If 30% of the orchards in the state were to suffer the same level of infestation, over $137 million/year could be lost because of poor management and control programs.

Three types of assessment techniques explore the possible environmental hazards of two anticoagulant compounds currently used for rodent control. In the first, rheological methodologies were used to assess the ability of pelletized baits to withstand precipitation. From these data, objective information was developed to assist agricultural producers to select a proper bait for a specific climatic period. Bioanalytical evaluations of chlorophacinone indicated that the compound decomposes when exposed to ultraviolet light into four nontoxic elements. Hence, if translocation were to occur, the elements--not the parent compound--would be the likely candidates. Finally, radioactive (14C) bromadiolone was tested for translocatability. From the preliminary data developed to the date of this report, little, if any, translocation occurs.