Evaluation of Bird Shield™ as a blackbird repellent in ripening rice and sunflower fields

Abstract

Chemical repellents sometimes can provide a nonlethal alternative for reducing wildlife impacts to agricultural production. In late summer and autumn 2002, we evaluated Bird ShieldTM (active ingredient: methyl anthranilate, Bird Shield Repellent Corporation, Spokane, Wash.) as a blackbird (Icteridae) repellent in Missouri rice fields and North Dakota sunflower fields. We selected 5 pairs of ripening rice fields in southeastern Missouri and randomly allocated treatments (treated and control) within pairs. The repellent was aerially applied by fixed‐winged aircraft at the recommended label rate and volume (1.17 L Bird Shield/ha and 46.7 L/ha, respectively); 1 field received 2X the label rate. We observed no difference in average bird activity (birds/minute) between treated and control fields over the 3‐day post‐treatment period (P = 0.503). We used reversed‐phase liquid chromatography to quantify methyl anthranilate residues in treated fields. The maximum concentration of methyl anthranilate in rice samples was 4.71 μg/g. This concentration was below reported threshold values that irritate birds. In North Dakota we selected 6 pairs of sunflower fields used by foraging blackbirds. We randomly selected 1 field from each pair for 2 aerial applications of Bird Shield at the label‐recommended rate ∼1 week apart. The remaining 6 fields served as controls. Daily bird counts, starting the first day of application and continuing for 5–7 days after the second application, showed similar numbers of blackbirds within treated and control fields (P = 0.964). We observed no difference in sunflower damage within treated and control fields (P = 0.172) prior and subsequent to the treatment. Bird Shield was not effective for repelling blackbirds from ripening rice and sunflower fields.

Food color, flavor, and conditioned avoidance among red-winged blackbirds

“…Although no effective avian repellents are presently registered for agricultural applications in the United States, nontoxic and nonlethal repellents designed to create strong food aversions, perhaps by acting specifically on the emetic system of the midbrain and brainstem [1], are needed to reduce bird damages to newly planted and ripening crops [29]. Indeed, the elucidation of color and flavor preferences, and relevant avoidance characteristics may be useful for reducing potential hazards of pesticide delivery systems for birds [30,31] and developing chemical compounds as avian repellents [28,32].…”

Spring Dispersal Patterns of Red-winged Blackbirds, <em>Agelaius phoeniceus</em>, Staging in Eastern South Dakota

“…Unfortunately, blackbirds habituate quickly to frightening agents, particularly if the crop is a preferred food in an area of limited alternate foods (Ward 1979). The taste repellent, methyl anthranilate, is also used by producers, but the concentration in the commercial product (BirdShield™) is below the known repellency threshold, despite the formulation's high cost (Werner et al 2005). Experiments with avicide were tried in sunflower fields with ongoing damage.…”

Reconciling sensory cues and varied consequences of avian repellents

“…For the purpose of protecting newly planted [12,15] and ripening crops from blackbird depredation [16][17][18][19], we recommend application(s) and the presence of flavor and/or color cues sufficiently similar to the applied, postingestive repellent throughout the period of needed crop protection. For example, anthraquinone absorbs near-ultraviolet light [20] visible to most birds [21] and it is a postingestive, cathartic purgative [8].…”