Laura A. Tyson

Repellency of methyl anthranilate to pre-exposed and naive Canada geese

To improve our understanding of the effectiveness of avian feeding repellents, we evaluated whether Canada geese (Branta canadensis) exhibited learned avoidance of ReJeX-iT AG-36 (AG-36), a methyl anthranilate (MA) formulation containing 14.5% MA (vol/vol). During 2 experiments in August-September 1995, we pre-exposed geese orally to 0.0, 1.3, or 4.0 g AG-36 and released them onto 10- x 10-m grass plots treated with AG-36 at rates of 22.6 and 67.8 kg/ha. Mean numbers of bill contacts and mean numbers of geese observed on control and treated plots were similar (P ≥ 0.21) for geese pre-exposed or naive to AG-36. Overall, mean numbers of bill contacts and mean numbers of geese also were similar (P ≥ 0.56) on control and treated plots. Mean mass of droppings on control and treated plots was similar (P > 0.99) during the experiment with 22.6 kg/ha AG-36 but was greater (P = 0.01) on control plots during the experiment with 67.8 kg/ha AG-36. We conclude that learned avoidance of AG-36 by Canada geese pre-exposed orally to 1.3 or 4.6 g AG-36 did not occur and that AG-36 applied to turf in enclosures at rates of 22.6 and 67.8 kg/ha was not effective as a grazing repellent for geese.

Lethal Control of Piscivorous Birds at Aquaculture Facilities in the Northeast United States: Effects on Populations

Abstract Predation by piscivorous birds is considered a substantial threat to the aquaculture industry. However, lethal control of birds at aquaculture facilities has raised concerns about the effects on the distribution and abundance of populations of the species killed. We examined the relationship between numbers of piscivorous birds reported killed under U.S. Fish and Wildlife Service (USFWS) permits at aquaculture facilities in New York, New Jersey, and Pennsylvania and species population trends within the respective states. The USFWS issued 26 permits to 9 facilities from 1985 through September 1997. Eight species appeared on permits, but only six species were reported killed: Black-crowned night-herons Nycticorax nycticorax, double-crested cormorants Phalacrocorax auritus, great blue herons Ardea herodias, herring gulls Larus argentatus, ring-billed gulls L. delawarensis, and mallards Anas platyrhynchos. Over 13 years, the authorized number of birds to be killed per species or group (e.g., gulls) r...

Evaluation of lime as an avian feeding repellent

We evaluated the effectiveness of dolomitic hydrated lime as a feeding deterrent to captive brownheaded cowbirds (Molothrus ater) and Canada geese (Branta canadensis) during July-September 1995. We conducted 1- and 2-choice tests using grains with caged cowbirds and geese, and applications of lime to turf in dry and slurry form for geese. Lime mixed with millet or whole-kernel corn at 25, 12.5, and 6.25% (g/g) reduced cowbird and goose feeding in 4 day, 2-choice (treated or untreated grain) cage trials. Reductions in total food intake occurred for both species during similar 1-choice tests with lime (25% [g/g]) and millet or corn. Body mass of cowbirds and geese increased or remained constant during 2-choice tests. In contrast, body mass declined for both species during 1-choice tests. Application of lime to enclosed 10- X 10-m-grass plots in powder or slurry form at an application rate of 544 kg/ha also reduced goose feeding on treated plots for 2-3 days. Mean numbers of geese and mean fecal mass on control and treated plots were similar during both turf experiments. No phytotoxicity of grass was observed ≥40 days posttreatment. We recommend additional studies to determine the lower limit of repellency of lime to various bird species and its utility for turf and crop damage reduction.

Comparison of d-pulegone and mangone as cowbird feeding repellents

We compared the effectiveness of d-pulegone and mangone as feeding repellents to captive adultmale brown-headed cowbirds ( Molothrus ater Boddaert) during October- November 1995. For each repellent, we conducted 4-day, one- and two-choice cage tests using concentrations (w/w) of 0.1%, 0.10%, and 0.001% with millet. During one- and two-choice tests, 0.1% d -pulegone reduced ( P 0.05) among one-choice tests and similar to total food consumption observed during two-choice tests. We conclude that mangone is less effective than d -pulegone and would be likely to be ineffective as a repellent for seed treatment. We recommend field tests to further assess the effectiveness of d-pulegone or comparable isomers as avian feeding repellents.