STP680

    Procedure for Visually Estimating Bird Damage to Grapes

    Published: Jun 1979


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    Abstract

    Bird damage was assessed in 48 plots of wine grapes located in two regions of California during 1977. In each plot, five randomly selected grape bunches on each of 40 randomly selected vines were visually assessed, using an eight-value rating scale based on the arc-sine transformation. A hoop sampler and a rope device aided random selection of the bunches in untrellised and trellised vineyards, respectively. The mean damage ratings, calculated for use in analysis of variance, were backtransformed to estimate the percentage loss in the plots. Independent observers using this system were reasonably accurate in estimating known levels of bird damage. Because of the relative variation among the plots between the among-vine and the within-vine variances, the optimum plot sampling rates for the number of vines and bunches per vine varied greatly. The procedure tested is probably most useful for comparing bird damage levels on experimental plots of grapes, but could be adapted for estimating percentage bird losses in vineyards.

    Keywords:

    vertebrate pest control, bird control, bird repellents, repellent efficacy, bird damage assessment


    Author Information:

    DeHaven, RW
    Wildlife biologists, U.S. Fish and Wildlife Service, Denver Wildlife Research Center Field Station, Davis, Calif

    Hothem, RL
    Wildlife biologists, U.S. Fish and Wildlife Service, Denver Wildlife Research Center Field Station, Davis, Calif


    Paper ID: STP34974S

    Committee/Subcommittee: E35.17

    DOI: 10.1520/STP34974S


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