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Avian consumption of blank pesticide granules applied at planting to Iowa cornfields
Author(s) -
Fischer David L.,
Best Louis B.
Publication year - 1995
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620140913
Subject(s) - gizzard , granule (geology) , zoology , pesticide , biology , sparrow , toxicology , ecology , paleontology
Consumption of pesticide granules by free‐ranging birds was quantified by applying blank (untreated silica granules to Iowa cornfields at rates varying from 3.9 to 17.3 kg/ha and examining the gizzards of birds collected from these fields for the presence of granules. One or more granules were found in the gizzards of 39% of 256 birds collected. Counts of gizzard granules averaged 0.6 to 0.9 for the three avian groups collected (horned larks, blackbirds, and sparrows). More than 95% of the specimens contained ≤3 granules; the maximum count was 6. On the basis of granule voiding experiments, we estimate that gizzard examinations detected 24% of the granules consumed per day. Median daily consumption for birds in general was estimated to be 2.4 granules, with 95% of individuals estimated to consume ≤18 granules. For the species with the highest consumption rate, the savannah sparrow ( Passerculus sandwichensis ), median consumption was 11 granules per day, with 95% of individuals estimated to consume ≤23 granules per day. Granule availability on the soil surface was highly correlated with the application rate. Counts within the application band immediately after application averaged 15 granules/ft 2 for every 1 kg/ha applied, or about 6% of the granules applied. Our results suggest that when granular pesticides are applied to cropland, many birds may ingest granules, but the numbers ingested will generally be low.