Small mammal shooting as a conduit for lead exposure in avian scavengers

Environmental Science and Technology
By: , and 



Lead (Pb) exposure is a widespread wildlife conservation threat. Although commonly associated with Pb-based ammunition from big-game hunting, small mammals (e.g., ground squirrels) shot for recreational or pest-management purposes represent a potentially important Pb vector in agricultural regions. We measured the responses of avian scavengers to pest-shooting events and examined their Pb exposure through consumption of shot mammals. There were 3.4-fold more avian scavengers at shooting fields relative to those at fields with no recent shooting, and avian scavengers spent 1.8-fold more time feeding after recent shooting events. We isotopically labeled shot ground squirrels in the field with an enriched 15N isotope tracer; 6% of avian scavengers sampled within a 39 km radius reflected this tracer in their blood. However, 33% of the avian scavengers within the average foraging dispersal distance of nests (0.6−3.7 km) were labeled, demonstrating the importance of these shooting fields as a source of food for birds nesting in close proximity. Additionally, Pb concentrations in 48% of avian scavengers exceeded subclinical poisoning benchmarks for sensitive species (0.03−0.20 μg/g w/w), and those birds exhibited reduced δ-aminolevulinic acid dehydratase activity, indicating a biochemical effect of Pb. The use of shooting to manage small mammal pests is a common practice globally. Efforts that can reduce the use of Pb-based ammunition may lessen the negative physiological effects of Pb exposure on avian scavengers.

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Publication type Article
Publication Subtype Journal Article
Title Small mammal shooting as a conduit for lead exposure in avian scavengers
Series title Environmental Science and Technology
DOI 10.1021/acs.est.1c01041
Volume 55
Issue 18
Year Published 2021
Language English
Publisher American Chemical Society
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description 9 p.
First page 12272
Last page 12280
Country United States
State Oregon
County Lake County, Malheur County
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