Determination of pesticide aerial drift and associated effects to the endangered Wyoming toad (Bufo baxteri) at Mortenson and Hutton National Wildlife Refuges and potential reintroduction sites

Metadata Updated: December 11, 2019

The endangered Wyoming toad is confined to Mortenson National Wildlife Refuge (NWR) in southeast Wyoming. Reasons for the decline of the toad are unknown, but it is suspected that pesticide aerial drift from mosquito control activities on lands adjacent to the refuge may be partly responsible. We used pesticide indicator strips and spray cards to determine the extent of malathion entering Mortenson NWR and potential reintroduction sites. Spray cards from three sampling sites had detectable malathion concentrations (0.298 - 28.8 µg/g). To determine exposure of the Wyoming toad to malathion aerial drift, we used percent survival and measured acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity in blood and brain samples of caged surrogate Woodhouse's toads. Survival was 100% and mean AChE and BChE activity in brain and plasma did not differ significantly among sampling sites. Righting trials were conducted on surrogates before and after spraying to determine if predatory avoidance behavior was affected. There was no significant difference (p <0.05) among sites. We did abundance estimates on terrestrial and aquatic insects prior to and after the spray event to determine if the toads' food source was affected. Terrestrial invertebrate abundance results were inconclusive. Aquatic invertebrate abundance was not significantly different (p <0.05) before and after spraying at any sites except the reference site and Meeboer Lake. No malathion residues were detected in the aquatic invertebrates. Our results indicate that, although some drift of malathion is occurring, the toads were not exposed to concentrations great enough to reduce adult survival, affect predator avoidance behavior, or reduce their food source. The data also provide needed information on ChE activities in amphibians.

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Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Created Date May 1, 2019
Metadata Updated Date December 11, 2019

Metadata Source

Harvested from DOI CKAN Harvest Source

Additional Metadata

Resource Type Dataset
Metadata Created Date May 1, 2019
Metadata Updated Date December 11, 2019
Publisher Fish and Wildlife Service
Unique Identifier FWS_ServCat_23120
Brent Frakes
Maintainer Email
Public Access Level public
Bureau Code 010:18
Metadata Context
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Harvest Source Id 34ce571b-cb98-4e0b-979f-30f9ecc452c5
Harvest Source Title DOI CKAN Harvest Source
Data First Published 2003-01-01
Homepage URL
Data Last Modified 2003-01-01
Program Code 010:094, 010:028
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Source Datajson Identifier true
Source Hash 05c4662382f9f02737888179407481abaa245181
Source Schema Version 1.1
Spatial -105.8653,41.16101,-105.6982,41.21926
Category "Unpublished Report"

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