Finding of No Significant Impact

Cattle Fever Tick Eradication Program Use of Ivermectin Corn

Environmental Assessment

January 2017

In November 2016, the U.S. Department of Agriculture (USDA), Animal and Plant Health 

Inspection Service (APHIS) prepared an environmental assessment (EA) analyzing the potential 

environmental consequences of treating white-tailed deer with ivermectin to control tick vectors 

of cattle fever in Cameron, Hidalgo, Jim Wells, Kinney, Maverick, Starr, Val Verde, Webb, 

Willacy, and Zapata counties in South Texas. The EA that analyzed the potential impacts of this 

program is incorporated by reference in this document and is available on the APHIS Veterinary 

Services Tick Disease Information website or from:

USDA-APHIS-Veterinary Services

Cattle Fever Tick Eradication Program

2150 Centre Avenue

Fort Collins, CO 80526

The November 2016 EA analyzed the alternatives of (1) continuing the current cattle fever tick 

eradication efforts in South Texas with no additional efforts to minimize the spread of ticks by 

white-tailed deer (no action), and (2) strategically placing ivermectin-treated corn in feeders on 

private and public lands in Cameron, Hidalgo, Jim Wells, Kinney, Maverick, Starr, Val Verde, 

Webb, Willacy, and Zapata counties (preferred alternative). On November 30, 2016, APHIS and 

the Texas Animal Health Commission confirmed the presence of cattle fever ticks in Live Oak 

County. As a result of this confirmation, APHIS is also proposing to place ivermectin-treated 

corn in Live Oak County. APHIS reviewed the proposal and determined that it does not raise any 

additional concerns that were not analyzed in the November 2016 EA.

APHIS completed consultation with the U.S. Fish and Wildlife Service (FWS), which concurred 

on effects determinations for listed species that could occur in proximity to ivermectin-treated 

corn feeders. APHIS determined that with the implementation of mitigation measures for some 

species, the proposed action may affect, but is not likely to affect the black-capped vireo (Vireo 

atricapilla), golden-cheeked warbler (Setophaga chrysoparia), Devils River minnow (Dionda 

diaboli) and its critical habitat, ashy dogweed (Thymophylla tephroleuca), black lace cactus 

(Echinocereus rechenbachii var. albertii), least tern (Sternula antillarum), South Texas ambrosia 

(Ambrosia cheiranthifolia), star cactus (Astrophytum asterias), Texas ayenia (Ayenia limitaris), 

Texas snowbells (Styrax platanifolius subsp. texanus), Tobusch fishhook cactus (Sclerocactus 

brevihamatus subsp. tobuschii), Walker’s manioc (Manihot walkerae), and Zapata bladderpod 

(Lesquerella thamnophila).

APHIS also determined that the proposed action may affect, and is likely to adversely affect, the 

Gulf Coast jaguarondi (Puma yagouaroundi cacomitli), ocelot (Leopardus pardalis), northern 

aplomado falcon (Falco femoralis septentrionalis), and whooping crane (Grus americana). FWS 

issued a biological opinion in January 2017 indicating that the proposed use of ivermectintreated corn in feeding stations will not likely jeopardize the continued existence of these 

species. FWS included terms and conditions in the biological opinion outlining APHIS’