Invasive and nonnative animals in Wyoming
Last checked November 3, 2026 against official sources.
On this page
9 nonnative animals are named on 3 official lists for Wyoming: “AIS Threats” (Wyoming Game and Fish Department), “Atlas of Birds, Mammals, Amphibians, and Reptiles in Wyoming” (Wyoming Game and Fish Department, Nongame Section) and “Reptiles in Wyoming (species list)” (Wyoming Game and Fish Department).
To report a sighting, see how to report.
Being on a list of nonnative species does not always mean an animal is harmful or established: each list below is described in its source's terms. A sighting of a listed animal is still worth reporting to the agency.
AIS Threats
Wyoming Game and Fish Department, no page date shown. 4 animals.
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Asian clam
Glendo and Guernsey reservoirs, North Platte River below Glendo, Fort Laramie canal, Laramie River below Grayrocks, Keyhole Reservoir, Horse Creek Wyoming Game and Fish Department
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Brook stickleback
Several drainages incl. Big Horn Lake, Glendo, Laramie, North Platte, Pathfinder-Seminoe, Shoshone Wyoming Game and Fish Department
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New Zealand mudsnail
Yellowstone National Park, Lake Cameahwait, Boysen Reservoir, Alsop Lake, Flaming Gorge Reservoir; Bighorn, Shoshone, North Platte, Salt and Snake rivers Wyoming Game and Fish Department
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Photo: Peterwchen · CC BY-SA 4.0 · Wikimedia Commons · resized Rusty crayfish
Laramie River below Wheatland Reservoir #2 to Tunnel Road; Bluegrass and Wagonhound creeks Wyoming Game and Fish Department
Atlas of Birds, Mammals, Amphibians, and Reptiles in Wyoming
Wyoming Game and Fish Department, Nongame Section, December 2021. 4 animals.
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Photo: Paul Danese · CC BY-SA 4.0 · Wikimedia Commons · resized American Bullfrog Lithobates catesbeianus
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Photo: Laura Liedtke · CC BY 4.0 · iNaturalist Eurasian Collared-Dove Streptopelia decaocto
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Photo: Surly Aardvark · CC0 1.0 · iNaturalist European Starling Sturnus vulgaris
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Photo: Sandy Wolkenberg · CC BY 4.0 · iNaturalist House Sparrow Passer domesticus
Reptiles in Wyoming (species list)
Wyoming Game and Fish Department, Last modified on 01-22-2023. 1 animal.
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Photo: ncb1221 · CC BY 4.0 · iNaturalist Red-eared Slider Trachemys scripta elegans
How to report a sighting in Wyoming
Report mountain lion sightings to Wyoming Game and Fish at 1-877-WGFD-TIP (or the non-emergency police line). Rare or interesting nongame birds, mammals, amphibians and reptiles can be reported to the WGFD Nongame Section through its "Report an Observation" form. Wyoming Game and Fish Department
Do not try to catch or handle the animal. A photo taken from a safe distance, the place and the date help the agency.
Sources
- AIS Threats. Wyoming Game and Fish Department. no page date shown; checked November 3, 2026.
Quoted passages (4)
“In Wyoming they are present in Glendo and Guernsey Reservoirs and the North Platte River downstream of Glendo Reservoir, the Fort Laramie irrigation canal, the Laramie River below Grayrocks Reservoir, Keyhole Reservoir and Horse Creek.”
“Brook stickleback have been introduced to many Wyoming waters.”
“They are present in Wyoming in Yellowstone National Park, Lake Cameahwait, Boysen Reservoir, Alsop Lake, Flaming Gorge Reservoir and in the Bighorn, Shoshone, North Platte, Salt and Snake rivers.”
“Distribution - Found in Laramie River below Wheatland Reservoir #2 to Tunnel Road, Bluegrass and Wagonhound Creeks in Wyoming.”
- Atlas of Birds, Mammals, Amphibians, and Reptiles in Wyoming. Wyoming Game and Fish Department, Nongame Section. December 2021; checked November 3, 2026.
Quoted passages (3)
“Non-native in WY.”
“Not native to North America; brought from other continents for the pet trade; released in the wild in 1974.”
“Non-native species brought into the U.”
- Reptiles in Wyoming (species list). Wyoming Game and Fish Department. Last modified on 01-22-2023; checked November 3, 2026.
Quoted passages (1)
“Red-eared Slider Trachemys scripta elegans No Nonnative No”
- Mountain Lions in Wyoming. Wyoming Game and Fish Department. no page date shown; checked November 3, 2026.
Quoted passages (1)
“Please report sightings to Game and Fish at 1-877-WGFD-TIP or the non-emergency Police Department phone.”