2017 Nutria Incident

A large, semi-aquatic rodent, native to South America, nutria (Myocastor coypus) were introduced to the U.S. (Elizabeth Lake, California) for their mink-like fur in 1899. Though the initial population failed to reproduce, subsequent introductions were successful, as records indicate nutria were successfully farmed (with escapes) in the Central Valley, North Central, North Bay, and South Coast regions of California in the 1940s-60s. Once the fur market collapsed, many nutria were released, but they were declared eradicated from the state by 1978.

Incident Timeline

March 30, 2017 - While trapping for beaver at the Hollister Duck Club (SE of Gustine, Merced Co.), Mike Enos, USDA-APHIS Wildlife Services, incidentally captures one adult nutria within a suitcase trap. The animal is identified as nutria based on the partially-webbed hind feet; orange, beaver-like teeth; rat-like tail, approximate 20 lb. size, and the characteristic white whiskers. Communication is initiated among CDFW (R4), CDFW's Wildlife Investigations Lab, USDA Wildlife Services, CDFW Invasive Species Program, CDFA Vertebrate Pest Program, and Merced County Ag Commissioner's Office.

April 27, 2017 - Initial coordination meeting is held at San Luis National Wildlife Refuge. In attendance were representatives from CDFA, Merced County Ag Commissioner's Office, Wildlife Services, Grasslands Water District, CDFW (R4), USFWS, and Tim Poale, private duck club biologist (Hollister, or other?)

May 9, 2017 - Deanna Clifford, CDFW Wildlife Investigations Lab reports results of the nutria necropsy. The animal is an adult, pregnant female, weighing 6.2 kg (13.7 lbs), with 7 fetuses present within the R uterine horn, each fetus roughly 6 cm crown to rump length, with limbs, tail, and features fairly developed. The animal was in good body condition with adequate fat reserves. The carcass was subsequently transferred to Andy Englis at the UC-Davis Museum of Wildlife and Fish Biology.

May 31, 2017 - CDFW Invasive Species Program assumes lead role in coordinating response and convenes Interagency Coordination Meeting at the Stanislaus County Agricultural Commissioner's Office facilities.

May 31, 2017 - G. Gerstenberg, CDFW, finds images of at least 2 nutria from one camera station placed on a run at Hollister Duck Club.

June 13, 14, 15, 16, 2017 - G. Gerstenberg and M. Enos trap and remove one juvenile, one adult male, one adult male, and one adult male nutria, respectively. Greg notes a decline in signs of recent activity.

June 21, 2017 - Cristen Langner, CDFW, captures images of 2 nutria near traps at Lone Tree Gun Club or Gustine Gun Club (which site?).

June 30, 2017 - G. Gerstenberg captures one, juvenile male (8.1 lbs) nutria and observes one swimming in the water nearby. Greg notes that sweet potatoes seem to be an effective bait, and reports that 3 additional traps went off with no captures, while 2 additional traps had chewing on the sweet potatoes without the traps closing.

July 5, 2017 - G. Gerstenberg captures one, adult male (15.8 lbs) nutria.

Unconfirmed Reports

May 16, 2017 - Mike Enos, Wildlife Services, received report of possible nutria sighting near Delhi, east of Hwy 99. The sighting was at a State Park on the Merced River (presumably McConnell State Park) and believed to have occurred over the weekend of May 13-14. Mike received 2nd-3rd hand information, but the sighting was reported by a State Parks Ranger, who observed one, large, nutria-like animal with 2-3 young and noted white whiskers and muzzle. The sighting was initially reported to a local CDFW biologist (unknown; not C. Langner).

May 24, 2017 - D. Kratville reports there may have been another sighting near the West Bear Creek Unit of San Luis NWR.

July 5, 2017 - G. Gerstenberg reports the caretaker from the East Gustine Gun Club stated he saw one 2 summers ago (2015) on Los Banos Creek.

Surveys and Observations

April xx, 2017 - Greg Gerstenberg, CDFW (R4), initiated camera surveys on CDFW lands.

May 11, 2017 - Brian Popper and Mike Enos, Wildlife Services, met with Lisa Selner, also USDA-APHIS and formerly with the Chesapeake Bay Nutria Eradication Project, to explore the capture site and vicinity. Old nutria tracks, characteristic tail drag marks, and an "eat out" were observed appr. 1/2 mile east of the original capture site.

May 18 (?), 2017 - David Kratville conducted camera trapping along the Merced River, including one station at the unconfirmed sighting within McConnell State Park.

May 25, 2017 - D. Kratville visually surveys the McConnell State Park ponds where the nutria were previously reported. The ponds were dried and contained old tracks that could not definitely be attributed to raccoon vs. nutria: