WGFD and Public Discuss Sublette Antelope Migration Corridor

WGFD and Public Discuss Sublette Antelope Migration Corridor

Wyoming Game and Fish employees discuss the Sublette Antelope Migration Corridor with the public Wednesday night in Green River. SweetwaterNOW photo

GREEN RIVER — The Wyoming Game and Fish Department (WFGD) and residents discussed the effort for the identification and designation of a Sublette antelope migration corridor Wednesday night in Green River.

Each fall, the Sublette antelope herd migrates south from summer ranges in the foothills of the Wyoming Range, Bondurant and Jackson Hole areas to lower elevation winter ranges near Pinedale, Green River and Rock Springs. The migration path stretches 360 miles, and is considered the longest recorded antelope migration in the western U.S., and passes through lands managed by the federal and state governments, as well as privately owned lands. WGFD said that with the formal identification of the corridor, additional funding opportunities become available for conservations based projects on private and public lands.

The migration corridor has been studied for the past 20 years, from 2002 to 2022. Sean Yancey, Wildlife Management Coordinator for Green River WGFD, previously told the Sweetwater County Commissioners that they deployed 600 GPS collars on individual pronghorn in the herd, and that 415 animals were deemed to be migratory.

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“So they have a distinct summer and winter range and a path that connects those two. The rest don’t have distinct movements,” Yancey said.

The north section of the migration corridor is considered “high use” which means 20% or more of the herd uses the migration paths in that area. The central, southwest and southeast sections all have medium to low use, meaning that 10-20% use the paths in the medium use areas, and only 2 or more animals use the low use paths.

The GPS identified paths with a 300 meter buffer, and the data has revealed the important pathways, potential obstacles known as bottlenecks, and stop-over areas where antelope spend the majority of their time resting and foraging during their migration. Ultimately, WGFD has found that over 75% of the herd is migratory.

“This is one of the most data-rich herds in the world,” Yancey said during the public meeting in Green River.

Yancey said that the primary threats the herd faces are human impacts, such as suburban development, roads, fences, and presence, as well as vehicle collisions, and renewable energy, oil and gas development.

This map shows the entire Sublette Antelope Migration Corridor with the high, medium, low use areas marked, as well as stopovers. Courtesy of WGFD

Public Comments and Concerns

John and Joy Erramouspe operate G&E Livestock between Farson and Boulder, and they expressed concerns with this migration corridor having ramifications on their private land, and on energy development in the state.

“We will not be able to graze our animals,” John said. He added that he has mineral rights on his property that he is worried about not being able to get.

Joy said that she sees antelope all over the Jonah fields, and that oil and gas do not seem to affect the animals as the herd hasn’t appeared to decrease. Yancey stated that while certain factors may not appear to be direct impacts to the herd, they can be indirect. John further claimed that several energy companies helped fund the data collection on this herd, and now WGFD is “trying to wipe them off the map”.

However, WFGD said that identifying and designating the corridor will not prohibit development or human activity in the high, medium or low use areas. Yancey said that the high use areas would have different stipulations than the medium and low use areas, but overall the corridor allows WGFD a seat at the table when making decisions within the migrations paths.

According to WGFD, development and use can occur in the low and medium use areas, but minimization should be considered where appropriate. In the high use areas, surface disturbance and human presence shall be limited to levels that maintain the corridor functionality and do not cause migration animals to avoid or leave the high-use portion of the designated corridor during migration periods.

One resident asked if raising the bottom wire in fences helps the antelope get through fences, to which Jill Randall, Big Game Migration Coordinator, said it does. However, she said in instances such as last winter when there’s two feet of snow, the fences are still an obstacle. Yancey said that this last winter was rough on the pronghorn and deer, killing roughly half the herd, bringing the population from about 43,000 animals to around 23,000.

“There’s a heightened sense of importance on preserving some of these important routes that this herd needs,” Yancey told the Commissioners a few weeks ago.

Randall said that providing gates in the fencing is a much better solution to helping antelope migrate. Former WGFD employee Tom Christiansen noted that the issue is they can’t teach an antelope to use adjustments to fencing.

WGFD is accepting public comments until Jan. 5, 2024. Comments can be submitted online or by mail to the Pinedale Regional Game and Fish Office, PO Box 850, Pinedale, WY, 82941. Written comments will be considered prior to the Wyoming Game and Fish Commission during its tentative March 2024 meeting in Pinedale, where they will present the final threat evaluation to the commission for a decision. If designation is pursued, a risk assessment will be developed in Summer to Fall 2024 and then Governor Mark Gordon will review the executive order.