WYOMING — On June 4, the University of Wyoming’s deer migration initiative shared up-to-date migration data of Mule Deer 665’s long journey from the Red Desert to her annual summer grounds near Teton Pass.
Deer 665 was born in June 2021, and Wyoming Migration Initiative (WMI) wrote via Facebook that this is her eighth migration between endpoints in the Red Desert and the Tetons on the Wyoming/Idaho border. Deer 665 utilizes the Hoback Migration Corridor, a route also used by thousands of other migrating mule deer.
According to WMI data, from December 3 until May 5, Deer 665 was in and around the town of Superior. After her spring capture on March 3, she moved about 3 miles north of Superior before returning to her usual range on March 8. Then at one point on April 5, she was less than 400 feet west of the Superior library.
WMI wrote that 665 left her winter range on May 5, about a month later than the rest of her herd. This is similar to her late starts from previous years, when she lingered in the Red Desert after many other animals had already started migrating north.
Her tracking data reveals that when she left her winter range, she moved about 13 miles north to the Killpecker Sand Dunes in 24 hours. She passed west of Steamboat Mountain, and stopped over on a ridge above Johnson Canyon on May 7 or 8. She covered about 52 miles in the first week, crossing a highway and making two stopovers.
WMI reported that on May 9, Deer 665 covered 18 miles, reaching the crossing of WY28. After negotiating the fences along the road, she made another 10-mile movement north on May 10.
“She took a rolling stopover eating springtime plants across four miles of the Prospect Mountains,” the WMI wrote. “That concluded her first week of spring migration on May 12.”
Tracking data confirms that Deer 665 began the winter at 8.3% body fat on December 7, 2024, making her one of the largest females in the herd. As of March 3, she weighed 157 pounds and carried 5.9% body fat. This level of energy reserves made her about average for the herd as of this March. Her collar data also revealed that she is pregnant.
“We are excited to report that as of March, Deer 665 is pregnant with two fawns, each with a fetal eye diameter of 15mm,” WMI wrote. “This is ahead of the 12mm for the fawns she carried in March 2024. The 2024 fawns were not with her in November of last year, which indicates she lost them somewhere between the Tetons and the Prospect mountains for unknown reasons. Hopefully 2025 will go better for Deer 665 and her fawns!”
The WMI will continue to post Deer 665’s weekly migration updates via Facebook.
“Will she continue her Prospect Mountains stopover, or set off on the migration trail again?” the WMI asked. “We’ll let you know next week.”
