That must not be in the Yukon, where you'd have to go A LOT lower (if any)! Here in eastern WA State, I would guess they range up to about 2,800 ft around Vantage.
I have personally found them at 5,700’ and have been told that in Southern Colorado they go up to about 7,500’. My buddy who lives in the southern Sierras in Kali is overrun with them every few years at 5,200’.