March 2023 - 9

NEWS
The Wyoming Game and Fish Department and University of Wyoming partnered this winter to learn more about bighorn sheep herds in the state. (Photo by Mark Gocke/WGFD)
Managers see surprising results
in bighorn sheep research
PINEDALE - This winter the Wyoming
Game and Fish Department, in cooperation
with University of Wyoming wildlife
researchers, captured bighorn sheep in the
upper Green River drainage north of Pinedale
to assess the animals' body condition and
overall performance for this segment of the
Whiskey Mountain herd.
This is part of ongoing research looking
at three separate bighorn sheep herds
in Wyoming: the Upper Shoshone herd in
the Absaroka Range near Cody, the Whiskey
Mountain herd in the Wind River
Range between Dubois and Pinedale and
the Jackson herd in the Gros Ventre Range
near Jackson.
Like many bighorn sheep herds across the
West, these herds have struggled with pneumonia.
However, not all sheep herds with
pneumonia have responded the same. Some
experience a slow decline, some experience
crash-recovery cycles and others show little
decline. This research seeks to understand why
herds respond differently, and researchers
have already found some indication of why
from within the same herd.
The Whiskey Mountain herd, once among
the largest populations of Rocky Mountain
bighorn sheep, has been in steady decline
since the early 1990s, primarily due to pneumonia.
The herd spans both sides of the
Continental Divide in the northern Wind
River Range. Although these sheep occupy
the same general region, researchers from the
University of Wyoming have found distinct
differences between the sheep on the Dubois
side and those on the Pinedale side.
Sheep on the Dubois side move seasonally
between high-elevation summer range
and low-elevation winter range. These are
common big game seasonal movements and
typically these populations perform well. But
habitat assessments show these sheep have
relatively poor summer forage, generally have
to travel longer distances to get their calories
and consistently have poor body condition
when captured, which has led to poor lamb
survival.
However, the sheep on the Pinedale side
stay at high elevations year-round, have better
summer forage, are some of the fattest
sheep researchers have monitored and have
better lamb survival. Lambs that were captured
in the Upper Green this winter had 11
percent body fat, which is impressive. Some of
these ewes that spend all year in the high peaks
are fatter, even after raising a lamb, than sheep
from the Dubois side that lost their lamb.
As of now, life for bighorn sheep in the
Upper Green is looking good when compared
to their counterparts on the other side
of the hill. This research provides Game and
Fish managers more detailed information
than they've ever had, which will lead to
better management decisions for the sheep.
- Mark Gocke, WGFD
Wyoming Wildlife | 9

March 2023

Table of Contents for the Digital Edition of March 2023