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Dillon Field Trip

Dillon Field Trip Notes

June 23, 2004

Anne Cossitt welcomed the group and summarized the purpose of the field trip, which was to identify seasonal sage grouse habitats and assess and discuss habitat conditions. Cossitt handed out copies of Appendix B of the state sage grouse plan which contains habitat assessment worksheets. Cossitt introduced Jim Roscoe, BLM biologist, who organized the field trip and would lead the group.

Field Trip Location

The field trip took place on lands west of Dillon on BLM lands near Dice Creek.

Stop 1: Breeding/Winter Habitat Area

Photo 1: Describing the site

Jim Roscoe briefly described the site. It has an average precipitation of approximately 15 inches per year (in average years, not necessarily recently during the drought). There is a good mix of habitats in the area, including late brood rearing along the drainages. The area of sage brush that was at the site had been part of a larger area that had been treated in the 1960s and which had re-established. Sage grouse in the area have been radio-collared and have stayed within a 5 mile range; they are not migratory. There does, however, seem to be a fair amount of movement within their range, except when they are brooding. Lek sites have also changed over time; in this particular area the birds used a lek for about 5 years, then moved to another site for about 8 years, and have since moved from that lek site.

Rick Northrup, FWP Biologist, added that winter and breeding habitat are more critical than summer-later summer habitat because sage grouse are more mobile in the summer and able to locate summer habitat.

Jim Roscoe indicated that a graduate student, Coleen Wisinki, is working with radio-collared sage grouse to track their movements and better identify their habitat needs. There were some problems with data in the past year, but hopefully there will be better data and information by next year.

Jim Hagenbarth noted that it is the juvenile mortality that seems to be driving sage grouse population. He commented that it's important to follow consistent methodology—identify the site potential for sage grouse habitat, identify management actions as needed to reach the site's potential, implement the actions, and then monitor and evaluate. He also mentioned that there is more to the site potential than just sage grouse—Brewer's sparrow and pygmy rabbit were also species of concern. (Note: a pygmy rabbit was spotted during the field tour.) He also mentioned that there may be a need to think about how to replace old, degenerate sagebrush.

Sue Marxer noted that all of the old ditches that had been built by homesteaders likely also provided some summer habitat and insects for sage grouse.

Assessing the Habitat with Tools in Appendix B of State Plan

Photo 2: Assessing the habitat

Participants then worked through the process of assessing the site's habitat conditions for breeding habitat using the protocol in Appendix B.

A tape was laid down for a line intercept. Ron Wiseman, who has been using Connolly's methodology in the field for several years (although he has not been using the forms in Appendix B), marked the areas of live sagebrush canopy cover, with a resultant 12.5% live canopy cover. Agencies noted that some use the Dobbenmire frame technique to arrive at canopy cover. For comparative purposes, the canopy cover was also calculated with the Dobbenmire frame, with a resultant 27.5% canopy cover. Jim Roscoe pointed out the need for a consistent protocol, given the disparity, and indicated potential problems with literature and data that does not clarify the methodology used to determine canopy cover.

The group noted that the forms in Appendix B are based on Connolly's methodology. Both Ron Wiseman and Jim Hagenbarth, who have been in the field with Connolly, noted that the forms may be more rigid than Connolly himself might be. Ron Wiseman pointed out that it is real important to take notes on conditions that may not be on the forms, e.g., noting the presence of insects, sage grouse droppings, etc.

Photo 3: Group considers site selection

Using the Dobbenmire frame as outlined in Appendix B, the approximate result was 85% bare ground, 10% forbs, and 5% grasses. Ron noted that he measures this year's grass and also measures residual grass as well.

The group also discussed how to select the site for measurement. There was a general concurrence that it should be within a context of the broader landscape and that there should be some analysis or consideration of that broader landscape and its potential/actual use by sage grouse.

The following is a summary of results from the assessment.

  • Cover type: Big sagebrush.
  • Average Big Sagebrush Canopy Cover: With an average canopy cover of 12.5%, the site was identified as "marginal."
  • Average Big Sagebrush Height: Average height measured within the range for " suitable" habitat.
  • Big Sagebrush Growth Form: Form was "suitable."
  • Average herbaceous grass and forb height: Between 5-7 inches: "marginal" habitat.
  • Average grass canopy cover and Average forb canopy cover. 10%--"marginal."
  • Average forb canopy cover: Less than 5%, "marginal." The group noted that the spring was not conducive to forb production that would be evident at this time of the season this year. The diversity of the forbs was relatively high, but the occurrence was low.

Overall Site Evaluation: This site would rank as generally "marginal" using the forms and protocol for habitat assessment in Appendix B. However, the group appeared to consider this site in relatively good condition, given its potential. Sue Marxer questioned the categories of "suitable," "marginal," and "unsuitable," and wondered if there might be a better way to assess.

General Observations

Many in the group talked about the need to take site specific conditions and the overall landscape for sage grouse into account in assessing the habitat.


Bob Brannon
Anne Cossitt
Craig Fager
Pat Fosse
Jim Hagenbarth
Gary Hammond
Tom Heintz
Peter Husby
Sue Marxer
Rick Northrup
Reyer Rens
Jim Roscoe
Brad Weatherd
Ron Wiseman