Monday, April 4, 2011

The Short 'n Sweet Research Proposal

This is the short and sweet version of my research proposal.  I cannot believe that my first trip down there to locate study areas will be next month!  I still have so much to do...  take the truck in to a mechanic, buy a canopy (to sleep under in the back of my truck), install the CB, pick up a spare tire, check the brakes....yikes!

If you have any interest in the full document, let me know and I can email it to you.  Would love to have as many eyes on this as possible.  The same people have been editing it for three months now and I think they've gotten tired of reading it!  (So don't be afraid to point out mistakes, or anything that doesn't make sense, etc).

Effects of feral horse grazing on greater sage-grouse nesting habitat in southeastern, Oregon

Grass height and shrubs, especially sage-brush, are important to the greater sage-grouse habitat.  Grazing is hypothesized to impact sage-grouse populations by reducing the height of herbaceous cover. This would have an impact on important sage-grouse breeding sites and the successfulness of their nests.  This proposed research will test this hypothesis.  Using exclosures and vegetation canopy surveys, this study will determine the amount of herbivory by horses on sage-grouse leks in southeastern, Oregon on the Riddle Mountain Herd Management Area.  It will be concluded how much impact horse grazing has on sage-grouse nesting habitat.

The height of grasses and other vegetative cover is an important component of greater sage-grouse nesting sites (Gregg et al., 1994, Connelly et al., 1991).  Therefore, grazing by free-roaming horses may have a direct effect on this native species if vegetation is clipped too short.  This thesis will address issues pertaining to the impacts of horse grazing and how they affect the height of grasses in sage-grouse nesting habitat within the shrub-steppe biome.  It will provide needed research to maintain healthy horse populations as well as healthy populations of sage-grouse and habitat.

This study will benefit the BLM in Oregon by providing needed field research on the sage-grouse habitat located in the Riddle Mountain herd management area (HMA).  Here, the appropriate management level (AML) for this 28,000 acre HMA, determined by the BLM based on forage availability, is 33-56 horses (BLM, 2011.). As of my last conversation with the Burns District Rangeland Specialist, William Andersen, there were about 50 head of excess horses in the Riddle Mountain HMA (Andersen, Personal Communication, December 28, 2010, BLM, 2011).  According to the recent Oregon Fish and Wildlife draft plan to maintain and enhance sage-grouse habitat, federal agencies are strongly encouraged to prioritize round-ups in horse areas that are both above AML and include known populations of sage-grouse (Hagen, Anthony, & Oregon 2010). 

There are many disputes and controversies surrounding wild horses, which make management difficult.  Free-roaming horses, on the range year round, are managed as neither livestock nor wildlife as per the protections given them in the Wild Free Horses and Burros Act of 1971.  They are controlled by no one except periodic roundups facilitated by the BLM every few years to reduce populations. This method makes it impossible to control the timing and intensity of their grazing in any given location.  As inhabitants of public ranges year round, horses have the potential to have adverse effects on sage-grouse nesting habitat.   Therefore, data concerning grazing effects of free-roaming horses is needed to determine what affect they have to grass height that sage-grouse hens need for nests.  Since this area is also grazed by 552 head of cattle June through September, sites for monitoring grass height in sage-grouse nesting areas will be selected in areas where there is primary horse use in order to minimize grazing impacts by cattle.

The objective of this thesis is to provide data that will help to determine if horses have a measurable impact on perennial grasses that sage-grouse hens require for nests.  Exclosures that prevent grazing will be constructed to determine an impact to the habitat and grass height. The results of this study will  provide data to compare the impacts of horses on perennial grass screening cover so that management can be adjusted to prevent detrimental utilization of sage-grouse nesting sites in the Riddle Mountain area.  Seventy-six percent of this horse management area is sage-grouse habitat and there are eight leks located within its boundaries.  This study will add to the collection of data gathered concerning the impact of free-roaming horses on public lands (Beever, Tausch, &Thogmartin 2008, Beever, Tausch, & Brussard, 2003).  It will further the relative little consideration given to understanding the effects of free-roaming horses on sagebrush ecosystems and sagebrush obligate species (Beever and Aldridge, in press). Also, it will provide data to assist with management decisions regarding the preservation of the shrub-steppe habitats that are inhabited by many species, including the greater sage-grouse. 

To achieve the objectives of this thesis, impacts to perennial grass heights in sage-grouse leks and nesting habitat by horses will be assessed.  Monthly trips will be made over the summer of 2011 to sites in the Riddle Mountain HMA in May, June, July, August, and September. These research sites will be chosen based on known lek activity observed by the BLM Burns District where predominant grazing use is free-roaming horses.

In May, with the assistance of the BLM Burns District, temporary grazing exclosures will be constructed in sites where there is evidence of horse-use and known sage-grouse activity. To prevent any potential disturbance to the lek, these exclosures will be removed at the end of summer.  These exclosures will remain un-grazed through the summer months to monitor free-roaming horse grazing.  GPS points of the site as well as photographs will be taken to document visual changes made May through September.  Vegetation will be identified during the May visit.  A vegetation canopy cover and grass height survey will also be conducted both inside and outside the exclosure using three 30-meter transects.  With this method, a Robel pole will be used to assess height of vegetation every meter.  Cover will also be noted as grass, shrub, rock, or bare ground.

In the following months of June, July, August, and September these surveys will be conducted once monthly to record changes in the height of perennial grasses.  Transects will face north-south and will be chosen so that sagebrush is not so frequent along the line that it makes data gathering difficult (since this study is measuring grass height, not sagebrush).  As stated previously, vegetation height will be determined using the Robel pole technique, named for R. J. Robel who first used it, and the visual obstruction method (Robel et al., 1970).  At each measurement point, the last band seen before the pole disappears into the vegetation will mark the grass height.  Utilization measurement will also be collected.  Collection of vegetation will be obtained by clipping and weighing in May and again in September to compare utilization levels from the beginning of the study to the end.

This study will also utilize remote sensing data from MODIS to map changes in vegetation productivity through the summer.  Aerial photographs will also be analyzed to monitor sage-grouse leks and nesting areas.  These data will then be compared to data collected on the ground from May through September.  This supplementary data will provide seasonal changes in vegetation through the summer months and possibly provide further data of horse-use impacts.  It will also be used compare changes that occurred on the ground with grass height and cover and if it can be seen using remote sensing and aerial photographs.

The horses of Riddle Mountains are proposed to be gathered in September 2011 to reduce their population to appropriate management levels for the HMA.  Should this gather occur, a month following the removal of half the herd,  surveys will be conducted again to determine if there is a difference to grass heights when horses are returned to AML. 

This study will be done after sage-grouse chicks have moved from nests in herbaceous understory into sagebrush.  Therefore, the data collected will provide information for impact to grass height that may have an effect the following spring when they are nesting again.  If horses have decreased herbaceous height and cover significantly through the summer, there may not be sufficient height come March for sage-grouse to nest successfully in the Riddle Mountain HMA

This research determining the potential impacts of grazing by free-roaming horses within sage-grouse nesting habitats has significance beyond Central Washington University.  Findings will benefit agencies that manage free-roaming horses and greater sage-grouse.  It will provide data to consider in future management. It is the intent that this research will be presented at the Society of Range Management Annual Meeting in Spokane, Washington, February 2011.

Anderson, William. (2010, December 27). Personal Communication. (J. Phillips, Interviewer)
Beever, E. (2003). Management Implications of the Ecology of Free-roaming horses in semi-arid ecosystems of the Western United States. Wildlife Society Bulletin, 31 (3), 887-895.

Beever, E. A, Tausch, Robin A., & Thogmartin, Wayne E. (2008). Multi-scale responses of vegetation to removal of horse grazing grom Great Basin (USA) mountain ranges. Plant Ecology, 196, 163-184.

Beever, E. A. and Aldridge, Cameron L. (In Press.) Influences of Free-roaming equids on sagebrush ecosystems with focus on greater sage-grouse.  Studies in Avian Biology.

Beever, E. A., Tausch, Robin A., & Brussard, Peter F. (2003). Characterizing Grazing Distrubances in Semiarid ecosystems across braod scales, using diverse indices. Ecological Applications, 13 (1), 119-136.

BLM (2011). Kiger and Riddle Mountain Herd Management Areas Wild Horse Gather Environmental Assessment. Burns,  Oregon: Bureau of Land Management. Bureau of Land Management (BLM). (2011, February 25). Wild horse and Burro Quick Facts.

Connelly, J. W., Wakkinen, Wayne L., Apa, Anthony D.,  & Reese, Kerry P. (1991). Sage Grouse Use of Nest Sites in Southeastern Idaho. The Journal of Wildlife Management, 55 (3), 521-524.

Doherty, Kevin E., Naugle, David E., Walker, Brett L. (2010). Greater Sage-Grouse Nesting Habitat: The Importance of Managing at Multiple Scales. Journal of Wildlife Management, (74)7. 1544-1553.

Gregg, Michael. A., Crawford, John A., Drut, Martin S., & DeLong, Anita K. (1994). Vegetation Cover and Predation of Sage Grouse Nests in Oregon. The Journal of Wildlife Management, 58 (1), 162-166

Robel, R. J., Briggs, J. N., Dayton, A. D., & Hulbert, L. C. (1970). Relationships between Visual Obstruction Measurements and Weight of Grassland Vegetation. Journal of Range Management, (23)4. 295-297.


  1. Looking forward to your findings, Jessi! When we were on Warm Springs HMA, I was amazed at the height of the sage there; much of it over 6' high. But on South Steens it's tiny stuff, rarely reaching your waist.

  2. Wow! That's pretty cool! I love sagebrush. I could smell it all day long (hence the reason for Saige's name). I know the sagebrush on the Yakama Res was looking pretty sad last time I drove through and of course there's no grass height to speak of. Horses are nibbling all vegetation down to the ground. It's no wonder that between overgrazing and agriculture, sage-grouse are threatened here in Washington.

  3. I don't know if it would be helpful or not...but on the road to the Kiger viewing area on the Kiger HMA there is a pretty large pasture that is fenced. When we were there last fall nothing had been in it for some time except one unshod horse. There was lots of small bunch grass and one large bunchgrass taller than my head. Its just past the cattle guard. Hope it is of some help to you.

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