# Presentation: 549133

## THE IMPORTANCE OF FORBS FOR SAGE GROUSE: RESEARCH NEEDS AT THE LANDSCAPE SCALE. Brad Schultz, Extension Educator, University of Nevada Cooperative Extension, Winnemucca, NV 89445

**ABSTRACT**: A recent meta-analysis of sage grouse nest success found poor relationships between nest success and individual herbaceous attributes. The best predictors of nest success were total shrub cover and percent forb canopy cover. All multiple regression equations that included these two variables had statistically significant (P<0.08) relationships. For a given amount of shrub cover, an increase in forb cover resulted in higher nest success rates. Forbs are a well documented biological requirement for sage grouse, from before egg-laying through brood-rearing. Forbs occur throughout most sagebrush landscapes. Their abundance at the landscape scale, however, varies widely due to biophysical constraints in site potential and varying phases of plant succession. In addition to forb abundance, other landscape level biophysical constraints probably combine to determine the potential size of a sage grouse population. A substantial amount of previous research has largely focused on vegetation (habitat) attributes found at discrete nest sites and slightly larger nest areas (typically defined as an area around nests _<_1,200 m2). The grouse is a landscape level species; thus, land managers require knowledge about habitat constraints that influence sage grouse populations at the landscape scale. This presentation will present a theoretical outline about the probable influences of spring snow cover, ecological site potential, spatial relationships among ecological sites, phases of plant succession, and their respective influence on forb production at the landscape level. The results are expected to identify new directions for research about how vegetation and landscape influence sage grouse populations.

**INTRODUCTION: **A meta-analysis by Schultz (2004) found the very specific, numeric guidelines for herbaceous height and cover in sagebrush communities have very poor statistical relationships with nest success, and concluded they are questionable at best. The results of Schultz’s meta-analyis did find strong statistical relationships between nest success and forb cover and shrub cover. Most work about nest success has focused on the immediate vicinity of the nest (<1,200-m2), despite sage grouse being classified as a landscape species. If sage grouse are a landscape species, and forb cover is an important driver of nest success, then it is imperative that biologists and land managers understand the bio-physical processes that determine the availability and abundance of forbs at the landscape scale, from the period prior to nest initiation through early brood rearing.
-      In Nevada, copulation typically occurs from late March through early April (inferred from Schroeder et al. 1999). Nest areas are selected 1-2 weeks before copulation, incubation begins about 3 weeks after copulation, and peak hatch occurs 6-7 weeks after copulation (Mid May to late May). Forbs are an important dietary requirement for hens from pre-incubation through early brood rearing, and increase in importance for chicks as they age. Also, forbs add to plant community diversity, which may affect insect abundance and diversity. These insects are important to chicks during their first three weeks of life. This information, collectively, indicates that forb availability and abundance are important for sage grouse reproduction from about April 1 through early to mid June, when the reproductive unit is essentially stationary in space.
-      Most of central and northern Nevada has a classic Basin and Range topography. Valley bottoms vary from about 4,000 ft to over 6,000 ft elevation, and the mountain ranges have one spine that typically crests in elevation between 7,500 ft and 11,000 ft. Within this broad elevation range lies the sagebrush belt that provides  nesting and early brood rearing habitat for sage grouse. The quality of this habitat varies from poor to excellent due to reasons beyond the mere presence or absence of sagebrush. Probable influences include: snow cover at the time of nest initiation and throughout the nesting period; topography and geomorphology and their influences on both snow cover and/or the presence (or absence) of specific ecological sites; the mixture of ecological sites in the area potentially inhabited by sage grouse; the intrinsic potential of these sites to produce an abundance of forbs; and the successional state of individual ecological sites and its influence for forb production. Interactions among these factors determine the spatial area regularly available to sage grouse across years to nest and provide early brood rearing habitat.
-      Only a small part of a landscape potentially inhabited by sage grouse may ever be high quality nesting habitat. Conversely, under the right landscape conditions virtually all of an area inhabited annually may be suitable nesting and brood rearing habitat. The structure and function of a landscape, however, undoubtedly influences both the intrinsic population range possible in a management unit, and the current size of that population. Understanding landscape structure and function is essential to understanding sage grouse population size and change. This presentation provides limited data to support the fore-mentioned concepts and identifies the need for landscape scale research to improve our understanding of sage grouse population size and dynamics.

**	****	****	****	****Sample **
**	****Elevation****	****	****size****	****	****1st****	****	****3rd****	**
_**Snow course Site**_**	**_**(ft)**_**	**_**MLRA**_**	**_**(yrs)**_**	**_**Minimum**_**	**_**Quartile**_**	**_**Median**_**	**_**Quartile**_**	**_**Maximum**_
- Montgomery Pass	7100	CBM	22	  0.00	  0.00	  0.00	    1.00	  27.00
- Big Cr. Campground	6600	CNBR	60	  0.00	  0.00	  0.00	    3.00	  25.00
- Murray Summit	7250	CNBR	65	  0.00	  0.00	  0.00	  11.00	  37.00
- Kalamazoo	7400	CNBR	14	  0.00	18.00	21.00	  28.75	  53.00
- White River	7400	CNBR	36	  0.00	  0.00	  0.00	    7.50	  33.00
- Bird Creek	7500	CNBR	55	  0.00	  0.00	  6.00	  16.00	  34.00
- Big Creek Mine	7600	CNBR	58	  0.00	  2.00	  9.50	  20.00	  44.00
- Robinson Summit	7600	CNBR	55	  0.00	  0.00	  0.00	    3.00	  49.00
- Big Creek Upper	7800	CNBR	45	  2.00	12.00	22.00	  32.00	  57.00
- Baker Creek 1	7950	CNBR	60	  0.00	11.25	17.50	  28.50	  54.00
- Silver Creek	8000	CNBR	41	  0.00	  9.50	13.00	  22.00	  53.00
- Corduroy Flat	8720	CNBR	15	  0.00	  0.00	  8.00	  20.00	  50.00
- Ward Mountain	8900	CNBR	33	  1.00	36.25	52.00	  66.00	101.00
- Baker Creek 2	8950	CNBR	61	20.00	36.00	46.00	  60.00	  86.00
- Berry Creek	9100	CNBR	40	32.00	40.25	49.50	  60.25	  80.00
- Defiance Mine	9200	CNBR	23	36.00	42.00	52.00	  72.00	  96.00
- Baker Creek 3	9250	CNBR	61	22.00	42.50	54.00	  66.50	  99.00
- Galconda	6560	H	43	  0.00	  0.00	  7.00	  18.00	  40.00
- Forty-nine	6000	MHP	46	  0.00	  0.00	  5.00	  14.25	  28.00
- Little Bally Mtn	6000	MHP	39	  0.00	  0.00	  3.00	    8.00	  82.00
- Hays Canyon	6400	MHP	43	  0.00	  0.00	  0.00	  11.00	  30.00
- Disaster Peak	6500	MHP	41	  0.00	14.50	28.00	  38.50	  76.00
- Bald Mountain	6720	MHP	60	  0.00	  0.00	  4.00	  13.75	  47.00
- Tremewan Ranch 	5700	OHP	62	  0.00	  0.00	  0.00	    0.00	  17.00
- Ryan Ranch	5800	OHP	48	  0.00	  0.00	  0.00	    0.75	  20.00
- Lamance Creek	6000	OHP	44	  0.00	  5.50	20.00	  26.50	  78.00
- Taylor Canyon	6200	OHP	50	  0.00	  0.00	  3.50	  20.25	  41.00
- Quinn Ridge	6300	OHP	45	  0.00	  0.00	  0.00	    1.00	  21.00
- O'Neill Creek	6480	OHP	20	  0.00	  0.00	  6.00	  16.25	  55.00
- Dry Creek	6500	OHP	61	  0.00	  0.00	  1.00	  10.50	  45.00
- Gold Creek	6600	OHP	64	  0.00	  6.00	14.50	  20.75	  37.00
- Harrison Pass 1	6600	OHP	66	  0.00	  0.00	  5.00	  17.25	  33.00
- Columbia Basin	6650	OHP	37	  0.00	  5.00	18.00	  30.50	  60.00
- Big Bend	6700	OHP	62	  0.00	18.75	30.00	  35.25	  56.00
- Buckskin Upper	6700	OHP	47	  4.00	21.00	27.00	  35.00	  64.00
- Fry Canyon	6700	OHP	63	  0.00	10.00	18.00	  25.00	  55.00
- Laural Draw	6700	OHP	30	  0.00	17.00	22.50	  32.75	  56.00
- Martin Creek	6700	OHP	45	  0.00	17.50	23.00	  33.00	  60.00
- Fox Creek	6800	OHP	52	  8.00	22.00	30.00	  37.00	  61.00
- Jack Creek Lower	6800	OHP	67	  0.00	  0.00	  8.00	  15.00	  42.00
- Rodeo Flat	6800	OHP	58	  0.00	10.75	18.00	  24.00	  51.00
- Trout Creek Lower	6900	OHP	58	  0.00	  0.00	  7.50	  16.00	  33.00
- Fawn Creek	7000	OHP	21	  0.00	  6.50	24.00	  42.00	  84.00
- Jakes Creek	7000	OHP	18	  0.00	  0.00	14.50	  23.25	  60.00
- Merritt Mountain	7000	OHP	35	  0.00	  8.00	15.00	  22.00	  42.00
- Tent Mountain Lower	7000	OHP	24	  0.00	11.00	22.50	  36.00	  64.00
- Lamoille #1	7100	OHP	71	  1.00	21.00	26.00	  34.00	  56.00
- Seventy-Six Creek	7100	OHP	40	10.00	26.25	36.00	  42.00	  58.00
- Buckskin Lower	7200	OHP	48	  0.00	15.00	21.00	  30.00	  68.00
- Midas	7200	OHP	57	  0.00	  0.00	  1.00	    5.00	  44.00
- Jack Creek Upper	7250	OHP	49	11.00	24.00	30.00	  37.00	  67.00
- Harrison Pass 2	7400	OHP	47	  0.00	   0.00	13.00	  26.00	  45.00
- Snow Storm Mtn 	7420	OHP	18	  0.00	20.00	37.50	  45.25	  69.00
- Smith Creek	7600	OHP	26	21.00	29.75	33.50	  44.25	  78.00
- Lamoille #3	7700	OHP	54	17.00	32.50	36.50	  46.50	  65.00
- Pole Canyon	7700	OHP	27	  0.00	21.00	31.00	  45.00	  99.00
- Toe Jam	7700	OHP	36	  0.00	15.75	25.00	  39.75	  66.00
- American Beauty	7800	OHP	35	  4.00	21.00	27.00	  35.00	  75.00
- Bear Creek	7800	OHP	50	37.00	52.50	60.50	  74.00	  94.00
- Granite Peak	7800	OHP	45	18.00	31.50	37.00	  52.00	199.00
- Stag Mountain	7800	OHP	37	  0.00	  2.50	12.00	  22.50	  78.00
- Hole in the Mountain	7900	OHP	31	14.00	33.00	61.00	  75.00	108.00
- Red Point	7940	OHP	15	  0.00	18.00	37.00	  45.00	  55.00
- Green Mountain	8000	OHP	45	15.00	30.50	38.00	  45.00	  82.00
- Dorsey Basin	8100	OHP	48	14.00	31.25	41.00	  53.25	  86.00
- Pole Cr. Ranger Stn.	8330	OHP	38	38.00	49.00	61.50	  72.25	  91.00
- Tent Mountain Upper	8350	OHP	27	  0.00	53.00	62.00	  72.00	  96.00
- Jacks Peak	8420	OHP	37	42.00	59.00	75.00	  89.50	146.00
- Corral Canyon	8500	OHP	46	36.00	44.00	55.00	  63.00	  87.00
- Trout Creek Upper	8500	OHP	52	  1.00	36.25	52.00	  66.00	101.00
- Lamoille #5	8700	OHP	65	38.00	62.00	75.00	  86.50	117.00
- Goat Creek	8800	OHP	37	36.00	45.00	57.00	  66.00	  89.00
- Hummingbird Springs	8945	OHP	36	46.00	59.25	73.50	  83.50	106.00
- Robinson Lake	9200	OHP	29	14.00	64.00	80.00	105.00	155.00

**Methods**: Snow course and SNOTEL data were obtained for all sites in Nevada with sage grouse populations. The median snow depth and quartiles on April 1 were calculated for each snow course site (n=74), and similar statistics for melt-out dates for SNOTEL (n=25) sites. Vegetation data from select ecological sites from most of the Major Land Resource Areas (MLRA’s) inhabited by sage grouse was obtained to demonstrate differences in potential forb production between ecological sites and across elevation ranges. The number and type of sagebrush sites in the Humboldt, Fallon-Lovelock, and Carson Basin and Mountain MLRA’s is similar; therefore, only data from the Humboldt MLRA are presented. The topographic structure of 47 sage grouse population management units (PMU’s) was classified into one of four categories (Figures 1a-1c): 1) broad rolling mountains with most of the area below 7,500 ft elevation; 2) long, narrow, steep sided mountain ranges with crests typically above 8,000 ft; 3) plateaus and mesas largely between 5,500 and 7,000 ft elevation; and 4) combinations of one or more. The sage grouse population in each PMU was converted to a ratio of acres/bird. Broad, landscape level relationships among these variables are identified to demonstrate potential hypotheses about factors that control sage grouse populations, and which require further research.

- Figure 1a. Landform Classification 1. Elevation Range typically is 5,000 to 8,000 ft, with most areas below 7,500 ft. Mountain side slopes may be steep or shallow, but the crest is broad with level to gently rolling topography.

**Figure 1b**. Landform Classification 2. Classical Basin and Range topography. Valley bottoms vary from about 4,000 ft to over 6,000 ft elevation, with shallow sloping alluvial fans that rise to steep mountain side slopes. The spine of the mountain range may crest from about 7,000 ft to over 10,000 ft, and is narrow along it entire length.

**Figure 1a**

**Figure 1c**. Landform Classification 3. Landforms are comprised of extensive areas that resemble mesa’s or plateaus. Elevation range is typically between about 5,500 ft and 7,000 ft, with comparatively small vertical change across the landscape.

**Results and Discussion:** Snow depth from mid to late March through early June should influence the area available for nesting, and consequently early brood rearing habitat. Landscape locations with a substantial (currently undefined) snow depth at the time of nest initiation probably do not provide quality nesting habitat. Table 1 shows median snow depth on April 1 at 74 snow course sites. While these are point data, it is likely that points with greater depths indicate settings with more of the landscape covered with snow. Several patterns are evident.
- Fifty percent of the time, the Central Nevada Basin and Range (CNBR) MLRA generally has a shallow snow depth, or no snow  at elevations below 7,400 to 7,600 ft, and deep snow depth  above 7,800 ft.
- Fifty percent of the time, the Malhuer High Plateau (MHP) generally has a shallow snow depth or no snow cover below 6,400 to 6,600 ft elevation.
- Fifty percent of the time, the Owyhee High Plateau (OHP) has substantially shallower snow depth below about 6,500 ft., than above 6,500 ft.
-    These data suggest there is an upper elevation constraint for areas that routinely (preliminarily defined as 50% of the time) potential habitat for nesting and early brood rearing. The more likely an area is covered by deep snow at the time of nest initiation the less likely it is suitable for nesting. Both a nest site and forbs are unavailable. Melt-out data from SNOTEL sites (Table 2) indicates that in Nevada melt-out in the MHP and OHP MRA’s coincides with the nest initiation period (late March to early April) at elevations below about 6,200 to 6,500 ft. Undoubtedly, melt-out also occurs at elevations up to 7,000 ft or higher, but the proportion of the landscape on which this occurs is unknown and influenced  by topographic and wind patterns that affect snow drift, wind-blow, and melt rates. The following research issues are evident:
- The proportion of the total landscape potentially inhabited by sage grouse that is typically covered by snow at the time of nest initiation is likely a critical limiting factor on the potential sage grouse population.
- Tall, steep, and narrow mountain ranges (Figure 1b) are more likely to have a higher proportion of their potential sage grouse use areas unavailable for sage grouse at the time of nest initiation. Much of the area will be above the snowline, and many steep north facing slopes are likely to have deep snow drifts at lower elevations. Forbs at the lowest elevations often desiccate by the time hatch occurs.
- Mid elevation mountain ranges (6,500 to 7,500 ft) with broad level crests, and plateau and mesa landforms (Figures 1a and 1c), with sufficient elevation to receive enough precipitation to produce abundant forbs, but low enough for early snow melt, should have most of their potential use areas available for nesting and early brood rearing, provided forbs are available during the early brood rearing period. These areas will have the highest sage grouse densities.
- As the total area available for nesting declines due to regular snow cover, the importance of predators may increase due to their potential concentration in a smaller area.

**Table 1. **Median snow depth (inches) and quartiles on April 1, at snow course sites throughout Nevada. Abbreviations for Major Land Resource Areas are as follows: CBM = Carson Basin and Mountains; CNBR = Central Nevada Basin and Range; H = Humboldt; MHP = Malhuer High Plateau; and OHP = Owyhee High Plateau.

## The lower elevation limit of the sagebrush belt used by nesting sage grouse is probably constrained by the availability and abundance of forbs at the end of the nesting period (late May to mid June), and/or that point in the early brood rearing period when chicks can safely move to landscape settings with more forbs and/or insects available. We have very little quantitative knowledge about the availability and nutrient quality of most forb species on most ecological sites throughout the temporal period from nest initiation through early brood rearing.

- Snowtel 	                  --------------------------------------Melt Out Date------------------------------------------
- _Site_	_Elev_	_MLRA_	_Earliest Date_	_1st Quartile_	_Median Date_	_3rd Quartile_	_Latest Date_
- Sheldon	5860	MHP	January 1	January 7	February 7	March 12	April 1
- Disaster Peak	6500	MHP	March 2	March 25	April 5	April 12	April 28
- Lamance Creek	6000	OHP	April 3	April 8	April 14	April 23	May 2
- Taylor Canyon	6200	OHP	January 1	March 2	March 26	April 6	April 28
- Big Bend	6700	OHP	April 2	April 7	April 17	April 26	April 29
- Buckskin Lower	6700	OHP	April 7	April 18	April 26	May 10	May 22
- Laurel Draw	6700	OHP	April 9	April 14	April 19	April 30	May 12
- Fawn Creek	7000	OHP	April 28	May 9	May 12	May 27	June 2
- Seventy-six Creek	7100	OHP	April 14	April 18	April 26	May 7	May 11
- Jack Creek Upper	7250	OHP	April 30	May 9	May 17	May 28	June 5
- Draw Creek	7325	OHP	April 12	April 19	April 30	May 5	May 19
- Lamoille #3	7700	OHP	April 14	April 18	May 7	May 21	May 29
- Bear Creek	7800	OHP	May 6	May 19	May 29	June 11	June 22
- Granite Peak	7800	OHP	May 6	May 11	June 2	June 14	July 1
- Hole in Mountain	7900	OHP	April 23	May 2	May 10	May 31	Sept 4
- Green Mountain	8000	OHP	April 7	April 26	May 19	May 23	June 2
- Dorsey Basin	8100	OHP	April 20	April 23	May 12	May 27	June 2
- Pole Creek	8330	OHP	May 12	May 26	June 1	June 13	June 26
- Corral Canyon	8500	OHP	May 8	May 16	May 23	June 9	June 21
- Goat Creek	8800	OHP	May 9	May 17	May 26	May 21	June 1
- Big Creek 7800’	7800	CNBR	May 9	May 9	May 22	June 1	June 12
- Diamond Peak	8000	CNBR	January 23	March 28	April 7	April 25	May 1
- Big Creek 8700’	8700	CNBR	May 10	May 15	May 24	June 11	June 22
- Berry Creek	9100	CNBR	May 7	May 25	May 30	June 16	July 4
- Ward Mountain 	9200	CNBR	April 12	April 17	May 8	May 17	June 15

**Table 3. **Selected Ecological Sites for the major sagebrush species in each Major Land Resource Area that has sage grouse populations in Nevada. Production data represent an average year. ARTRW = Wyoming Big Sagebrush; ARTRV = Mountain Big Sagebrush; ARNO = Black Sagebrush; ARAR = Low Sagebrush.

- 	Sagebrush	# of Sagebrush 	Elevation 	-------Annual Production (lbs/ac)-------
**            **_**Ecological Site**_	 _Species_	_Sites_ 	_Range (ft)_	_Site_	_Shrubs_	_Grasses_	_Forbs_
_**Humboldt MLRA**_**	****	****	****	****	****	****	**
-   Loamy 8-10 	ARTRW	        6	5000-6500	  600	  240	 330	  30
-   Steep North Slope 10-12	ARTRW		5500-6500	  600	    90	 420	  90
-   South Slope 10-12	ARTRW		5500-7000	  700	  175	 455	  70
-   Shallow Loam 10-14	ARTRW/ARTRV	        5	5000-7000	  400	  120	 240	  40
-   Loamy 10-12	ARTRW/ARTRV		5500-7000	  800	  240	 480	  80
-   Shallow Calcareous Loam 10-14	ARNO	        4	6000-7500	  500	  200	 250	  50
-   Claypan 12-12	ARAR	        2	5500-7000	  500	  175	 275	  50
-   Claypan 12-16	ARAR		6500-9500	  800	  240	 480	  80
-   Loamy slope 12-14	ARTRV	        4	6500-8500	1000	  250	 650	100
-   North Slope 14+	ARTRV		6500-8500	1200	  240	 840	120
-   Loamy Slope 14+	ARTRV		6500-9500	1700	  510	 850	340
-   South Slope 12-16	ARTRV		7000-9000	1100	  220	 715	165
_**Malhuer High Plateau MLRA**_**	****	****	****	****	****	****	**
-   Loamy 8-10	ARTRW	      12	4500-5500	  600	  210	 360	  30
-   Loamy slope 10--14	ARTRW		4500-6000	  700	  140	 490	  70
-   Granitic Loam 10-12	ARTRW		5000-6500	  500	  150	 300	  50
-   Ashy Slope 10-12	ARTRW		5500-6300	  700	  140	 490	  70
-   Deep Loamy 10-12	ARTRW/ARTRV	        8	5000-6000	1000	  350	 550	100
-   Loamy 10-12	ARTRW/ARTRV		5500-6500	  900	  270	 540	  90
-   Loamy Fan 10-12	ARTRW/ARTRV		5500-6700	  900	  180	 630	  90
-   Ashy Loam 10-12	ARTRW/ARTRV		5700-6300	1100	  220	 770	110
-   Claypan 10-14	ARAR	      10	5500-7000	  700	  175	 455	  70
-   Ashy Claypan 10-14 (cool)	ARAR		5800-7000	1000	  300	 600	100
-   Claypan 14-16	ARAR		6500-8000	  700	  175	 455	  70
-   Shallow Loam 14+	ARAR		7000-8500	  600	  300	 390	  90
-   Loamy 12-14	ARTRV	      17	5500-7000	1300	  390	 845	195
-   Granitic South Slope 12-14	ARTRV		5500-8000	  800	  240	 480	  80
-   Granitic Slope 14-16	ARTRV		6000-8500	  700	  210	 385	105
-   Loamy Slope 16+	ARTRV		6500-7500	1500	  450	 750	300
-   Stony South Slope12-16	ARTRV		6500-8000	1000	  200	 700	100
-   Loamy 14-16	ARTRV		6500-8500	1200	  360	 720	120
-   Loamy 16+	ARTRV		6500-9000	1800	  270	1260	270
_**Owyhee High Plateau MLRA**_**	****	****	****	****	****	****	**
-   Loamy 8-10	ARTRW	        4	5500-6000	  600	  180	 390	  30
-   South Slope 8-12	ARTRW		5500-6500	  700	  105	 560	  35
-   Ashy Loam 8-10	ARTRW/ARTRV	        5	5200-5800	  600	  180	 360	  60
-   Loamy 10-12	ARTRW/ARTRV		5500-6500	  800	  200	 520	  80
-   Shallow Clay Loam 10-14	ARNO	        4	5500-7000	  500	  175	 275	  50
-   Shallow Clay Slope 10-14	ARNO		6000-7000	  375	  150	 187	  38
-   Claypan 10-12	ARAR	        6	5500-6500	  600	  180	 360	  60
-   Cobbly Claypan 8-12	ARAR		5500-7000	  400	  140	 220	  40
-   Claypan 12-16	ARAR		6000-8000	  700	  175	 420	105
-   Claypan 16+	ARAR		7000-8500	  600	  120	 390	  90
-   Loamy Slope 12-16	ARVA	        9	5500-8000	1000	  250	 600	150
-   South Slope 12-14	ARVA		6000-8500	  900	  225	 585	  90
-   Loamy 14-16	ARVA		7000-9000	1100	  220	 770	110
-   Shallow Loam 16+	ARVA		8200-9000	  700	  245	 385	  70
_**Central Nevada Basin and Range MLRA**_**	****	****	****	****	****	**
-   Loamy 8-10	ARTRW	        8	5000-6500	  600	  270	 300	  30
-   Gravelly Clay 10-12	ARTRW		6300-6800	  600	  210	 330	  60
-   Calcareous Loam 10-14	ARTRW/ARTRV	        5	6000-7500	  700	  245	 420	  35
-   Loamy 10-12	ARTRW/ARTRV		6400-7000	  800	  200	 520	  80
-   Shallow Calcareouos Loam 8-10	ARARN	        8	5000-6500	  450	  202	 225	  23
-   Shallow Calcareouos Loam 10-14	ARARN		6000-7500	  600	  210	 360	  30
-   Shallow Clay Loam 12-14	ARARN		7200-7500	  600	  210	 360	  30
-   Claypan 12-14	ARAR	        6	6300-8200	  600	  240	 300	  60
-   Cobbly Clayapn 12-14	ARAR		6800-8600	  350	  157	 140	  53
-   Calcareous Claypan 14-16	ARAR		7200-9200	  600	  240	 300	  60
-   Claypan 14+	ARAR		7500-9500	  500	  125	 325	  50
-   Gravelly Clay 12-14	ARTRV	      10	6400-8200	  700	  210	 385	105
-   Loamy 12-16	ARTRV		6500-8200	1200	  420	 660	120
-   Shallow Loam 10-14	ARTRV		6500-8200	  500	  150	 300	  50
-   Calcareous Loam 14-16	ARTRV		6500-8200	  900	  270	 540	  90
-   Gravelly Clay 14+	ARTRV		7500-8500	  700	  210	 420	  70
-   Loamy 16+	ARTRV		8000-9500	1200	  420	 660	120
-   Calcareous Loam 16+	ARTRV		8500-9500	1100	  440	 550	110

-  Table 3 indicates that the number of sagebrush Ecological Sites varies widely between MLRA’s. Also, sagebrush sites within an MLRA have inherent differences in their capability to produce forbs. In general, the Humboldt and other MLRA’s in west-central Nevada have substantially fewer sagebrush ecological sites than Malhuer High Plateau, Owyhee High Plateau, and Central Nevada Basin and Range MLRA’s. Within each MLRA, low elevation Wyoming big sagebrush and black sagebrush sites have the lowest forb production. Appropriate shrubs may be available for nest sites (particularly Wyoming sagebrush sites), but forb production is lower than for most other sagebrush sites. Wyoming big sagebrush sites with good forb production typically are restricted to north slopes and/or higher elevations. Both situations are likely to have more snow cover and/or colder soil. Snow cover will limit nest site availability, while both snow cover and cold soils will delay the emergence and growth (availability) of forbs. Low sagebrush sites typically have more forb production than Wyoming sagebrush sites, and often two or tree times more (Table 3). The Humboldt MLRA has the fewest low sage sites, and only one low sagebrush site that occurs below 6,500 ft elevation, where the bulk of the Wyoming sagebrush sites occur. The Malhuer High Plateau and Owyhee High Plateau MLRA’s each have more low sagebrush sites, and several or more low sagebrush sites that occur throughout the same elevation range (5,000 to 6,500 ft) as the Wyoming sagebrush sites. The Central Nevada Basin and Range MLRA has numerous low sagebrush sites, but most occur above 6,500 to 7,500 ft elevation, where snow cover is more likely to persist at the time of nest initiation.
-  If forb abundance is a critical determinant for nest success, and snow cover limits the area available for nesting to areas largely below about 6,500 ft to 7,000 ft (depending on geographic location), it is apparent that a heterogeneous mix of sagebrush sites is an important criteria that determines an areas intrinsic potential to produce a large or small sage grouse population.  Some ecological sites probably are more important for nest sites, while other ecological sites provide more high quality forage for hens throughout the entire reproductive period. Furthermore, the size and shape of these patches (i.e., spatial arrangement and connectivity) may have an important influence on overall habitat potential, particularly with respect to the effects of predation. Biologists and land managers have a very poor understanding about relationships between topography, snow cover and melt-out, the patchiness of different sagebrush plant communities and the availability of nest sites and forbs.
- A comparison of Figures 2 and 1b illustrates the importance of understanding the fore-mentioned  relationships. The foreground of both figures has a similar elevation range. Figure 2 shows the heterogeneous mix of low sagebrush and Wyoming sagebrush sites, with  riparian areas also present on the landscape. Within close proximity to one-another there are sites with tall shrubs for nesting, and sites that produce large quantities of forbs. The large tract of sagebrush in Figure 1b lacks the forbs necessary for high nest success. The ratio of acres per sage grouse is about 223 for the area in Figure 2 and over 1,000 for the area shown in Figure 1b.

- Photo By Gary Back

- Figure 2. Heterogeneous mixture of low sagebrush, big sagebrush, and riparian areas on bench land between 6,000 and 6,300 ft elevation.

- The intrinsic potential of a management unit to produce sage grouse cannot be changed through management. The population within the unit at any given time, however, may be toward the high or low end of the areas potential, based upon the composition and structure of the plant communities in the management unit. Landscapes with a poor mix of sagebrush ecological sites, and/or much of the area  covered with snow at the time of nest initiation and incubation will have smaller populations. Sagebrush ecological sites, however, progress through phases of plant succession (Figure 3).  Biologists and land managers have virtually no understanding about how vegetation management for heterogeneous successional phases within large homogeneous communities (e.g., Figure 1b) influences the size of sage grouse populations. Managers desperately need information about the response of sage grouse to vegetation manipulations, the optimal size and shape of successional patches, the response of different ecological sites to different  manipulation techniques, and the longevity of vegetation manipulations by ecological sites within MLRA’s.

**Figure 3. General pattern of plant succession in sagebrush plant communities.**

- Table 4 displays a  variety of data from 47 sage grouse population management units in Nevada.  When population size is standardized on an acres per bird basis there are clear emergent patterns that support the concepts presented in this paper. There are five PMU’s whose general topography is broad, rounded mountain ranges, with most of the area below 7,500 to 8,000 ft elevation. All  have among the lowest acres/sage grouse ratios, with four being among the lowest five ratios. Both PMU’s that were classified as having a predominately plateau or mesa landform had relatively small acre/sage grouse ratios. All of these sites occur in the two MLRA’s with both a wide variety of sagebrush ecological sites across all sagebrush species, and sagebrush ecological sites that produce an abundance of forbs at low elevations. Virtually all PMU’s that were classified as having the classical Basin and Range topography (Figure 1b) have acre/sage grouse ratios greater than 300, with many well over 1,000. The wide variation in acre:sage grouse ratios for these areas  begs the following question: Is there a relationship between the number of sagebrush sites in those management units, their spatial arrangement and size, and their successional state that affects the ordering of the ratios?

**Conclusions**: There appear to be landscape level bio-physical processes that affect the structure and composition of management units inhabited by sage grouse. This structure and composition appear to influence the availability and abundance of forbs, which is likely to be key determinant in a management units intrinsic ability to have or sustain a relatively low ratio of acres/sage grouse. These general relationships indicate a desperate need to expand research about sage grouse to address landscape level issues, particularly the spatial and temporal distribution of forbs and how their availability influences potential population size. This research needs to integrate across scales that include the nest site, the nest area, patch size and shape, the role of a mosaic of patches, heterogeneity within mosaics, and the processes that control the presence and abundance of critical habitat elements (e.g., forbs, shrub canopy morphology) across landscapes. Knowledge about a management unit’s intrinsic ability to produce forbs (and other critical habitat elements) when sage grouse require comparatively high amounts of them has important implications for management decisions about habitat improvement through vegetation/habitat manipulation. This presentation has largely focused on breeding and early brood rearing habitat. The concepts are equally applicable to late brood rearing areas, and other habitat elements not discussed.

**Literature Cited:**
- Schroeder, M. A., J. R. Young, and C. E. Braun. 1999. Sage Grouse: Centrocercus urophasianus. In: The Birds of North America, No. 425 ( A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
- Schultz, B. W. 2004. Analysis of studies used to develop herbaceous height and cover guidelines for sage grouse nesting habitat. University of Nevada Cooperative Extension Special Publication, SP-04-11. 25 pp.** **

- 		Topographic 	Population	Acres in
- _PMU_	_MLRA_	_Classification_	_Estimate_	_PMU_	_Acres/Bird_
- Lone Willow	MHP	1	  9,200	   476,533	       52
- Islands	OHP	1	  3,127	   270,163	       86
- Sheldon	MHP	3	  3,186	   476,850	     150
- O’Neil Basin	OHP	1	  5,863	1,014,660	     173
- Gollaher	OHP	1	  4,852	   912,217	     184
- Black Rock	MHP	4	  1,100	   223,177	     203
- North Fork	OHP	4	  7,762	1,731,231	     223
- Santa Rosa	OHP	4	  4,196	   938,793	     224
- Vya	MHP	1	  2,199	   501,230	     228
- Snake	OHP	4	  2,336	   538,120	     230
- Reese River	CNBR	2	  5,135	1,348,382	     263
- Massacre	MHP	3	  4,242	1,135,260	     268
- Diamond	CNBR	2	  3,125	   841,396	     269
- Cortez	OHP	4	  2,170	   601,190	     277
- Monitor	CNBR	2	10,780	3,224,079	     299
- Toiyabe	CNBR	2	  3,725	1,126,966	     303
- Pine Forest	MHP	4	     400	   121,697	     304
- Tuscarora	OHP	4	  4,107	1,385,112	     337
- Jackson 	HUMBOLDT	2	     200	     75,604	     378
- Buffalo/Skedaddle	MHP	4	  3,896	1,475,506	     379
- Battle Mountain	CNBR	2	     270	   107,515	     398
- South Fork	OHP	2	  3,277	1,369,936	     418
- Steptoe-Cave	CNBR	2	  1,877	   835,463	     445
- PahRah	CBM	2	     295	   151,644	     514
- Ruby Valley	CNBR	2	  2,141	1,115,040	     521
- Eugenes	HUMBOLDT	2	     107	     59,403	     555
- Desotoya	CNBR	2	     858	   512,000	     597
- Desert	OHP	4	  1,463	   916,648	     627
- Virginia	CBM	2	     295	   204,562	     695
- Schell/Antelope	CNBR	2	  1,680	1,207,858	     719
- Shoshone	CNBR	2	     875	   663,289	     758
- Three Bar	CNBR	2	  1,004	   789,617	     786
- Trinity	FLA	2	       75	     68,026	     907
- Sonoma	HUMBOLDT	2	     587	   541,596	     923
- Butte/Buck	CNBR	2	  2,912	2,814,640	     967
- Nightengale	FLA	2	       38	     37,718	     993
- Lincoln	CNBR	2	  1,066	1,403,975	  1,318
- Majuba	FLA	2	     250	   334,754	  1,339
- Steptoe/Cave	CNBR	2	     460	   835,284	  1,818
- East Valley	CNBR	2	     421	   790,647	  1,880
- Shawave	FLA	2	       25	     49,624	  1,985
- Humboldt Range	HUMBOLDT	2	       88	   175,621	  1,996
- Fish Creek	CNBR	2	     120	   241,337	  2,011
- Limbo	FLA	2	       25	     68,880	  2,755
- Spring/Snake	CNBR	2	     403	1,134,174	  2,814
- Clan Alpine	FLA	2	       74	   500,135	  6,805
- East Range	HUMBOLDT	2	       30	   314,845	10,495
- Stillwater	FLA	2	       15	   249,313	16,621

- Table 4.  Population management units, their geographic location, topographic classification, sage grouse population, size, and ratio of acres per bird for 48 PMU’s in Nevada.