Landscape Collaborative Grazing and Greater Sage Grouse Survival

Final Report for SW13-056

Project Type: Research and Education
Funds awarded in 2013: $339,552.00
Projected End Date: 12/31/2016
Region: Western
State: Montana
Principal Investigator:
Dr. Bok Sowell
MSU- Animal & Range Sciences
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Project Information

Abstract:

We have combined three years of information for most of this report.  Average nesting success for three years was 34%.  Cattle in our study area are not grazing in sagebrush habitats frequently during the sage-grouse nesting season.  Nesting success was greatest in mountain big sagebrush (45%), less in three-tip sagebrush (30%), and lowest in basin big sagebrush (16%).  The presence of fences was the only infrastructure associated with grazing that had an effect on nest success.  Avian predators may use them as perches or mammals may use them as search corridors.  Successful nests were 250 meters further from fence lines than unsuccessful nests.  Cattle grazing appears to have little to no effect on grass utilization and sage-grouse home range size in the brood rearing stage.  Information collected over the last three years suggests management practices which maintain unfragmented blocks of mountain big sagebrush and three-tip sagebrush habitat types appear to have the greatest potential to maintain sage-grouse populations in the Centennial Valley, MT.

Project Objectives:

Objective 1: Expand capture design to include more birds

Objective 2: Estimate cattle grazing influences on sage-grouse nesting

Objective 3: Estimate influence of habitat type on nesting success

Objective 4: Estimate grazing influences on sage-grouse brood home range size

Objective 5: Estimate the effects of grazing infrastructure on brood survival (2014-2016)

Introduction:

The purpose of this project is to examine the effects of cattle grazing on sage-grouse (Centerocercus urophasianus) habitat, nesting success, hen survival and brood survival in the Centennial Valley of Montana.  The decline of sage-grouse over the years has been attributed to cattle grazing, even though several reviewers have stated there are no controlled studies which have examined this relationship.  If the sage-grouse is listed as a Threatened or Endangered Species under the Endangered Species Act, it will have a large impact on livestock grazing across the western United States, since it is the most dominant land use.

Our original study objective in 2014 was to capture and radio-collar sage-grouse hens from 5 leks and test the effects of cattle grazing on nest survival, brood survival and hen survival over two years.  Unfortunately, the hens failed to nest and raise broods in sufficient numbers where we controlled grazing on 10,000 acres of land.  In the second year of our study (2015), we captured hens from three additional leks and attempted to increase our chances of having sage-grouse in areas occupied by cattle.  We also expanded our objectives to include other factors which would influence sage-grouse survival, and we secured outside funding for an additional year of study. 

Cooperators

Click linked name(s) to expand
  • Brad Bauer
  • Craig Carr
  • Kyle Cutting
  • Dr. Rachel Endecott
  • Mike Frisina
  • Allen & Yvonne Martinell
  • Dr. Bok Sowell
  • JP (John Paul) Tanner
  • Bryan Ulring

Research

Materials and methods:

In 2014, 51 females were captured from 5 leks and radio collared.  These birds dispersed to 50,000 acres.  In 2015, 58 sage-grouse hens were captured from 8 leks and they dispersed to 97,581 acres. In 2016, 55 sage-grouse hens were captured from 8 leks and they dispersed to 144,926 acres.  Vegetation surveys were conducted at nests and random sites within 3 m of the nest and randomly generated points.  Bird locations were taken 2-3 times per weeks.  All habitat variables that were in the top models as determined by General Linear Model procedures were included.  Grazing utilization levels were determined by establishing height-weight curves for the dominant grass and forb species.  Estimating the effects of roads, water tanks, fence lines and cattle paths, elevation, heat loading and vegetation characteristics was determined using General Linear Models.  Nests were defined as successful if at least one egg hatched at the end of the incubation period.  Broods were monitored until chicks were 30 days old.  Broods were defined to be successful if at least one chick survived 30 days from hatching.

Research results and discussion:

Objective 1: Expand capture design to include more birds.

In 2014, 51 females were captured from 5 leks and radio collared.  These birds dispersed to 50,000 acres.  In 2015, 58 sage-grouse hens were captured from 8 leks and they dispersed to 97,581 acres. In 2016, 55 sage-grouse hens were captured from 8 leks and they dispersed to 144,926 acres.

Objective 2: Estimate cattle grazing influences on sage-grouse nesting.

Cattle grazing in our study area of the Centennial Valley generally does not occur until most of the sage-grouse have completed nesting. In 2014 and 2015 our study focused on direct effects of cattle grazing. We only had two nests that experienced grazing effects by cattle (Table 1).

Table 1: Nests in pastures with and without cattle in 2014 and 2015

 

2014

2015

Total

Nests with Cows

  2

  0

  2

Nests without Cows

39

49

88

Total Nests

41

49

90

In addition to looking at direct effects of cattle presence on nest site selection, we also looked at indirect effects resulting from cattle grazing infrastructure (roads, fence lines, water tanks) and presence (cattle trails and density) over summers 2014-16 (Table 2). Distance to the nearest cattle path had a moderate effect on selection of nest sites for sage-grouse. Extended use by cattle in a given area, such as concentrated point sources (e.g. water tanks), may increase the number and linear distances of cattle paths in a given area. This in turn may increase sage-grouse nesting use of these areas. We suspect sage-grouse utilize these paths as travel corridors to and from their nests, and to aid in ease of movement throughout dense stands of sagebrush.

Table 2: Nest site selection in relation to cattle grazing infrastructure in 2014, 2015, and 2016.

 

Variable

Nest Sites (n = 156)

Random Nest Sites (n = 372)

P-value

Distance to Road (meters)

260

 

285

 

0.17

Distance to Water tank (meters)

1665

 

1845

 

0.13

Distance to Fence line (meters)

527

 

498

 

0.30

Distance to Cattle Path (meters)

42

 

36

 

0.10

 

 

Distance to fence line influenced nest survival (Table 3). On average, successful nests were 258 m further from fence lines than unsuccessful nests. Avian predators oftentimes use fence posts as perches, which could explain this difference. No other difference existed in terms of its mean grazing infrastructure influence on nest survival.

Table 3: Apparent nest survival in relation to cattle grazing infrastructure in 2014, 2015 and 2016.

Variable

Successful Nest (n = 53)

Unsuccessful Nest (n = 103)

P-value

Distance to Road (meters)

270

 

255

 

0.38

Distance to Water tank (meters)

1544

 

1899

 

0.13

Distance to Fence line (meters)

697

 

439

 

0.01

Distance to Cattle Path (meters)

44

 

40

 

0.33

Cow Pies (quantity)

8

 

9

 

0.34

 

Sage-grouse selected nest sites with more heat, including areas with more southerly aspects and steeper slopes (Table 4). Sage-grouse also selected habitats for nesting lower in elevation than available.

Table 4: Nest site selection in relation to abiotic factors, 2014, 2015 and 2016.

Variable

Nest Site

Random Site

P-value

Heatloading

0.76

0.75

  0.05

Elevation

2138

2171

    0.002

 

Elevation positively influenced nest survival (Table 5). Nests that hatched at least one young were found 55 m higher in elevation than unsuccessful nests. Our study area ranged in elevations from 2042 meters (6700 feet) to 2600 meters (8528 feet). 

Table 5: Apparent nest survival in relation to elevation and heatloading.

Variable

 

Successful Nests

Unsuccessful Nests

P-value

Heatloading

 

0.77

0.76

0.22

Elevation

 

2176

2119

  0.001

 

Sage-grouse selected nest sites with more dead grass, on average total height was 70 cm greater at nest sites than random sites (Table 6). For grass cover, forb cover, and species richness, sage-grouse selected nest sites with average values less than at random sites. These values could be driven by the large portion of female sage-grouse that nested in the big basin sagebrush habitat that has much lower grass, forb, and species richness than other sagebrush types.

Table 6: Nest site selection in relation to biotic (vegetative) indices.

Variable

Nest Site

Random Nest Site

P-value

Dead Grass Height (cm)

397

 

327

 

0.01

Grass Cover (%)

115

 

123

 

0.04

Forb Cover (%)

41

 

59

 

0.00

Shrub Cover (%)

38

 

37

 

0.29

Species Richness (number of spp.)

19

 

22

 

0.00

 

 Of all the nest sites selected, successful nests seemed to be positively influenced by less dead grass height, greater forb cover, and greater species richness (Table 7). On average, successful nests had a total dead grass of 70 cm less than unsuccessful nest sites, forb cover was 8% greater, and number of total species found at nest sites was 21 versus 18 at unsuccessful nest sites.

Table 7: Apparent nest survival in relation to certain vegetative indices.

Variable

Successful Nests

Unsuccessful Nests

P-value

Dead Grass Height (cm)

351

 

421

 

0.07

Grass Cover (%)

117

 

113

 

0.31

Forb Cover (%)

46

 

38

 

0.06

Shrub Cover (%)

39

 

37

 

0.26

Species Richness (number of spp.)

21

 

18

 

0.00

 

Objective 3: Estimate influence of habitat type on nesting success

At the end of the 2016 season, sage-grouse used 3,468 acres of low sagebrush, 7,587 acres of basin big sagebrush, 27,337 acres of three-tip sagebrush, and 69,795 acres of mountain big sagebrush.

Nesting success averaged 34% across all habitat types (Table 8). Sage-grouse did not nest in low sagebrush. Nesting success is usually dependent on factors that reduce predation rates.  Mountain big sagebrush plants provide the most cover for nests which would reduce predation due to increased concealment of the nest.

Table 8:  Nesting success (%) of sage-grouse by habitat type in the Centennial Valley, MT, 2014-2016.

Year

Mountain big sagebrush

Three-tip sagebrush

Basin big sagebrush

Low sagebrush

Overall

2014

59

44

15

N/A

43

2015

35

29

10

N/A

28

2016

42

18

24

N/A

30

Average

45

30

16

N/A

34

 

Objective 4: Estimate grazing influences on sage-grouse brood home range size

Grazing utilization levels averaged 4% in brood home ranges in 2014 and 2015. (Table 9). The maximum utilization level recorded in a brood’s home range was 14% (Table 9). Therefore, utilization levels were very low in brood home ranges. We did not measure utilization levels in brood home ranges in 2016.

Table 9: Grazing utilization levels in brood home ranges of broods in pastures with cattle across 2014 and 2015.

 

2014

2015

All

Average Utilization

  4%

3%

4%

Max Utilization

14%

13%

14%

 

There was no year effect (P = 0.66) in brood home range size, and brood home range size did not differ between grazed and ungrazed pastures (Table 10, 11, 12). The sample size for broods in pastures with cattle (n = 7) was low (Table 10), but two broods traveled >1 km into a pasture with cattle where they remained for over 2 weeks. We did not measure brood home ranges in 2016.

Table 10: Broods in pastures with cattle and without in 2014 and 2015.

 

2014

2015

Total

Broods with Cows

  5

 2

  7

Broods without Cows

  9

 8

17

Total

14

10

24

 

Table 11: Differences in overall brood home range size (acres) between years 2014 and 2015.

 

2014 (n = 11)

2015 (n = 8)

P-Value

Average Brood Home Range Size (acres)

252

351

0.66

 

Table 12: Differences in overall brood home range size acres) between pastures grazed and ungrazed by cattle in 2014 and 2015.

 

Grazed (n = 6)

Ungrazed (n = 13)

P-Value

Average Brood Home Range Size (acres)

368

225

0.35

 

There were no differences (P = 0.39) in grass heights between 2014 and 2015 (Table 13) in pastures with sage-grouse broods.  This suggests growing conditions in both years were similar and differences in sage-grouse nest and brood survival were not due to environmental factors, but we have not tested this hypothesis.

Table 13:  Average grass heights (cm) by year.

 

2014

2015

P-value

Number of Plots

107

72

 

Grass Height (cm)

  27

33

0.39

 

Grazing did not reduce (P = 0.18) average grass height in pastures with and without cattle for both years (Table 14).  This provides evidence that grazing levels in our original and expanded area did not alter grass height.  Since most studies have indicated increased grass height will increase sage-grouse survival, it is unlikely that grazing altered brood survival, but we have not analyzed this.

Table 14:  Influence of grazing on average grass height (cm) during brood-rearing of sage-grouse in the Centennial Valley, MT, 2014-2015.

 

Grazed

Ungrazed

P-value

Number of Plots

92

87

 

Grass Height (cm)

37

26

0.18

 

Seventy eight percent (35/45) of sage-grouse hens with broods used mountain big sagebrush and three-tip sagebrush vegetation types (Table 15). Less than one percent were found in big basin sagebrush.

Table 15: Habitat types used by broods across three years of the study.

 

Mountain big sagebrush

Three-tip sagebrush

Big basin

sagebrush

Mixture

Total

2014

  6

3

 

2

11

2015

  3

4

 

1

  8

2016

13

6

2

5

26

Total

22

13

2

8

45

 

Objective 5: Estimate the effects of grazing infrastructure on brood survival (2014-2016)

Broods that survived to 30-days of age were located closer to roads and water tanks than failed broods (Table 16). Successful broods were 129 m closer to roads and 385 m closer to water tanks on average compared to failed broods (Table 16). Successful broods closer to roads and water tanks could increase their movements, increase sighting distance, and increase vigilance of predator activity nearby.   However, successful broods were located on average 1.1 mile from the nearest water tank, but it is difficult to provide a biological reason for this finding.   

Table 16: Average distances (m) to fences, roads, and water tanks of successful (survived to 30-days old) and failed broods (died prior to 30-days of age)

 

Successful Broods

Failed Broods

P-Value

Fence distance (meters)

  613

  696

0.21

Road distance (meters)

  217

  346

  0.003

Water tank distance (meters)

1702

2088

0.08

 

Conclusion:

Current grazing practices in the Centennial Valley appear to have minimal effects on sage-grouse reproduction and survival during the nesting and brood rearing seasons.  Average nesting success was 34% across the 3-year study.  Cattle and sage-grouse generally overlap mostly during the brood-rearing period. Cattle had little effect on vegetation during the nesting and brood rearing season.  Cattle utilize a small portion of the total sagebrush landscape, which minimizes the chances of conflict between cattle and sage-grouse. We did not detect an influence of cattle on brood home range size, though we acknowledge the sample size was small. The only grazing effect we detected was that unsuccessful nests were closer to fence lines than successful nests.  Residual grass height did not influence nest survival as successful nests had less dead grass heights than successful nests. Sagebrush type and elevation appeared to have a stronger influence than livestock grazing on sage-grouse nest survival. Broods that survived to 30-days of age were found closer to roads and water tanks.  This suggests that grazing infrastructure attributes such as roads and water tanks currently do not have a negative influence on sage-grouse broods for the Centennial Valley of Montana.

Milestones 

Milestones for 2014:

  1. Recruited graduate students Kyle Cutting (Ph.D.) and Sean Schroff (M.S.).
  2. Captured 51 sage-grouse hens from 5 leks.
  3. Held 3 organizational meetings of Team, Montana Fish Wildlife & Parks, Bureau of Land Management and Natural Resource Conservation Service representatives.
  4. Measured sagebrush cover and herbaceous cover before cattle are introduced.
  5. Measured vegetation before and after grazing in areas of light, moderate and heavy use.
  6. Measured sagebrush cover and herbaceous cover at the nest.
  7. Hosted 2 field days on June 5, 2014 (30 participants) and September 11, 2014 (35 participants)
  8. Submitted Annual Report.

Milestones for 2015:

  1. Captured 58 sage-grouse hens
  2. Marked location of hens with and without cattle grazing
  3. Delineated habitat type use by hens and estimated nesting success
  4. Estimated brood home range size with and without cattle
  5. Estimated grazing effects on herbaceous vegetation and sage-grouse survival
  6. Estimated effects of habitat type on brood survival
  7. Meeting to discuss sagebrush habitat grazing management with US Forest Service, US Fish and Wildlife Service, Montana Fish, Wildlife & Parks, Greater Yellowstone Coalition, and cattle and sheep producers. August 6, 2015, Dillon, MT.
  8. Presented preliminary findings to scientists (Greater sage-grouse Grazing Research Meeting, hosted by Montana Fish, Wildlife & Parks and attended by researchers from Montana State University, Idaho Fish and Game, Idaho State University and Utah State University; November 4-5, 2015, Helena, MT.)
  9. YouTube video of project completed December 2015, Link sent to WSARE for approval. (https://www.youtube.com/watch?v=AVGeIBjHnqY)
  10. Submitted Annual Report.

Milestones for 2016:

  1. Captured and marked 55 sage-grouse hens with radio-transmitters
  2. Brought several ranchers together to discuss study findings, Lima, Montana
  3. Met individually with U.S. Forest Service and Bureau of Land Management regarding grazing implications, Dillon, Montana.
  4. Provided grazing recommendations to Montana Department of Natural Resource Conservation.
  5. Presented study findings to The Nature Conservancy, Montana Fish, Wildlife, and Parks, and Department of Natural Resource Conservation Service, Helena, Montana.
  6. Centennial Valley Association is promoting study results to ranching community.
  7. Results provide recommendation for grazing management in the Centennial Valley.
  8. Results presented to the Intermountain Section of the Society of Range Management, Nov 4, 2016. Bozeman, MT.
  9. Results support sustainable grazing practices in high-elevation sagebrush sites.
  10. Meeting with USFS, BLM, NRCS, USF&WS, and local land owners to present findings from this report. On Dec 12 and 21, 2016 in Lima and Helena, MT.
  11. Submitted Annual Report.
Research conclusions:

After three years of study we can conclude that livestock grazers of the Centennial Valley are already practicing sound management because they are not grazing in areas when sage-grouse are nesting.  It is also apparent that the community approach to providing grazing opportunities by public and private land owners has led to very low grazing pressure which has resulted in very little vegetation alteration.  Our results lead us to conclude that current grazing practices in the Centennial Valley, MT have minimal to no impact on sage-grouse nesting success or brood home range sizes.  We did find evidence that suggests that fences might alter nesting success.  Our greatest impact is to document that regional guidelines developed for grazing to increase residual herbaceous cover may not benefit sage-grouse in specific sagebrush types.  This information has been distributed to livestock producers and land managers across the intermountain west.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

 Video:  YouTube video of project completed December 2015. Posted on WSARE webpage. (https://www.youtube.com/watch?v=AVGeIBjHnqY)

Schroff, S. R., Cutting, K. A., Carr, C., Frisina, M., McNew, L. B., Sowell, B. Fine-scale nest site selection of greater sage-grouse in the Centennial Valley, Montana. Canadian Journal of Zoology, 14 pages. SUBMITTED

Schroff, S.R.  2016.  Nest Site Selection and Brood Home Range of Greater Sage-Grouse (Centerocercus Urophasianus) In The Centennial Valley, Montana.  M.S. Thesis. Montana State University, Bozeman, Montana.

Outreach:

Held 3 meetings of Team, Montana Fish Wildlife & Parks, Bureau of Land Management and Natural Resource Conservation Service representatives in 2014.

Hosted 2 field days on June 5, 2014 (30 participants) and September 11, 2014 (35 participants)

Meeting to discuss sagebrush habitat grazing management with US Forest Service, US Fish and Wildlife Service, Montana Fish, Wildlife & Parks, Greater Yellowstone Coalition, and cattle and sheep producers. August 6, 2015, Dillon, MT.

Presented preliminary findings to scientists (Greater sage-grouse Grazing Research Meeting, hosted by Montana Fish, Wildlife & Parks and attended by researchers from Montana State University, Idaho Fish and Game, Idaho State University and Utah State University; November 4-5, 2015, Helena, MT.)

Brought several ranchers together to discuss study findings, Lima, Montana in 2016.

Met individually with U.S. Forest Service and Bureau of Land Management regarding grazing implications, Dillon, Montana. 2016

Provided grazing recommendations to Montana Department of Natural Resource Conservation. 2016.

Presented study findings to The Nature Conservancy, Montana Fish, Wildlife, and Parks, and Department of Natural Resource Conservation Service, Helena, Montana. 2016.

The Centennial Valley Association is promoting study results to ranching community. 2016.

Results presented to the Intermountain Section of the Society of Range Management, Nov 4, 2016.  Bozeman, MT.

Meeting with USFS, BLM, NRCS, USF&WS, and local land owners to present findings from this report. On Dec 12 and 21, 2016 in Lima and Helena, MT.

Project Outcomes

Project outcomes:

We did not measure the economic impact of conservation practices needed to secure habitat for sage-grouse.  However Torell et al. (2014) estimated these impacts for ranches in several states including Wyoming.  They used profit maximizing models to estimate the economic value of public land forage to ranches that are dependent on public lands.  Using their estimates for Wyoming ranches, an AUM would be worth $15/AUM if they lost these lands to grazing closures to protect sage-grouse populations.  In the 2016 study area of the Centennial Valley that was comprised of 144,926 acres, 30% of the land is in federal ownership.  That would equal 43,478 acres of land that would be lost if grazing was not permitted.  The average suggested stocking rate is 3 ac/AUM so the valley ranchers have the potential to lose 14,493 AUMs of grazing or $217,389 annually ($15/AUM) if the federal lands were no longer available to livestock producers in the Centennial Valley.  Although we were unable to measure some of the effects of cattle grazing on nesting sage-grouse, there is good evidence from our study that livestock grazing is not one of the major factors which influences sage-grouse survival.  Therefore, management of sage-grouse on federal lands in this valley should not include livestock removal for biological and economic reasons.

Literature Cited:

Torell, L. A., Rimbey, N., Tanaka, J., Taylor, D., Ritten, J., & Foulke, T.  2014. Ranch-Level Economic Impacts of Altering Grazing Policies on Federal Land to Protect the Greater Sage-Grouse. Journal of Rangeland Applications1, 1-13.

Farmer Adoption

 Most of the ranchers in the Centennial Valley have already adopted practices which minimize cattle grazing risks to sage-grouse.  We have merely confirmed these results with our study.  Since we are working with state and federal land managers, we have shared these finding with them to convey to their clientele.

Recommendations:

Areas needing additional study

Trying to conduct a controlled experiment which examines the effects of livestock grazing on sage-grouse remains an elusive goal.  We know of two other long-term studies in Idaho and eastern Montana which adopted a design similar to ours.  However, every study that examines sage-grouse, habitat attributes and livestock grazing gives us more information to improve our management.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.