Dustin H. Ranglack Ph.D. Candidate dhranglack@gmail.com @dhranglack Competition on the range: Science vs. perception in a bison-cattle conflict in the western USA Dustin H. Ranglack, Susan Durham, and Johan T. du Toit Genome.gov Tringa.org Dustin H. Ranglack Ph.D. Candidate dhranglack@gmail.com @dhranglack

@dhranglack Introduction Integration of local ecological knowledge (LEK) into adaptive management But science is still needed nature.org

Wildlife-livestock conflict @dhranglack Wildlife-livestock conflict World-wide negative view towards native large herbivores Disease Competition Near eradication of many wildlife species Ryan Sensenig

@dhranglack Bison Currently ~500,000 ~20,000 in conservation herds Intensively managed; fragmented landscapes; cattle introgression Perceived competition with livestock limiting large-scale restoration

@dhranglack Predictions If bison significantly reduce forage availability for cattle: Bison visitation a significant predictor of grass biomass depletion If bison are the main wildlife competitor with cattle for grazing resources: Bison and cattle the two predominant grass consumers

Study site Henry Mountains (HM) Colorado Plateau Arid/semi-arid @dhranglack Study site Henry Mountains (HM) Colorado Plateau Arid/semi-arid Isolated Public land (BLM) Desert grassland/shrubland PJ and mixed conifer forest Subalpine grassland and aspen

HM bison Introduced in 1940s Co-mingle with cattle Free-ranging @dhranglack HM bison Introduced in 1940s Free-ranging Genetically pure Disease Free Huntable ~325 adults post-hunt Co-mingle with cattle

@dhranglack HM bison conflict Drought

Other HM grazers Lagomorphs Black-tailed jackrabbits @dhranglack Other HM grazers Lagomorphs Black-tailed jackrabbits Desert cottontail rabbits Bill Bouton Alan Vernon

@dhranglack Goals Measure rancher perceptions of wildlife-livestock conflict in the HM Determine relative impacts of bison, cattle, and lagomorphs on HM rangeland

Rancher survey Questionnaire mailed to 21 ranchers @dhranglack Rancher survey Questionnaire mailed to 21 ranchers What are the biggest issues? Main wildlife competitors? Predator control?

Rancher survey 12 responses (57.1% of ranchers; 70.9% of cattle) @dhranglack Rancher survey 12 responses (57.1% of ranchers; 70.9% of cattle) Competition for forage biggest concern Wildlife competitors (high=3, low=1) Bison: Mean: 2.18, SE: 0.25 Lagomorphs: Mean: 1.11, SE: 0.11 All felt that coyotes should be controlled

@dhranglack Exclosure sites

Experimental design At each site (n=20): @dhranglack Experimental design At each site (n=20): 1 - 8’x8’ exclosure (bison + cattle out) 1 - 8’x8’ exclosure (bison + cattle + lagomorphs out) 1 - 8’x8’ reference plot (all grazers in) Total of 40 exclosures and 20 reference plots

@dhranglack Site layout

Data collection Oct. 2011: set up Oct. 2012: clipped @dhranglack Data collection Oct. 2011: set up Oct. 2012: clipped Separated into grass, forb, shrub, cactus Dried and weighed

@dhranglack October 2011, Site #19 Partial Exclosure Full Exclosure

@dhranglack October 2012, Site # 19 Partial exclosure Full exclosure

@dhranglack Predictions Bison visitation a significant predictor of grass biomass depletion Bison and cattle the two predominant grass consumers

@dhranglack Bison 44 GPS collars deployed on HM bison

Bison RDI RDI: Relative Density Index RDIi = Si/A @dhranglack Bison RDI RDI: Relative Density Index RDIi = Si/A Si = bison locations / sq. km around site i A = bison locations/ sq. km in the area comprising the habitat in which site i occurs Log transformed for analysis

Bison RDI RDI >0: higher than expected bison use @dhranglack Bison RDI RDI >0: higher than expected bison use RDI <0: lower than expected bison use Sam Abell

@dhranglack Expected Prediction 1

@dhranglack Observed

@dhranglack Prediction 1 Bison visitation a significant predictor of grass biomass depletion

@dhranglack Predictions Bison visitation a significant predictor of grass biomass depletion Bison and cattle the two predominant grass consumers

@dhranglack One-way, RBD ANOVA Significant differences among reference, partial, and full exclosures (p < 0.05) Large herbivores = 13.9 g/m2 (p = 0.005) Lagomorphs = 7.2 g/m2 (p = 0.048) How much of the large herbivore effect is due to bison vs cattle? Using ‘animal days’ to determine the relative impacts of each.

Animal days (# of individuals) * (# of days in the area) @dhranglack Animal days (# of individuals) * (# of days in the area) Bison = 21,415 days Cattle = 81,949 days

Grass use Cattle: 11.0 g/m2 Lagomorphs: 7.2 g/m2 Bison: 2.9 g/m2 @dhranglack Grass use Cattle: 11.0 g/m2 Lagomorphs: 7.2 g/m2 Bison: 2.9 g/m2 James Marvin Phelps

@dhranglack Overall grass use

Prediction 2 Bison and cattle the two predominant grass consumers @dhranglack Prediction 2 Bison and cattle the two predominant grass consumers

Adaptive management Integrating LEK must be done carefully @dhranglack Adaptive management Integrating LEK must be done carefully While useful in many cases, it might be: based on misunderstanding not matched with current conditions biased to suit political needs Management decision based on perceptions are unlikely to lead to a satisfactory outcome Science should provide direction

Discussion Trophic cascade from predator removal? @dhranglack Discussion Trophic cascade from predator removal? $1.35 M spent annually in Utah on predator control Hope for bison restoration Impacts on cattle overstated

@dhranglack Acknowledgements dhranglack@gmail.com Chris Holcomb