Elk (Cervus elaphus L.) and cattle (Bos taurus L.) co-occur on rangelands throughout western North America. Literature regarding range relations between elk and cattle, however, is contradictory, describing interspecific competition in some cases and complementary or facilitative relations in others. A better understanding of how sympatric elk and cattle behave at fine spatiotemporal scales is needed to properly allocate resources for these species. We used intensively sampled Global Positioning System (GPS) tracking data (1-sec intervals) to classify elk and cattle behavior and investigate their activity and movement strategies in the Blue Mountains of northeastern Oregon, United States, during summer and fall 2007. An ensemble classification approach was used to identify stationary, foraging, and walking behavior classes within the GPS datasets of mature beef and captive elk cows grazing in forested pastures during two randomized experiments, one in summer and the other fall. During summer, elk traveled farther per day, had larger walking budgets, exhibited more and longer walking bouts, and had higher walking velocities than beef cows. Cattle tended to emphasize intensive foraging over extensive movement and thus displayed larger foraging budgets and longer foraging bouts than elk. Site-by-species interactions, however, were detected for some foraging responses. During fall, when forage quality was limiting, elk exhibited a more foraging-centric mobility strategy while cattle emphasized an energy conservation strategy. These differing movement and energetic strategies tended to support the concept that elk and cattle occupy differing behavioral niches. Extensive foraging by elk and intensive foraging by cattle during summer correspond well with behaviors expected for elk searching out forbs in graminoid-dominated habitats and cattle foraging intensively on graminoids. Behaviors exhibited in the fall were consistent with elk continuing to exercise more selectivity among the available forage than cattle. These differing strategies, consequently, would moderate the potential for direct interspecific competition during summer and fall.

Prescribed fire has long been used worldwide for livestock and wildlife management. Prescribed fire effects on activity budgets and movement path characteristics of grazing animals, however, remain largely unknown. We evaluated whether prescribed-fire treatments in mesic sagebrush steppe affect cattle behaviors, which could influence foraging efficiency and, ultimately, impact animal productivity. Mature, lactating beef cows grazing within two study areas located in the Owyhee Mountains of southwestern Idaho, United States were tracked with Global Positioning System collars for 2 yr before and 5 yr after fall prescribed fire. Tracking data were then classified into stationary, foraging, and traveling activity types on the basis of movement distance and velocity thresholds. After fire, cattle in burned sites tended to increase their foraging activity budgets, bout durations, bout counts, and path lengths relative to prefire and cattle in unburned sites. Fire did not affect steepness of cattle foraging paths. Prescribed fire in mesic sagebrush steppe can be used to create opportunities for cattle to improve foraging efficiency by altering their activity budgets and movement path characteristics. Any consequent improvements in foraging efficiency could, in turn, promote increased rates of weight gain, better body condition, enhanced reproductive success, and ultimately, more pounds of beef for market.

Prescribed fire can release herbaceous forages from woody plant competition thus promoting increased forage plant production, vigor, and accessibility. Prescribe fire also consumes standing litter thereby improving forage quality and palatability. Consequently, prescribed fire is commonly considered an effective tool for manipulating livestock distribution on rangelands. Efficacy of this tool on mesic sagebrush steppe, however, has received little research attention. Beginning in 2001, resource selection by beef cows under a mid-summer (July) grazing regime was evaluated using global positioning system (GPS) collars for 2 years prior to and for up to 5 years after a fall prescribed fire was conducted on mesic sagebrush steppe in the Owyhee Mountains of southwestern Idaho, USA. Cattle selected for burned areas during the first, second, and fifth postfire years. Cattle had exhibited neutral selectivity towards these areas, during one of the two prefire years. Burning in the uplands reduced cattle use of near-stream habitats but only during the second postfire year. Differences in phenological timing of grazing may account for differences in cattle response to burning noted between this study and one conducted nearby under a spring (May) grazing regime. This is a case study and caution should be taken in extrapolating these results.

Crested wheatgrass (Agropyron cristatum [L] Gaertm) has been seeded on more than 5 million hectares in western North America because it establishes more readily than native bunchgrasses. Currently, there is substantial interest in reestablishing native species in sagebrush steppe, but efforts to reintroduce native grasses into crested wheatgrass stands have been largely unsuccessful, and little is known about the long-term dynamics of crested wheatgrass/native species mixes. We examined the abundance of crested wheatgrass and seven native sagebrush steppe bunchgrasses planted concurrently at equal low densities in nongrazed and unburned plots. Thirteen years post establishment, crested wheatgrass was the dominant bunchgrass, with a 10-fold increase in density. Idaho fescue (Festuca idahoensis Elmer), Thurber’s needlegrass (Achnatherum thurberianum (Piper) Barkworth), basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Löve), and Sandberg bluegrass (Poa secunda J. Presl) maintained their low planting density, whereas bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve), needle-and-thread (Hesperostipa comata [Trin. & Rupr.] Barkworth), and squirreltail (Elymus elymoides [Raf.] Swezey) densities declined. Our results suggest that densities of native bunchgrasses planted with crested wheatgrass are unlikely to increase and that some species may only persist at low levels. The high recruitment of crested wheatgrass suggests that coplanting of some native bunchgrasses may be a viable way of avoiding crested wheatgrass monocultures when this species is necessary for rehabilitation or restoration.

Prescribed fire is commonly applied world-wide as a tool for enhancing habitats and altering resource-selection patterns of grazing animals. A scientific basis for this practice has been established in some ecosystems but its efficacy has not been rigorously evaluated on mesic sagebrush steppe. Beginning in 2003, resource-selection patterns of beef cows were investigated using global positioning system (GPS) collars for 2 years before and for 5 years after a fall prescribed burn was applied to mesic sagebrush steppe in the Owyhee Mountains of southwestern Idaho, USA. Resource-selection functions (RSF) developed from these data indicated cattle selected for lightly to moderately burned areas for all 5 postfire years. Cattle had been neutral towards these areas prior to the fire when their distribution was primarily affected by slope, sagebrush dominance, and distance to upland water. Resource-selection responses to the fire lasted 2–3 years longer than would be expected for fire-induced, forage-quality improvement effects. Although this is a case study and caution should be taken in extrapolating these results, if applied under conditions similar to this study, livestock producers and natural resource managers can likely use fall prescribed fire in the mesic sagebrush steppe to affect cattle resource-use patterns for 5 years postfire.

On rangelands, uneven or unmanaged livestock distribution can adversely affect plant community composition, riparian function, or displace wildlife. These issues have historic precedents and are still a challenge for those managing rangelands. A thorough understanding of the mechanisms governing livestock distribution can help land and livestock managers avoid or ameliorate many deleterious effects. To that end, this research tested hypotheses that grazing cattle seek nutritionally superior portions of rangeland pastures. Global positioning system (GPS) collars were used to track cattle movement and activity in three, 800+ha pastures where the spatial distribution of standing crop, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and forage digestibility (in situ dry matter disappearance (ISDMD)) were mapped in late spring. Four of five analyses implied grazing cattle spatially responded to forage quantity/quality attributes. Analyses indicated cattle favored higher than average CP (P=0.006) and ISDMD (P=0.078), and lower than average NDF (P=0.003) and standing crop (P=0.069) locales. No significant effect (P=0.954) occurred with ADF analyses. Correlations among those variables imply cattle may simultaneously respond to more than one nutritional attribute as they select foraging locales. Stepwise regression, however, relating grazing distribution to geophysical and forage quantity/quality characteristics were extremely poor predictors of where cattle grazed. Listed in order of entry, the model implied elevation above or below stock water, horizontal distance to stock water, forage CP content, and degree of slope were the site specific attributes most associated with cattle distribution. We speculate that cattle interactions with landscape level nutritional dynamics may at least partially explain seasonal changes in distribution and forage use by cattle across the landscape. These findings should help land and livestock managers understand, explain, and manipulate livestock distribution on their holdings.

A challenge in animal behavior studies using Global Positioning System (GPS) collars is selecting a sampling frequency to accomplish desired goals. High data resolution (i.e., frequent sampling) is appealing, because it maximizes behavioral information garnered. Extended sampling might be needed, however, to describe long term behaviors or seasonal dynamics. Because tradeoffs exist between high data resolution and sampling duration, we evaluated the effects of variable GPS sampling intervals on proportions of pastures used by cattle and distance traveled per day. This was accomplished with GPS collars configured to record cattle positions every 5 min for 15 d in three 829-864-ha pastures. Data were iteratively reduced to simulate increasingly longer GPS recording intervals from once every 10 min up to once daily. Two techniques were used to measure the percentage of pastures accessed by cattle. The first counted only pixels containing GPS coordinates. The second counted pixels containing coordinates and/or traversed by lines between vertices. Expansion of GPS recording intervals decreased (P < 0.01) estimates of the proportion of pastures visited by cattle with rates of decline best fit by exponential decay functions for both line and point techniques (R-2 = 0.93 and 0.97, respectively). Spatial errors accompanying less frequent sampling intervals, however, were extremely large with the line technique and misrepresented areas visited by cattle. Expansion of GPS sampling intervals decreased (P < 0.001) distance traveled per day by cattle about 10% with each iteration. If travel corridors or accurate assessments of resources accessed are of critical concern, then longer GPS integration intervals should be avoided because they propagate flawed spatial interpretations. Similarly, if accurate measures of travel distances are critical, we suggest using a relatively frequent GPS recording interval.

MELVIN GEORGE, Extension Rangeland Management Specialist, Department of Plant Sciences, University of California, Davis; DEREK BAILEY, Associate Professor, Department of Animal and Range Sciences, New Mexico State University, Las Cruces; MICHAEL BORMAN, Professor and Extension Rangeland Ecology and Management Specialist, Department of Rangeland Ecology and Management, Oregon State University, Corvallis; DAVID GANSKOPP, Rangeland Scientist, USDA Agricultural Research Service, Eastern Oregon Agricultural Research Center, Burns; GENE SURBER, Extension Natural Resources Specialist, Department of Animal and Range Sciences, Montana State University, Bozeman; and NORM HARRIS, Assistant Professor, School of Natural Resources and Agricultural Sciences, University of Alaska, Fairbanks

Global Positioning System (GPS) error, associated with free-ranging animal studies, remains a concern in range/animal research. For distance measures, errors may be additive over time and increase as sampling frequency intensifies. The first study assayed effects of coordinate integration time (10 hourly intervals), 10 GPS collars, and range of unit movement (0 to 90 m in 10-m intervals as treatments) on bias of GPS measures of distance. "Bias" was the difference between measured distances and distances derived from GPS coordinates of units moved over a surveyed grid. A second study evaluated four methods (regression modeling, minimum distance threshold, motion sensor threshold, and a combined minimum distance/motion sensor technique) for extracting perceived movements from GPS data acquired from cattle. A classification assessment compared observation data of cattle with their corresponding GPS records after filtering by the four techniques. Except for immobile GPS collars in study 1, bias of distance measures was inconsequential for movements ranging from 10 to 90 m (differentially corrected mean bias = 0.18 m +/- 0.12 m SE). When collars were immobile, GPS error generated about 1.7 m +/- 0.7 in SE of perceived travel per record with postdifferentially corrected coordinates (P < 0.05), and 3.9 m +/- 0.8 m SE with uncorrected data. At specific times, post-differential correction failures can affect (P <= 0.05) GPS measures of distance. Using any of four proposed techniques, one may effectively filter data sets to remove perceived travel accrued when cattle were resting with 81% to 92% of resting intervals correctly classified. The most effective regression technique suggested cattle travels were overestimated by about 15.2% or 1.15 km daily without filtering.

Thurber needlegrass (S@r tiwrbericuro Piper) is an important component of both forested and shrub-steppe communities of the Pacific Northwest and Great Basin regions, and little is known of its tolerance to defoliation. A study was conducted on the !Squaw Butte Experimental Range to determine the response of containerized Thurber needlegrass to single defoliations (2Scm stubble) throughout the growing season. Dates of treatment spanned vegetative through quiescent stages of phenology. Response variablea included: summer regrowth, number of reproductive stems, fall growth, and subsequent spring herbrp production, change in basal area, and root mass. Vigor of Thurber needlegrass was reduced most by defoliation during the early-boot stage of development. Impacts were successively leas severe from vegetative, I&-boot, and anthesis treatments, respectively. Cumulative herbage production the year of treatment was reduced from 38 to 64% by defoliation at the early-boot stage. The same treatment reduced subsequent spring growth by 46 to 51% and root mass the next spring by 34 to 45%. Treatment effects were somewhat reduced when temperature and moisture regime-s allowed substantial regrowth after defoliation. Defoliation during or after anthesis had little effect on plant response. Managers should be aware that a single defoliation, particularly during the boot stage, can significantly reduce subsequent herbage production and root mass and possibly lower the competitive ability of Thurber needlegrass.

In the growing season following a severe one-year drought in central and eastern Oregon (precipitation 49% of average), various parameters of individual ungrazed and grazed plants of bluebunch wheatgrass, Idaho fescue, Thurber needlegrass, and crested wheatgrass at 11 locations were evaluated. An average of 43% aboveaverage precipitation occurred during the study growing season. Lightly grazed Idaho fescue and bluebunch wheatgrass produced as much, and in some cases, more height growth, final weight, and seed stalks than ungrazed plants. No differences occurred between moderately grazed and ungrazed bluebunch wheatgrass and Idaho fescue. Moderately grazed crested wheatgrass produced similarly to ungrazed plants but started growth more slowly. Grazing heavier than 70% reduced production and height of Idaho fescue and Thurber needlegrass but did not significantly impact bluebunch wheatgrass. No plant mortality occurred regardless of past grazing