• Change on the Range...Mongolian Style

      Frisina, Michael R.; Valdez, Raul (Society for Range Management, 1994-08-01)
    • Elk and Mule Deer Diets in North-Central New Mexico

      Sandoval, Leonard; Holechek, Jerry; Biggs, James; Valdez, Raul; VanLeeuwen, Dawn (Society for Range Management, 2005-07-01)
      Botanical composition of mule deer and elk diets in winter, spring, summer, and autumn was studied during 1998 and 1999 on woodland rangeland in north-central New Mexico using microhistological analysis of fecal samples. Our study area had no livestock grazing for 60 years but was moderately grazed by mule deer and elk. Elk and mule deer shared 3 of the top 5 key forage species when diets were pooled across seasons and years. These 3 species were oak (Quercus sp.), ponderosa pine (Pinus ponderosa Dougl.), and mullein (Verbascum thapsus L.). When data were pooled across seasons and years, overall dietary overlap between mule deer and elk was 64%. Diet overlaps of 50% or more occurred between mule deer and elk in all 4 seasons in both years of study. Throughout both years, mule deer and elk diets were dominated by browse. Mountain mahogany (Cercocarpus montanus Raf.) was the most abundant browse plant in mule deer diets; ponderosa pine was most abundant in elk diets. Both animals selected forbs, which were in low supply during the study. Scarlet globemallow (Sphaeralcea coccinea Pursh), a nutritious forb, was common in both mule deer and elk diets. Our study and others from woodland rangelands in New Mexico show high potential for forage competition between mule deer and elk. Elk are more dietarily adaptable to changing forage availability than are mule deer. Our study indicates that diets of mule deer and elk are not complementary on woodland rangelands in New Mexico. Therefore, grazing capacity is not increased by common-use grazing of the 2 animals. Both mule deer and elk herds have been increasing on our study area. Therefore, if use of common forage species is kept at moderate levels on southwestern woodland rangelands, mule deer herds can be maintained or increased when elk are present.  
    • Influence of native shrubs on nutritional status of goats: nitrogen retention

      Nunez-Hernandez, Gregorio; Holecheck, Jerry L.; Wallace, Joe D.; Galyean, Michael L.; Tembo, Ackim; Valdez, Raul; Cardenas, Manuel (Society for Range Management, 1989-05-01)
      In vivo digestibility trials were conducted to evaluate the influence of shrubs containing low and high levels of soluble phenolic/-tannins on digestibility and nitrogen retention by Angora goats. Each of 6 shrubs and alfalfa hay (Medicago sativa L.) were fed to goats at 30% (dry matter basis) of the diet in a barley straw-prairie hay mixture. The mixture was regulated so that all diets contained about 8% crude protein. High soluble phenolic shrubs used included big sagebrush (Artemisia tridentata Nutt. ssp. tridentata), gray oak (Quercus grisea Liebm.), true mountain mahogany (Cercocarpus montanus Raf.), and one-seed juniper (Juniperus monosperma [Engelm.] Sarg). Low-soluble phenolic species included common winterfat (Ceratoides lanata [Pursh.], J.T. Howell), fourwing saltbush (Atriplex canescens [Pursh.], Nutt.), and alfalfa. Nitrogen digestibilities of winterfat, gray oak, mountain mahogany and one-seed juniper diets were less (P<.05) than the alfalfa controls, but big sagebrush did not differ (P>.05) compared with the alfalfa control. Retained nitrogen (g/d) differed (P<.05) only among alfalfa, juniper, and mountain mahogany diets. Goats fed juniper had greater (P<0.05) retained nitrogen than the alfalfa control. Shrubs high in soluble phenolics, with the exception of big sagebrush, had elevated fecal nitrogen losses, but reduced urinary nitrogen losses compared with the alfalfa control. Forage organic matter intake (% body weight) and nitrogen intake (g/d) were correlated more highly with nitrogen retention than dietary crude protein (%) or digestible protein (%). Present data indicate that protein found in palatable native shrubs is assimilated with similar efficiency to that in alfalfa hay if these shrubs are consumed at moderate levels.
    • Jaguar and Puma Predation on Cattle Calves in Northeastern Sonora, Mexico

      Rosas-Rosas, Octavio C.; Bender, Louis C.; Valdez, Raul (Society for Range Management, 2008-09-01)
      Predation by jaguars (Panthera onca) and pumas (Puma concolor) is often a source of conflict with cattle ranching in northeastern Sonora, Mexico. Because jaguars are endangered in Mexico, such conflicts have biological, social, and economic consequences. We documented the extent of predation by jaguars and pumas on cattle in 1999-2004 in northeastern Sonora, where the northernmost breeding population of jaguars exists in North America. Jaguars and pumas killed only calves , 12 mo old, and calves constituted 58% of prey biomass consumed by jaguars and 9% by pumas. Annual cause-specific mortality rates of confirmed jaguar predation (< 0.018), confirmed and suspected jaguar predation (< 0.018), and all confirmed and suspected large felid predation (< 0.018) were low and cattle calf survival was high (0.89-0.98 annually). If calves reported as missing but for which no evidence of mortality could be found were classed as large felid predation, annual cause-specific rates increased to 0.006-0.038. Collectively, confirmed jaguar and puma predation accounted for < 14% (57/408) of total cattle losses, with jaguars responsible for 14% of all calf losses; this could increase to a maximum of 36% (146/408) if missing calves were included in the totals. While jaguar and puma predation may have an impact on some small cattle operations, it is generally minor compared to losses from other causes in northeastern Sonora. Moreover, 91% of all confirmed calf kills were associated with three individual jaguars in our study. Targeting problem cats rather than broad-scale predator control may therefore be a viable alternative to address chronic predation problems. Because most (83%) instances of jaguar predation occurred during the dry season along thick riparian habitats, modified cattle husbandry operations, such as establishment of permanent water sources in uplands and away from dense vegetative cover, could ameliorate many cases of predation by jaguars on cattle. 
    • Mourning dove densities on Chihuahuan Desert rangelands

      Joseph, Jamus; Holechek, Jerry L.; Valdez, Raul; Thomas, Milt (Society for Range Management, 2004-05-01)
      Mourning dove (Zenaida macroura L.) densities were determined using strip census techniques over a 2-year period (spring 1996 to winter 1998) on pastures in early-, mid-, and late-seral ecological condition. This study was conducted on the Chihuahuan Desert Rangeland Research Center and adjacent Bureau of Land Management rangelands in south-central New Mexico on 6 adjoining pastures that were similar in terrain and shape. Mourning dove densities pooled across sampling periods (8) were different (P < 0.10) on pastures in mid- and early-seral condition. They averaged 10.3, 33.9, and 7.2 birds km-2 on pastures in late-, mid- and early-seral condition, respectively. Leatherleaf croton (Croton pottsii Lam.), the primary mourning dove food on all study pastures, was more abundant (P 0.10) on late- and mid-seral pastures than on early-seral pastures. Therefore, heavy livestock grazing may adversely affect mourning dove populations in the Chihuahuan Desert by depleting leatherleaf croton. Autumn perennial grass cover and standing biomass differed (P < 0.10) among seral stages. More optimal interspersion of bare ground and perennial grasses may further explain why mid-seral rangelands tend to favor mourning doves. Our study shows mourning doves in the Chihuahuan Desert prefer moderately grazed, mid-seral rangelands over heavily grazed, early-seral rangelands.
    • Short Duration Grazing Research in Africa: An extensive review of the Charter Grazing Trails and other short duration grazing studies on African rangelands

      Joseph, Jamus; Molinar, Francisco; Galt, Dee; Valdez, Raul; Holechek, Jerry (Society for Range Management, 2002-08-01)
    • Short-Duration Grazing: The Facts in 1999

      Holechek, Jerry L.; de Souza Gomes, Hilton; Molinar, Francisco; Galt, Dee; Valdez, Raul (Society for Range Management, 2000-02-01)
    • Stocking rate effects on goats: A research observation

      Mellado, Miguel; Valdez, Raul; Lara, Laura M.; Lopez, Ramiro (Society for Range Management, 2003-03-01)
      Knowledge on the ecological effects of goat grazing on arid rangeland is far from complete, and specifically there is little scientific information on effects of heavy goat grazing on arid ecosystems. One objective of this study was to determine botanical composition of dairy-type goat diets on heavily (1.5 ha per goat) and lightly (15 ha per goat) grazed Chihuahuan desert range by fecal microhistological analysis. A second objective was to determine whether vegetation cover, some blood metabolites and mineral levels, as well as fertility of goats were sensitive to high grazing pressure. The lightly grazed site had more (P < 0.05) total foliage cover (38.6 vs 30.4%) than the overstocked pasture. Total shrubs in diets of goats was greater (86.4 vs 72.4 in the late-dry period, 78.6 vs 42.1 in late-wet period; P < 0.05) on the heavily stocked pasture than the lightly stocked pasture. Forbs in the diets were lower (P < 0.10) in the late-dry (11.4 vs 21.5%), early-wet (55.4 vs 64.0%) and late-wet period (15.0 vs 45.8%) on the heavily stocked pasture than the lightly stocked pasture. Substantially lower (P < 0.01) serum glucose, urea nitrogen, Zn and Mg concentration at the onset of the breeding period in goats on the heavily stocked pasture, compared to goats on the lightly grazed pasture resulted in a higher (P < 0.01) abortion rate (22 vs 12%) and consequently a lower (P < 0.05) kidding rate (42 vs 55%). We concluded that overstocking with goats greatly reduced shrub and grass cover. Also, decades of continuously high grazing pressure has forced goats to alter diet selection pattern by consuming more resinous, toxic, and coarse species. This switch was associated with a lower nutritional status, a negative daily weight gain, lower body condition score in the late-wet period, and lower fertility on heavily grazed range.
    • Wildlife Plant Community Preference in the Chihuahuan Desert

      Nelson, Terry; Holechek, Jerry; Valdez, Raul (Society for Range Management, 1999-01-01)