Raul Valdez

Raul Valdez
New Mexico State University | NMSU · Department of Fish, Wildlife and Conservation Ecology

Ph.D.

About

124
Publications
56,592
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2,043
Citations
Citations since 2016
32 Research Items
821 Citations
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120

Publications

Publications (124)
Article
Full-text available
Our study evaluated the effectiveness of using eight pathways in combination for a complete to transition from fossil fuels to renewable energy by 2050. These pathways included renewable energy development; improving energy efficiency; increasing energy conservation; carbon taxes; more equitable balancing of human wellbeing and per capita energy us...
Article
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Wild sheep ( Ovis spp.) are of conservation concern throughout the Middle East. Little is known, however, about the natural history or ecology of this taxon. To better understand size relationships among wild sheep occupying Iran, we analyzed results from 120 females collected from widely separated ecosystems. Morphometrics and body weights for all...
Article
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Aim: Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroeco...
Article
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We investigated the effects of climate change on the distribution of the Asiatic ibex (Capra sibirica) in eastern Tajikistan. No existing climate change studies have been conducted on the habitat of a wild goat species in Asia. We conducted ecological niche modelling to compare potential present and future distributions of suitable environmental co...
Article
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In arid ecosystems, desert bighorn sheep are dependent on natural waterholes, particularly in summer when forage is scarce and environmental temperatures are high. To detect waterholes in Sierra Santa Isabel, which is the largest area of desert bighorn sheep habitat in the state of Baja California, Mexico, we used the normalized difference vegetati...
Data
Excel spreadsheet with database of terrain escape from VRM. (XLSX)
Data
Records of wildlife in the waterholes. (PDF)
Data
Excel spreadsheet with database of NDWI from Sentinel-2. (XLSX)
Data
Excel spreadsheet with database of NDVI from Sentinel-2. (XLSX)
Data
Flowchart representing the processing of satellite images and calculations of the NDVI and NDWI. (TIF)
Data
Plants identified at the periphery of waterholes detected in the Sierra Santa Isabel, Baja California. (PDF)
Article
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Identifying the factors predicting the high‐elevation suitable habitats of Central Asian argali wild sheep and how these suitable habitats are affected by the changing climate regimes could help address conservation and management efforts and identify future critical habitat for the species in eastern Tajikistan. This study used environmental niche...
Article
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Our objective was to assess the status of the large native rangeland mammals in the eastern and southern African countries focusing on conservation strategies that will benefit the animals, their rangeland habitats, and the people who live in this region. Eastern and southern African rangelands are renowned for supporting a globally unique diversit...
Article
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We modeled summer and winter habitat suitability of Marco Polo argali in the Pamir Mountains in southeastern Tajikistan using these statistical algorithms: Generalized Linear Model, Random Forest, Boosted Regression Tree, Maxent, and Multivariate Adaptive Regression Splines. Using sheep occurrence data collected from 2009 to 2015 and a set of selec...
Preprint
Full-text available
The desert bighorn sheep is adapted to the extreme conditions of arid ecosystems. The amount and distribution of watering holes is an essential component of the habitat of this species. With information provided by people in Sierra Santa Isabel a database of potential sites watering sites was obtained, which was taken as reference of spectral infor...
Preprint
Full-text available
The desert bighorn sheep is adapted to the extreme conditions of arid ecosystems. The amount and distribution of watering holes is an essential component of the habitat of this species. With information provided by people in Sierra Santa Isabel a database of potential sites watering sites was obtained, which was taken as reference of spectral infor...
Conference Paper
Las selvas tropicales son áreas importantes para la conservación de especies, sin embargo, más de medio millón de hectáreas no se consideran bajo ninguna categoría de protección por lo que han sido seriamente perturbadas afectando a toda la biodiversidad que ahí habita. Este estudio tuvo como objetivo determinar la riqueza, diversidad de mamíferos...
Conference Paper
El venado cola blanca es la especie cinegética más aprovechada en México, de tal manera que el conocimiento detallado de la población en una Unidad de Manejo se hace indispensable para lograr un aprovechamiento sustentable. La proporción de sexos y clases de edad son índices que permiten conocer el estado de la población y la calidad del hábitat, a...
Article
Aims Recognizing ungulate browsing thresholds between viable and declining aspen (Populus tremuloides Michx.) stands are critical to ensuring long-term persistence of this biologically important plant community. Studies have shown declines in vigor and regeneration when as few as 30% of current annual twigs are browsed while other studies have show...
Article
Seven Geographic Information System (GIS) layers comprise this dataset intended for understanding the Marco Polo argali habitat in the southeastern Tajikistan Pamirs (37 ˝ 33 1 N, 74 ˝ 09 1 E). Extensive remote sensing habitat data processing and field data analysis of the Marco Polo sheep study area have yielded these layers that are now available...
Article
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We tested the Moment Distance Index (MDI) in combination with texture features for the summer vegetation mapping in the eastern Pamir Mountains, Tajikistan using the 2014 Landsat OLI (Operational Land Imager) image. The five major classes identified were sparse vegetation, medium-dense vegetation, dense vegetation, barren land, and water bodies. By...
Article
Marco Polo sheep (Ovis ammon polii), listed as Near Threatened in the IUCN Red List, were surveyed using vehicles during three summers and three consecutive winters to determine the status and population structure of the subspecies in a hunted population in southeastern Pamirs, Tajikistan. A total of 8649, 8392, and 7663 sheep were observed in each...
Article
Full-text available
Water used by bighorn sheep during the 2011 and 2013 dry seasons and the rainy season and drought of 2015 in the Sierra Santa Isabel of the State of Baja California, Mexico was analyzed for seven physicochemical parameters. At four watering sites, 260 photographs of sheep were obtained. Females, yearlings, and lambs accounted for 73% of the photogr...
Article
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We described in this report the essential geographic layers used as landscape drivers for the Marco Polo Argali habitat in the eastern Tajik Pamirs. Using remote sensing techniques and geographic information systems (GIS), individual layers were generated in order to acquire more information on argali patterns and habitat suitability and to make th...
Article
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Introduction: Escape terrain and vegetation cover are two vital components in bighorn sheep habitat use. Understanding these components is essential for conserving and managing this species. Despite the importance of assessing habitat use, there are few studies in Mexico and most efforts have focused on population surveys. The lack of studies of bi...
Article
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INTRODUCCIÓN: El terreno de escape y la cobertura vegetal son dos componentes vitales en el hábitat del borrego cimarrón. La evaluación de la selección que hacen los borregos cimarrones de estos componentes es fundamental para determinar su distribución y el número de organismos que puede soportar un área. A pesar de la importancia de evaluar la se...
Article
Full-text available
Marco Polo sheep (Ovis ammon polii), listed as Near Threatened in the IUCN Red List, were surveyed using vehicles during three summers and three consecutive winters to determine the status and population structure of the subspecies in a hunted population in southeastern Pamirs, Tajikistan. A total of 8649, 8392, and 7663 sheep were observed in each...
Article
Full-text available
Marco Polo sheep (Ovis ammon polii), listed as Near Threatened in the IUCN Red List, were surveyed using vehicles during three summers and three consecutive winters to determine the status and population structure of the subspecies in a hunted population in southeastern Pamirs, Tajikistan. A total of 8649, 8392, and 7663 sheep were observed in each...
Article
Full-text available
Resumen The habitat of the neotropical otter (Lontra longicaudis) at La Vega Escondida Protected Area (LVPA), located in southern Tamaulipas, is surrounded by an expanding urban landscape. Wetlands in this region are under an intense pressure due to several anthropogenic activities such as agriculture, livestock and commercial fisheries. The main g...
Article
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Two techniques frequently used for monitoring pronghorn populations were compared in vegetation communities of the Chihuahuan Desert in New Mexico, USA. The evaluated techniques included the walking line transect and the driving line transect under two vegetation types and relative to season. The true population value (control) used to evaluate the...
Article
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The northernmost known breeding population of jaguars occurs in the municipality of Nácori Chico, Sonora, Mexico about 270 km from the United States-Mexico border and may be the source from which jaguars sighted in the United States dispersed. Since 1999 at least 11 jaguars (Panthera onca) had been illegally killed in the area due to predator contr...
Article
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Predation on cattle by the endangered jaguar (Panthera onca) can be a serious ecological and economic conflict. We investigated habitat characteristics of kill sites of cattle in Sonora, Mexico, from 1999 to 2004 to see whether habitat management or cattle distribution could be used as effective nonlethal methods to limit predation. Kill-sites were...
Article
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The effects of large ungulate herbivory on plant community structure and composition can vary considerably in regions susceptible to frequent wildfires. The Cerro Grande Fire (CGF) of May 2000 burned 17,400 ha of elk transitory-use range in the Jemez Mountains, north-central New Mexico. Our objective was to determine if habitat use changed temporal...
Article
Las densidades de “Mourning dove” (Zenaida macroura L.) fueron determinadas en potreros de condición ecológica es estado seral inicial, medio y final durante un período de dos años (primavera de 1996 e invierno de 1998) y para ello se usaron técnicas de censo en bandas. El estudio se condujo en el Centro de Investigación de Pastizales del Desierto...
Article
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A study was conducted to evaluate the influence of good (GC) and fair (FC) range condition classes on pronghorn and cattle diets. There was a higher preference for the GC (84%) than for the FC (16%) area (P<0.05). Pronghorn in GC consumed maximum shrubs (51.8%) followed by grasses (29.9%) and forbs (18.3%). In FC the sequence was the same but for t...
Article
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Mexico's wildlife has been impacted by human land use changes and socioeconomic and political factors since before the Spanish conquest in 1521. Presently, it has been estimated that more than 60% of the land area has been severely degraded. Mexico ranks in the top 3 countries in biodiversity, is a plant and faunal dispersal corridor, and is a cruc...
Article
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 northeaste...
Article
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 o...
Article
Hispanics are a growing segment of the United States population and will be an increas- ingly important stakeholder in future allocation and management of natural resources, including wildlife. In the United States, Hispanics now are the largest ethnic minority and will remain so over the next 40 years. Texas supports the second-largest Hispanic po...
Article
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The nutritional carrying capacity for Montezuma quail (Cyrtonyx montezumae) was estimated during winter and spring. The biomass availability of bulbs of Oxalis in Aculco municipality, Mexico state was measured in transitional zones of pine forested areas and rangelands by quantification of Oxalis bulbs (5 cm). Intake was estimated using energy requ...
Article
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The northern Aplomado Falcon (Falco femoralis septentrionalis) historically occupied coastal prairies, savannas, and desert grasslands from southern Mexico north to southern and southwestern Texas, southern New Mexico, and southeastern Arizona. Current resident Aplomado Falcon populations are primarily in Mexico, with isolated populations in southe...
Article
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Exotic wildlife can introduce new diseases or act as reservoirs of endemic diseases. On White Sands Missile Range, New Mexico (USA), significant declines in populations of native ungulates generally correspond to increases in range and population density of the exotic gemsbok (Oryx gazella gazella), introduced beginning in 1969. We surveyed gemsbok...
Article
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Scaled quail (Callipepla squamata) numbers were evaluated during and after a 2-year drought period using strip census techniques on 2 pastures in late seral rangeland ecological condition and 2 pastures in mid-seral rangeland ecological condtion. This study was conducted on the Chihuahuan Desert Rangeland Research Center (CDRRC) in south-central Ne...
Article
It is questionable whether food-habits studies of pumas conducted in the southwestern United States can be extrapolated to northwestern Mexico, because of differences in management, distribution, and abundance of wildlife. We determined food habits of pumas (Puma concolor) in the Sonoran Desert of northwestern Sonora, Mexico. Based on studies in th...
Article
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Seasonal wildlife observations were made along transects on 2 pastures conservatively grazed (36% use of perennial grasses) and 2 pastures moderately grazed (47% use of perennial grasses) in south central New Mexico in non-drought (1997) and drought years (1998). Experimental pastures were similar in soils, terrain, spacing of watering points, and...
Article
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The use of habitat components by desert bighorn sheep ( Ovis canadensis ) was examined to explain sexual segregation of sheep in Sierra el Viejo, Sonora, Mexico. We evaluated 265 plots used by bighorns and 278 random plots from April 1997 to December 1998. Groups of segregated males and females preferred the elephant tree ( Bursera microphylla )-sa...
Article
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We used microhistological analyses of fresh fecal pellets to determine seasonal diets of desert bighorn sheep (Ovis canadensis mexicana Merriam 1901) in northwestern Sonora, Mexico from April 1997 to December 1998. We identified 41 plant species (22 browse, 10 forbs, 5 grasses, and 4 succulents) in diets of bighorn sheep. We found no differences be...
Article
Short-duration grazing reduced individual cattle productivity in some of the African studies due to stress from heavy stocking and movement of cattle from one paddock to another. Some increase in stocking is possible with short-duration grazing compared to more simplistic systems because multi-paddocks improve livestock distribution. Gammon (1984)...
Article
Mourning Doves are the most commonly hunted game bird in New Mexico based on hunter harvest data collected by New Mexico Department of Game and Fish. Research is limited on the influence of rangeland ecological condition on Mourning Dove (Zenaida macroura) populations in the Chihuahuan Desert of New Mexico. Mourning Dove numbers were evaluated peri...
Article
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During the 1980's short-duration grazing attracted much attention based on the claims it would accelerate range improvement while at the same time accommodating higher stocking rates. On many ranches it was contended that stocking rates could be doubled or even tripled while at the same time improving both range and livestock productivity. We will...
Article
Dalai-lamae (Ovis ammon dalai-lamae), Gobi (O. a. darwini), Kara Tau (O. a. nigrimontana) and Tibetan (O. a. hodgsoni) argali share a 2n = 56 diploid chromosome number and a karyotype consisting of 2 pairs of biarmed and 25 pairs of acrocentric autosomes, a large acrocentric X and a minute Y chromosome. The Giemsa-banding patterns of the largest pa...
Article
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From February to June 1996, we observed breeding numbers, chronology, nest characteristics, and productivity of Yellow-footed Gulls (Larus livens) on and near Isla del Carmen, Baja California Sur, Mexico. Of 124 active nests on Isla del Carmen, 75.8% were single or in groups of ≤ ten nests. Most nests observed were 1.5-10 m above high tide line on...
Article
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The information is presented on the independent state of Turkmenistan as a rich depository of unique biodiversity. Biodiversity in Turkmenistan is well-studied compared to many adjacent areas due to the unique historical and political circumstances. The long and complicated geological history of Turkmenistan has provided a diverse arena for the for...
Article
The Chihuahuan Desert of the southwestern United States and northern Mexico is the primary habitat of the scaled quail (Callipepla squamata), but populations have declined over much of this area since 1960. Because changes in ecological condition of Chihuahuan Desert rangelands may explain the decline in scaled quail populations over the last 37 ye...
Article
We estimated density and characterized roosting habitat of Mexican Spotted Owls (Strix occidentalis lucida) in the Sierra Madre Occidental in southwestern Chihuahua, Mexico. Mean Spotted Owl density in Chihuahua (0.089 owls km-2) was approximately half that reported for Arizona and New Mexico. Owls were primarily (70%) roosting in medium-sized tree...
Article
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Botanical diet composition of pronghorn (Antilocapra americana), gemsbok (Oryx gazella), and feral horses (Equus caballus) on White Sands Missile Range, New Mexico, was determined using fecal analysis. Pronghorn diets consisted of 58% shrubs, 20% grasses, 17% forbs, and 5% unknowns. Gemsbok diets consisted of 83% grasses, 16% shrubs, and <1% forbs...
Article
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We analyzed pellets of Mexican Spotted Owls (Strix occidentalis lucida) collected at roost and nest sites in Chihuahua from 1992-94, and Aguascalientes, Mexico from 1994-95 to determine diet composition. We identified 647 prey items from 13 owl territories iii Chihuahua and four owl territories in Aguascalientes. Vertebrates constituted 64% of all...
Article
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Seasonal wildlife observations were made along transects on 2 pastures in late seral and 2 pastures in mid seral condition in southcentral New Mexico in non-drought and drought years (1993, 1994). Remaining climax vegetation was about 64% and 57% on late seral pastures. About 37% and 32% of the climax vegetation remained on mid seral pastures. Tota...
Article
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We observed 227 Heptner's markhors (Capra falconeri heptneri) during a survey of this endangered subspecies in April 1995 in the Kugitang Nature Reserve of eastern Turkmenistan. Because of the Limited area surveyed, this census provided a minimal estimate of the size of the population. The population appears Po be increasing, which is due to remova...