No abstract

No abstract

Desert ungulates must contend with high solar radiation, high ambient temperatures, a lack of water and cover, unpredictable food resources, and the challenges these factors present for thermoregulation and water balance. To deal with the conflicting challenges of maintaining body temperature within acceptable limits and minimizing water loss, desert ungulates use a variety of physiological, morphological, and behavioral mechanisms. The mechanisms involved in thermoregulation and water balance have been studied in many domestic and wild African and Middle Eastern ungulates; studies involving ungulates inhabiting North American deserts are limited in comparison. Our objectives were to review available scientific literature on thermoregulation, water balance, and the effects of dehydration in desert ungulates. We discuss the physiological, morphological, and behavioral mechanisms used by ungulates to maintain temperature and water balance in arid environments, and the implications for research and management of desert ungulates in western North America.

Topography, vegetation, and animal behavior may influence the performance of Global Positioning System (GPS) telemetry collars, affecting fix success rates and location error. We reviewed the scientific literature published from 1995 to June 2004 to determine the fix intervals used and fix success rates obtained in studies using GPS telemetry. We also programmed GPS telemetry collars with 6 different fix intervals and placed them at fixed locations of varying topography in the Cabeza Prieta National Wildlife Refuge, Arizona from August 2003‐May 2004. Fix interval affected fix success rates both in our field study (99, 98, 96, 94, 93, 92% fix success rate for 0.25, 0.5, 1, 4, 6, and 13‐hour fix intervals, respectively) and in our analysis of data obtained from scientific literature (r2=0.531, P ≤ 0.001), with shorter fix intervals being associated with higher fix success rates. Topography affected the fix success rate (F2, 77=12.017, P ≤ 0.001), location error (F2, 77=6.76, P=0.002), and proportion of 3‐dimensional (3‐D) fixes (F2, 77=10.184, P ≤ 0.001), resulting in lower fix success rates and larger location errors in areas with more rugged topography. The influence of topography and fix interval on location error and fix success rates may bias GPS location data, resulting in misclassification of habitat use and under‐sampling certain areas used by animals. Location error and missing data can increase type II error and may result in incorrect inferences in some studies. These biases need to be assessed and steps should be taken to minimize their influence on results of studies of habitat selection and other aspects of animal ecology.

No abstract

No abstract

Social construction is the virtue ascribed to a subject by the general public; along with political power, it influences the allocation of public policy benefits. Nonhuman species are socially constructed by humans, and political power is held in trust for them by human interest groups. Our goal was to determine if the allocation of benefits to endangered species is consistent with social construction and political power. We assessed the social construction of broad types of species using survey data collected from a national sample of 643 respondents. We found that plants, birds, mammals, and fish have a distinctly more positive social construction than reptiles, amphibians, invertebrates, and microorganisms. Respondents also indicated, however, that all nonhuman species should be conserved and that ecological importance and rarity are the most important factors to consider in prioritizing species for conservation. We gauged the political power affiliated with types of species by the number of nongovernmental organizations representing them. Birds have a substantial advantage over all other types. We employed a political science model that identifies policy subjects based on social construction and political power and identified birds, mammals, and fish as “advantaged” subjects, plants as “dependents,” and reptiles, amphibians, invertebrates, and microorganisms as “deviants.” Numerous exceptions, especially among mammals, are best described as “contenders.” Allocation of the benefits of the U.S. Endangered Species Act is consistent with predictions of the model. A myriad of values converge to favor birds, mammals, fish, and plants in the policy arena. The most promising opportunities for species conservation in the political arena, however, may be with plants and amphibians, for which the ratio of social construction to benefit allocation is highest.
Opinión Pública, Poder Politico, y Ubiación de Beneficios para Especies Amenazadas
La opinión pública y el poder político influencian la distribución de beneficios hacia los sujetos humano de la política. La opinión pública sobre especies no humanas está también determinada por el ser humanos, y el poder político asociado a estas especies se ejerce a través de grupos interesados en ellas. Nuestro objetivo fue determinar si la distribución de beneficios dirigidos a especies en peligro de extinción es consecuente con la opinión pública y el poder político. Realizamos una evaluación de la opinión pública sobre grupos amplios de tipos de especies usando datos de encuestas nacionales. Encontramos que las plantas, las aves, los mamíferos, y los peces tienen una opinión pública claramente más positiva que los reptiles, los anfibios, los invertebrados y los microorganismos. Sin embargo, las personas que respondieron la encuesta indicaron que es esencial conservar a todas las especies animales no humanas, y que la importancia ecológica y la rareza son los factores más importantes a considerar al priorizar las especies para su conservación. Medimos el poder político asociado a tipos de especies por medio del número de organizaciones no gubernamentales que los representan. Las aves tienen una importancia substancial en relación a todos los otros tipos. Usamos un modelo desarrollado para ciencias políticas que identifica los sujetos de la política en base a la opinión pública y el poder político, e identificamos a las aves, los mamíferos, y los peces como sujetos “con ventaja,” las plantas como sujetos “dependientes,” y los reptiles, los anfibios, los invertebrados y los microorganismos como sujetos “desviados de lo común.” Numerosas excepciones, especialmente entre mamíferos, son descritas como “contendientes.” Las discrepancias entre la valuación pública y la distribución de recursos para esfuerzos de recuperación son consistentes con las predicciones del modelo. Se concluye que hay un gran número de valores que convergen a favor de las aves, los mamíferos, los peces, y las plantas en el terreno político. Sin embargo, las oportunidades más prometedoras para la conservación de especies en el terreno político pueden estar en las plantas y los anfibios, para los que el cociente entre la opinión pública y la distribución de beneficios es la más alta.

The United States Fish and Wildlife Service's (USFWS) designation of critical habitat for the endangered Nelson's bighorn sheep (Ovis canadensis nelsoni) in the Peninsular Ranges of southern California has been controversial because of an absence of a quantitative, repeatable scientific approach to the designation of critical habitat. We used 12,411 locations of Nelson's bighorn sheep collected from 1984–1998 to evaluate habitat use within 398 km2 of the USFWS‐designated critical habitat in the northern Santa Rosa Mountains, Riverside County, California. We developed a multiple logistic regression model to evaluate and predict the probability of bighorn use versus non‐use of native landscapes. Habitat predictor variables included elevation, slope, ruggedness, slope aspect, proximity to water, and distance from minimum expanses of escape habitat. We used Earth Resources Data Analysis System Geographic Information System (ERDAS‐GIS) software to view, retrieve, and format predictor values for input to the Statistical Analysis Systems (SAS) software. To adequately account for habitat landscape diversity, we carried out an unsupervised classification at the outset of data inquiry using a maximum‐likelihood clustering scheme implemented in ERDAS. We used the strata resulting from the unsupervised classification in a stratified random sampling scheme to minimize data loads required for model development. Based on 5 predictor variables, the habitat model correctly classified >96% of observed bighorn sheep locations. Proximity to perennial water was the best predictor variable. Ninety‐seven percent of the observations were within 3 km of perennial water. Exercising the model over the northern Santa Rosa Mountain study area provided probabilities of bighorn use at a 30 times 30‐m2 pixel level. Within the 398 km2 of USFWS‐designated critical habitat, only 34% had a graded probability of bighorn use to non‐use ranging from ≥1:1 to 6,044:1. The remaining 66% of the study area had odds of having bighorn use <1:1 or it was more likely not to be used by bighorn sheep. The USFWS designation of critical habitat included areas (45 km2) of importance (2.5 to ≥40 observations per km2 per year) to Nelson's bighorn sheep and large landscapes (353 km2) that do not appear to be used (<1 observation per km2 per year).