Filters: Tags: Desert tortoise (X)
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This dataset provides spatial predictions of habitat suitability for Gopherus agassizii (Agassiz’s desert tortoise), Gopherus morafkai (Morafka’s desert tortoise) and a pooled-species model under current conditions (1950 – 2000 yr). The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to evaluate subtle ecological niche differences between G. agassizii and G. morafkai, and identify local species-environment relationships. Spatial predictions of habitat suitability were created using MaxEnt version 3.4.0 (Phillips et al., 2006), a widely-used software for SDM in presence-background frameworks. Detailed methods are provided in Inman et al. 2019. Inman et al. 2019. Local niche...
The relationships between Mycoplasma agassizii, a causative agent of upper respiratory disease (URTD), and desert tortoise (Gopherus agassizii), generally illustrate the complexities of disease dynamics in wild vertebrate populations. In this review, we summarize current understanding of URTD in Mojave desert tortoise populations, we illustrate how inadequate knowledge of tortoise immune systems may obfuscate assessment of disease, and we suggest approaches to future management of URTD in desert tortoise populations. We challenge the view that M. agassizii causes consistent levels of morbidity and/or mortality across the Mojave desert. Instead, URTD may be described more accurately as a context-dependent disease....
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Biological Conservation,
Conservation,
Desert tortoise,
Epidemiology,
Natural antibody,
This dataset provides spatial predictions of clustering and the genotype association index for the Mojave genotype in local species-environment relationships of Desert Tortoises (Gopherus agassizi and Gopherus morafkaii) for individuals in the subregion encompassing the genetic sampling locations used by Edwards et al. (2015). This region offered an opportunity to explore habitat selection across the ecotone between the Mojave and Sonoran deserts and the secondary contact zone between G. agassizii and G. morafkai, and is referred to as the focal study area. The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to identify multivariate clusters and map them back to geographic space....
This dataset provides spatial predictions of the pooled-SDM residuals from a multiscale geographically weighted regression model (MGWR) and the resulting local R2 values for individuals in the subregion encompassing the genetic sampling locations used by Edwards et al. (2015). This region offered an opportunity to explore habitat selection across the ecotone between the Mojave and Sonoran deserts and the secondary contact zone between G. agassizii and G. morafkai, and is referred to as the focal study area. The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to identify multivariate clusters and map them back to geographic space. Inman et al. 2019. Local niche differences predict...
This dataset depicts the distribution of Desert Tortoise habitat in Arizona. This dataset was obtained from Arizona GAP with no metadata.
In the Sonoran Desert of North America, populations of the desert tortoise (Gopherus agassizii) occur in rocky foothills throughout southwestern Arizona and northwestern Mexico. Although tortoise populations appear to be isolated from each other by low desert valleys, individuals occasionally move long distances between populations. Increasingly, these movements are hindered by habitat fragmentation due to anthropogenic landscape changes. We used molecular techniques and radiotelemetry to examine movement patterns of desert tortoises in southern Arizona. We collected blood samples from 170 individuals in nine mountain ranges and analyzed variability in seven microsatellite loci to determine genetic differentiation...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Conservation Genetics,
Gopherus agassizii,
conservation,
desert tortoise,
gene flow,
1. 1. Deep body and shell surface temperatures were monitored via radio-telemetry from unrestrained desert tortoises in their natural habitat. 2. 2. The surface of the carapace acts as a buffer against solar radiation, resulting in deep body temperatures up to 10�C below shell surface at the time of the midday retreat to burrows. 3. 3. The burrow of the desert tortoise provides the only ambient temperatures at ground level which are below the lethal range for this species during midday hours. 4. 4. Evening retreat to burrows permits an extension of higher body temperatures into the mid-evening hours. 5. 5. The use of evening burrow retreats lessens in mid-summer. This behavioral change results in lower body temperatures...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Comparative Biochemistry and Physiology,
Desert tortoise,
Gopherus agassizii,
burrow system,
radiotelemetry,
Egg production by desert tortoises was estimated at two sites in San Bernardino, California: Ivanpah Valley in 1980 and 1981 and Goffs in 1983, 1984 and 1985. Mean clutch frequencies were estimated for 1980 (1.60) and 1981 (1.10) from mass changes observed among sexually mature females weighed every 1-2 wk. Mean clutch frequencies in 1983 (1.89), 1984 (1.57) and 1985 (1.75) were estimated from periodic X-rays of females. Clutch sizes were also determined from radiographs. Tortoises at Goffs typically laid 1-2 clutches during May and June, but one female failed to lay eggs in 1984 and single tortoises laid three clutches in 1983 and 1985. If tortoises laid two clutches, the second was faintly visible in X-rays within...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Clutch frequency,
Clutch size,
Desert tortoise,
Egg production,
Hatching success,
This USFWS data set has been modified by NatureServe to include critical habitat only within the Central Basin and Range, and Mojave Basin and Range ecoregions, and further modified to include only the desert tortoise (Gopherus agassizii). These data identify, in general, the areas where final critical habitat exist for species listed as endangered or threatened.
Types: Downloadable;
Tags: BLM,
Bureau of Land Management,
CBR 2010,
Central Basin and Range,
Critical Habitat,
The purpose of this layer is to depict information relevant to the conservation of the desert tortoise (Gopherus agassizii) under the Desert Renewable Energy Conservation Plan (DRECP). Its extent includes all desert tortoise conservation areas (TCAs) identified in the US Fish and Wildlife Service's (USFWS) recovery plan for the desert tortoise and a series of least cost pathway linkages that connect these TCAs. The least cost pathway linkages were mapped by the USFWS Desert Tortoise Recovery Office (DTRO) and the University of Redlands. For the purpose of DRECP planning, this layer provides a more detailed assessment of this broad conservation network and identifies how different geographic areas within this network...
The USGS GAP Analysis Program has developed range maps and distribution models for 1401 species, 604 of which are found within the SRLCC. This record's parent folder contains several examples of GAP species web services. The GAP website has a complete list of available web services for species as well as a map viewer for species data. Species: Desert Tortoise (Gopherus agassizii) There are two web services for this species: the range map, showing the geographic limits within which the species can be found, and a distribution model, which predicts the environment within the range that is suitable for occupation by the species. Link to metadata for GAP range maps and distribution models. To access services, select...
Digitized vector data of Desert Tortoise (gopherus agassizii suitable habitat in Arizona. Digitized from 1:100,000 scale manuscripts prepared by Field Office Wildlife Specialists or digitized on-screen and edited at 1:100,000 scale or larger by GIS specialists. The criteria used included elevation, terrain, climate and vegetation. Category definitions: Category 1: 1. Habitat Area essential to maintenance of large, viable populations. 2. Conflicts are resolvable. 3. Medium to high density or low density contiguous with medium or high density. 4. Increasing, stable, or decreasing population.Category 2: 1. Habitat Area may be essential to maintenance of viable population. 2. Most conflicts are resolvable. 3. Medium...
This dataset depicts the distribution of Desert Tortoise habitat in Arizona. This dataset was obtained from Arizona GAP with no metadata.
This dataset represents current terrestrial intactness values (estimated at the 1km level) within the modeled distribution of the Desert tortoise (Gopherus agassizii). Terrestrial intactness is high in areas where development is low, vegetation intactness is high, and fragmentation is low. Consequently, this dataset serves as a general* indication of habitat quality within the distribution of this conservation element. Estimates of current terrestrial intactness were generated by an EEMS fuzzy logic model that integrates multiple measures of landscape development and vegetation intactness, including agriculture development (from LANDFIRE EVT v1.1), urban development (from LANDFIRE EVT v1.1 and NLCD Impervious Surfaces),...
This dataset provides the environmental explanatory variables used to explore spatial patterns in species-environment relationships in Gopherus agassizii and Gopherus morafkai across the subregion encompassing the genetic sampling locations used by Edwards et al. (2015). This region offered an opportunity to explore habitat selection across the ecotone between the Mojave and Sonoran deserts and the secondary contact zone between G. agassizii and G. morafkai, and is referred to as the focal study area. The raster layers contained here accompany the manuscript Inman et al. 2019 and were used to identify multivariate clusters and map them back to geographic space. Inman et al. 2019. Local niche differences predict...
The Moj_ConservationAreas layer is a mosaic of data including the Arizona, California, Nevada, and Utah Areas of Critical Environmental Concern (ACEC), Critical Habitat Unit (CHU), the Red Cliffs Desert Reserve (RCDR), the Desert Tortoise Conservation Center (DTCC), the Desert National Wildlife Refuge, State and National Parks, National Monuments, National Conservation Areas, Beaver Dam Wash National Conservation Area, and the Boulder City Conservation Easement (BCCE). Landownership classification for Wilderness Areas and Wilderness Study Areas, Department of Defense and Department of Energy were also included.
Types: Downloadable;
Tags: ACEC,
Areas of Critical Environmental Concern,
BLM,
Bureau of Land Management,
DOI,
Desert Tortoise Range and Habitats in the Northern Portion of extent.
This USFWS data set has been clipped by NatureServe to include critical habitat only within the Central Basin and Range, and Mojave Basin and Range ecoregions, and extracted to include only the desert tortoise (Gopherus agassizii) critical habitat areas. These data identify, in general, the areas where final critical habitat exist for species listed as endangered or threatened.
We constructed minimum convex polygon (MCP) home ranges for free-ranging desert tortoises from a natural population adjacent to the Desert Tortoise Conservation Center, near Las Vegas, NV. Home range area estimates were not significantly different from those estimated for other desert tortoises in the Mojave and Sonoran deserts. Male tortoises had significantly larger and more variable home ranges in a combined statistical analysis of this study with those of Burge (1977) and Barrett (1990). Bootstrap analysis of the MCP polygon areas suggested substantial autocorrelation of the tortoise sightings despite a mean interval between recaptures of 3.2 days, violating an assumption of nearly all home range estimation...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Desert tortoise,
Herpetological Monographs,
Home range,
Minimum convex polygon,
Testudinidae
The Desert Tortoise (Gopherus agassizii) species distribution model includes a continuous probability surface from the USGS statistical model completed by Kenneth E. Nussear, Todd C. Esque, Richard D. Inman, Leila Gass, Kathryn A. Thomas, Cynthia S. A. Wallace, Joan B. Blainey, David M. Miller, and Robert H. Webb and a binary layer produced by the Conservation Biology Institute. The binary layer depicts predicted suitable habitat using the equal training sensitivity and specificity threshold (0.506). The binary output was also processed to exclude agriculture, developed, and disturbed areas, based on the DRECP land cover/natural vegetation dataset provided by Todd Keeler-Wolf of the CA Dept. of Fish and Game. The...
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