Filters: Tags: USGS-EMA-LOW-PL Mojave Desert/SW Desert (X)
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During a multi-year demographic study of Agassiz’s desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area (Natural Area), in the western Mojave Desert, USA, we recorded evidence of evidence of mesocarnivores that commonly prey on desert tortoises on a 7.77 square-kilometer study area. The study area included land inside and outside the fenced boundary of the Natural Area. We recorded locations, condition and recency of sign, and type of sign present at burrows, dens, and den complexes used by desert kit foxes (Vulpes macrotis), coyotes (Canis latrans), American badgers (Taxidea taxus), and bobcats (Lynx rufus). We also recorded scat piles by species using them, amount, and relative ages...
Categories: Data;
Tags: California,
Desert Tortoise Research Natural Area,
Mojave Desert,
USGS-EMA-LOW-PL Mojave Desert/SW Desert,
biota,
During the five-survey years at the Desert Tortoise Research Natural Area in the western Mojave Desert of California, 1,645 sightings of 13 species of avian predators were collected. Eleven species occurred both inside and outside the fenced Desert Tortoise Research Natural Area, and two species, the short-eared owl and great horned owl, occurred only inside the fence. The most abundant predator was the common raven with more observations outside the fence than inside the fence in most years. Ravens are hyper-predators of the desert tortoise and, at the Desert Tortoise Research Natural Area, are one of four drivers of population decline. This species also inhibits recovery because of the high numbers (Berry et al....
Data on annual and perennial plants were collected during four survey years (1989, 1993, 1997, and 2012) at a 7.77 sq. km the Desert Tortoise Research Natural Area in the western Mojave Desert as part of a long-term research project on populations and habitat of the threatened desert tortoise (Gopherus agassizii) spanning 34 years. The data collection and analysis involved comparisons of vegetation inside and outside the fenced Desert Tortoise Research Natural Area.
Categories: Data;
Tags: California,
Desert Tortoise Research Natural Area,
Mojave Desert,
USGS-EMA-LOW-PL Mojave Desert/SW Desert,
biota,
The database on shell-skeletal remains from 1980 through 2012 was collected as part of a monograph covering the desert tortoise populations inside and outside the fenced Desert Tortoise Research Natural Area during a period of population decline. The principal objectives of the study were to compare trends in demographic and habitat data inside the protective fence with those outside the fence. Populations and habitat outside the fence were unprotected from recreational vehicle use and sheep grazing. Data for each shell-skeletal remain found on the long-term, 7.77 square kilometers plot, included carcass number, previous number as a live tortoise, date of collection, date last observed if marked; known or estimated...
A long-term research project was conducted on Agassiz’s desert tortoises (Gopherus agassizii) at a 7.77 square kilometer plot at the Desert Tortoise Research Natural Area, Western Mojave Desert, California, USA. The plot included tortoise populations and habitat both inside and outside the protective fence at the Research Natural Area. Databases used in the research and publications from the research project are assembled here and include: census (survey) database used for the demographic analysis and Bayesian modeling of the desert tortoise population; shell-skeletal remains of desert tortoises; clinical signs of health, disease, and trauma in desert tortoises; perennial (shrubs, perennial grasses) and annual plant...
This collection includes shell-skeletal remains of Gopherus agassizii from 1980 through 2012 that was collected as part of a monograph covering the desert tortoise populations inside and outside the fenced Desert Tortoise Research Natural Area of California during a period of population decline. The principal objectives of the study were to compare trends in demographic and habitat data inside the protective fence with those outside the fence. Populations and habitat outside the fence were unprotected from recreational vehicle use and sheep grazing. Data for each shell-skeletal remain found on the long-term, 7.77 square kilometers plot, included carcass number, previous number as a live tortoise, date of collection,...
Categories: Collection,
Data;
Tags: California,
Collection,
Desert Tortoise Research Natural Area,
Mojave Desert,
USGS-EMA-LOW-PL Mojave Desert/SW Desert,
We developed a model for analyzing multi-year demographic data for long-lived animals and used data from a population of Agassiz’s desert tortoise (Gopherus agassizii) at the Desert Tortoise Research Natural Area in the western Mojave Desert of California, USA, as a case study. The study area was 7.77 square kilometers and included two locations: inside and outside the fenced boundary. The wildlife-permeable, protective fence was designed to prevent entry from vehicle users and sheep grazing. We collected mark-recapture data from 1,123 tortoises during 7 annual surveys consisting of two censuses each over a 34-year period. We used a Bayesian modeling framework to develop a multistate Jolly-Seber model because of...
Clinical signs of health, disease, and trauma were collected as part of a long-term research program on Agassiz’s desert tortoises (Gopherus agassizii) at a 7.77 square km plot at the fenced Desert Tortoise Research Natural Area in the western Mojave Desert, USA. Surveys for health, infectious and non-infectious diseases were initiated in 1993, because of an outbreak of infectious upper respiratory tract disease caused by Mycoplasma agassizii, M. testudineum, and possibly herpesvirus (TeHV2). The disease outbreak was discovered in 1988-1989. Moderate to severe clinical signs of upper respiratory tract disease increased over time on four surveys, from 1993 through 2012. Moderate to severe signs of shell lesions (cutaneous...
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