Daniel J. Leavitt

Daniel J. Leavitt
U.S. Fish and Wildlife Service · Division of Ecological Services

Texas A&M University, PhD

About

71
Publications
19,444
Reads
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236
Citations
Introduction
Conservation biology, population demographic modeling, and management techniques for species at risk.
Additional affiliations
January 2013 - January 2018
Arizona Game and Fish Department
Position
  • Regional Wildlife Specialist Supervisor
August 2012 - December 2012
Georgia Southern University
Position
  • Research Assistant

Publications

Publications (71)
Article
Full-text available
Citation: Leavitt, D. J., and L. A. Fitzgerald. 2013. Disassembly of a dune-dwelling lizard community due to landscape fragmentation. Ecosphere 4(8): Abstract. Landscape fragmentation alters patterns of landscape structure that affect quality and configuration of habitats, and disrupts population dynamics and persistence of species. Community disas...
Article
Full-text available
Sonoran Desert habitat in southern Arizona is increasingly altered by urban development near metropolitan areas. Understanding how reptiles respond in these impacted habitats is critical to conservation efforts to retain intact biotic communities, especially those with a high diversity of reptile species. We surveyed snakes at one impacted site on...
Article
Full-text available
Monitoring programs for species of conservation concern are notoriously flawed. Notably, many monitoring programs do not establish trigger points or a level of decline in population size that will result in management action. Here we report on the monitoring program for the Flat-tailed Horned Lizard (Phrynosoma mcallii) that has been established ac...
Article
Full-text available
Hyla cinerea recently introduced to a Chihuahuan Desert wetland in Big Bend National Park, Texas consumed a variety of terrestrial arthropods. We investigated its diet to analyze a component of colonizing potential for this species. Of 105 individuals analyzed, we found a total of 194 prey items representing 13 unique categories. The most important...
Article
Ecology has long sought whether there are general assembly rules that underlie patterns of community organization. However, new perspectives of community disassembly and reassembly have emerged as environments depart from baseline conditions due to agents of global change. A trait-based approach can provide insights as to how changes affect perform...
Chapter
The Dunes Sagebrush Lizard (Sceloporus arenicolus) is endemic to the Mescalero-Monahans Sandhills, in southeastern New Mexico and west Texas. It only lives in dunes with bowl-shaped depressions (blowouts) that are semi-stabilized by shinnery oak (Quercus havardii). Meticulous studies reveal population dynamics in these lizards scale from local neig...
Technical Report
Full-text available
This report evaluates the population viability of Dunes Sagebrush Lizard in New Mexico, USA. Funding for this project was provided by the Center of Excellence for Hazardous Materials Management (CEHMM), the Candidate Conservation Agreement (CCA), and Candidate Conservation Agreement with Assurances (CCAA).
Article
Full-text available
Species conservation requires a clear understanding of habitat availability and subsequent use of those habitats. In cases where species declines have occurred and gone undetected by conservation managers , habitat alteration, fragmentation, and loss are often the largest contributors. River fragmentation often results in altered flow regimes, subs...
Chapter
Definitive species account, including etymology, and primary research by Arizona investigators on taxonomy; distribution and abundance; habitat use and ecology; reproductive, social, and hunting behaviors; prey use, parasites, and predators; and conservation status.
Article
Full-text available
Phylogeographic divergence and population genetic diversity within species reflect the impacts of habitat connectivity, demographics, and landscape level processes in both the recent and distant past. Characterizing patterns of differentiation across the geographic range of a species provides insight on the roles of organismal and environmental tra...
Preprint
Full-text available
Phylogeographic divergence and population genetic diversity within species reflect the impacts of habitat connectivity, demographics, and landscape level processes in both the recent and distant past. Characterizing patterns of differentiation across the geographic range of a species provides insight on the roles of organismal and environmental tra...
Article
Full-text available
The Sonoran Desert tortoise Gopherus morafkai is adapted to the desert, and plays an important ecological role in this environment. There is limited information on the viral diversity associated with tortoises (family Testudinidae), and to date no DNA virus has been identified associated with these animals. This study aimed to assess the diversity...
Technical Report
Full-text available
Range-wide PVA on Flat-tailed Horned Lizard populations
Article
Full-text available
Anthropogenic disturbances can have negative effects on species assemblages. This study was established to form baseline data on the environmental structure and reptile assemblages within a planned energy corridor in Pinal County, Arizona, prior to construction. We emphasized evaluating the differences in reptile assemblages in two subdivisions of...
Article
Full-text available
More than 80% of animals have complex life cycles and undergo distinct changes in ecology and morphology during development. The strength and type of factors regulating each life-stage may differ as an organism may occupy different niches during ontogeny. We examined the functional distance at larval and adult life-stages of two non-native anurans...
Technical Report
The Barry M. Goldwater Range-West (BMGR-W) includes 283,280 ha of Sonoran Desert near Yuma, Arizona. The Integrated Natural Resources Management Plan (INRMP) for the BMGR-W requires that baseline conditions for small mammals, reptiles, and amphibians be established so that natural resource managers may determine how best to allocate effort to prote...
Technical Report
Full-text available
Range-wide analysis for long-term monitoring of the Flat-tailed Horned Lizard.
Technical Report
Camp Navajo is an Arizona Army National Guard installation near Flagstaff, Arizona that has not had a comprehensive study of the amphibians and reptiles within its boundaries. We conducted planning-level surveys for amphibians and reptiles using visual encounter surveys, cover boards, drift fence trapping arrays, and remote audio recording devices...
Technical Report
Full-text available
The purpose of this study was to identify monitoring strategies for two species of amphibians on the lower Colorado River by evaluating the cost efficiency of different methods. Five different survey methods were evaluated for their ability to efficiently detect two study species, the Colorado River toad (Bufo alvarius = Incilius alvarius) and the...
Article
Full-text available
Surveys dedicated to better describing the distribution of Uma scoparia in Arizona are reported. These extend this species' distribution in La Paz County, Arizona, 20 km further to the south than previously described. Six records on the outside of a confused range are presented alongside data from 170 captures within this range. This species is wel...
Article
Full-text available
Landscape fragmentation alters biotic and abiotic characteristics of landscapes, variously affecting the size and demographic structure of species' populations. Fragmentation is predicted to negatively impact habitat specialists because of perturbations to their habitat, whereas generalists should be less sensitive to fragmentation. Differences in...
Technical Report
The Barry M. Goldwater Range-West (BMGR-W) includes 283,280 ha of Sonoran Desert near Yuma, Arizona. The Integrated Natural Resources Management Plan (INRMP) for the BMGRW requires that baseline conditions for small mammals, reptiles, and amphibians be established so that natural resource managers may determine how best to allocate effort to protec...
Technical Report
Full-text available
The purpose of this project was to survey for threatened and endangered species along the Santa Maria and Big Sandy rivers upstream of Alamo Lake. Surveys were conducted for Yellow-billed Cuckoos (Coccyzus americanus) and Mexican Garter Snakes (Thamnophis eques). Any additional information gathered on the occupancy of these species within this regi...
Article
Translocation to areas free of exotic predators, habitat degradation, or disease may be the most viable restoration option for many endangered species. We report on a successful translocation of the critically endangered St. Croix ground lizard, Ameiva polops, extirpated from St. Croix, U.S. Virgin Islands, Caribbean, by predation from introduced m...
Article
Full-text available
Monitoring programs for species of conservation concern are notoriously flawed. Notably, many monitoring programs do not establish trigger points or a level of decline in population size that will result in management action. Here we report on the monitoring program for the Flat-tailed Horned Lizard (Phrynosoma mcallii) that has been established ac...
Article
Full-text available
SD, range = 23-32 mm) collected in: Johor LSUHC 8211; Kedah LSUHC 10600; Pahang LSUHC 4417, 5148, 5175, 6126, 7254; Penang LSUHC 9991, 9992. A cut was made in the lower abdominal cavity and the left testis or ovary was removed, embedded in paraffin, cut into 5-µm sections and stained with Harris hematoxylin followed by eosin counterstain. Enlarged...
Technical Report
Full-text available
We conducted occupancy surveys for Sonoran desert tortoises (SDTs; Gopherus morafkai) at the Hummingbird Springs/Big Horn Wilderness Area (HS/BHWA), Maricopa County, Arizona from mid- July through early October, 2013. The survey objectives were to 1) permanently mark as many SDTs as possible found within the study area; 2) estimate occupancy and de...
Technical Report
Full-text available
This project evaluated the tortoise mitigation fence installed along segments of the north and south bound lanes of Arizona State Route 87 between mile posts 204 and 206. We compared results from road-mortality surveys along the newly installed mitigation fence and an adjacent control area between mile posts 206 and 208. We found one Sonoran desert...
Technical Report
Full-text available
We conducted occupancy surveys for Sonoran desert tortoise (SDT; Gopherus morafkai) at the Casa Grande Army National Guard Training Area (CGANGTA), Pinal County, Arizona. Our surveys were conducted between mid- July and mid- October, 2013 on 60 randomly selected 3 hectare (ha) plots and each plot was surveyed five times. We detected a total of 22 i...
Article
Full-text available
The Puerto Rican ground lizard (Ameiva exsul) was first documented on St. Croix, U.S. Virgin Islands in 2006. The species is native to Puerto Rico, the northern U.S. Virgin Islands, and the British Virgin Islands, and was purportedly transported to St. Croix with a shipment of goods. Ameiva exsul has since become established in a north- central nei...
Article
Full-text available
An observation of a previously unknown feeding behavior in Glossy Snakes
Article
Full-text available
Comparisons of assemblages of rodents along the Rio Grande in Big Bend National Park, Brewster County, Texas, were made using recent (2009–2010) and historic (1977) data to evaluate the effects of invasion by saltcedars (Tamarix). Comparisons of abundances and species of rodents between sites with mesquites (Prosopis), cottonwoods (Populus), or sal...
Article
Full-text available
The marbled whiptail (Aspidoscelis marmorata) is a common lizard within the Chihuahuan Desert of the United States—Mexico borderlands. We report a patternless female from the Mescalero—Monahans Shinnery Sands Ecosystem in southeastern New Mexico. One previous record of this pattern has been noted in the literature and this unique morphology has not...
Technical Report
Full-text available
Comprehensive strategies aimed at conservation of species and their habitats require integration of biophysical information on species and their habitats at multiple scales. Species conservation plans require information on habitat requirements, area and extent of habitat, geographic range, patterns of occupancy within suitable habitat, habitat spe...
Conference Paper
Background/Question/Methods Landscape fragmentation is generally accepted as a mechanism that disrupts structure of populations, species’ distributions and ecological communities. However, few studies have evaluated the extent to which metacommunity structure is affected following landscape fragmentation. Here we discuss an applied-field-ecologica...
Article
Full-text available
Esta investigación compara inventarios de vegetación que fueron realizados en el parque nacional Big Bend, condado de Brewster, Texas, durante 1955–1960 y 1968–1969 con información colectada en 2005 y 2006. Las comparaciones se basaron en porcentajes de cobertura y flora en cinco sitios. Los resultados sugieren algunos incrementos y decrementos de...
Article
Full-text available
Diet of the barn owl (Tyto alba) has been well studied in temperate regions of the world, but there is a notable paucity of dietary data from the Neotropics. In this study, we examined diet of barn owls at Gold Button Lagoon in northern Belize. Pellets and prey remains were collected at roosting sites during 1997–1998. Diet was composed primarily o...

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