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Brent Sigafus grew up in Tucson and began working with the USGS as an undergraduate at the University of Arizona in 2000, creating a specimen inventory database in collaboration with the USGS and National Park Service for the National Park Service Inventory and Monitoring Program. After graduating with a B.S. in natural resources, he became a volunteer for the USGS, focusing on data collection for bullfrogs and other desert amphibians, as well as assisting with mapping bullfrog dispersal. He began working with the USGS full-time in 2001 as a University of Arizona, Research Specialist for herpetologist Cecil Schwalbe. In 2009 Brent switched from a University employee to a USGS employee as a Biologist allowing him to expand into other scientific and support roles.
These days, Brent wears many hats. As a biologist, working on the Amphibian Research and Monitoring Initiative (https://armi.usgs.gov/), he supports amphibian projects across Arizona. Most of his time now is spent as the Collateral Duty Safety Program Director for the Southwest Biological Science Center leading all aspects of safety support from instructing classes like Wilderness First Aid and Animal Behavior to implementation of procedures and policies to keep our workforce safe. On a Bureau level he is the Southwest and Northwest-Pacific Islands Regional Firearms Safety Manager where he instructs others on the safe handling of firearms for Defense Against Wild Animals and Specimen Collection.
Science and Products
Modeling Colonization of a Population of Chiricahua Leopard Frogs
Amphibian Chytrid Fungus Sampling in Arizona and Mexico
Successful eradication of invasive American bullfrogs leads to coextirpation of emerging pathogens
Empirical evidence for effects of invasive American Bullfrogs on occurrence of native amphibians and emerging pathogens
Identifying factors linked with persistence of reintroduced populations: Lessons learned from 25 years of amphibian translocations
Distribution of tiger salamanders in northern Sonora, Mexico: Comparison of sampling methods and possible implications for an endangered subspecies
Staggered-entry analysis of breeding phenology and occupancy dynamics of Arizona toads from historically occupied habitats of New Mexico, USA
Accommodating the role of site memory in dynamic species distribution models
Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
Estimating inundation of small waterbodies with sub-pixel analysis of Landsat imagery: Long-term trends in surface water area and evaluation of common drought indices
Informing amphibian conservation efforts with abundance-based metapopulation models
Survival estimates for the invasive American bullfrog
Co-occurence of Chiricahua leopard frogs (Lithobates chiricahuensis) with sunfish (Lepomis)
Using full and partial unmixing algorithms to estimate the inundation extent of small, isolated stock ponds in an arid landscape
Science and Products
- Science
Modeling Colonization of a Population of Chiricahua Leopard Frogs
Managing a species with intensive tools like reintroduction may focus on single sites or entire landscapes. For mobile species like the federally-threatened Chiricahua leopard frog (Lithobates chiricahuensis [CLF]), both suitable colonization sites and suitable dispersal corridors between sites are needed. Following the eradication of the invasive American bullfrog (Lithobates catesbeianus) from...Amphibian Chytrid Fungus Sampling in Arizona and Mexico
Information on disease presence can be of use to natural resource managers, especially in areas supporting threatened and endangered species that occur coincidentally with species that are suspected vectors for disease. A general sense of pathogen presence (or absence) can inform management directed at threatened and endangered species, especially in regions where disease is suspected to have... - Publications
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Successful eradication of invasive American bullfrogs leads to coextirpation of emerging pathogens
Interventions of the host–pathogen dynamics provide strong tests of relationships, yet they are still rarely applied across multiple populations. After American bullfrogs (Rana catesbeiana) invaded a wildlife refuge where federally threatened Chiricahua leopard frogs (R. chiricahuensis) were reintroduced 12 years prior, managers launched a landscape-scale eradication effort to help ensure continueAuthorsBlake R. Hossack, David L. Hall, Catherine L. Crawford, Caren S. Goldberg, Erin L. Muths, Brent H. Sigafus, Thierry ChambertEmpirical evidence for effects of invasive American Bullfrogs on occurrence of native amphibians and emerging pathogens
Invasive species and emerging infectious diseases are two of the greatest threats to biodiversity. American Bullfrogs (Rana [Lithobates] catesbeiana), which have been introduced to many parts of the world, are often linked with declines of native amphibians via predation and spreading emerging pathogens such as amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]) and ranaviruses. AlthougAuthorsBlake R. Hossack, Emily B Oja, Audrey K Owens, David L. Hall, Cassidi Cobos, Catherine L. Crawford, Caren S. Goldberg, Shaula Hedwell, Paige E. Howell, Julio A. Lemos-Espinal, Susan K MacVean, Magnus McCaffery, Cody Mosley, Erin L. Muths, Brent H. Sigafus, Micahel J Sredl, James C. RorabaughIdentifying factors linked with persistence of reintroduced populations: Lessons learned from 25 years of amphibian translocations
Conservation translocations are increasingly used to help recover imperiled species. However, success of establishing populations remains low, especially for amphibians. Identifying factors associated with translocation success can help increase efficiency and efficacy of recovery efforts. Since the 1990s, several captive and semi-captive facilities have produced Chiricahua Leopard Frogs (Rana chiAuthorsBlake R. Hossack, Paige E. Howell, Audrey K Owens, C Cobos, Caren S. Goldberg, David L. Hall, Shaula Hedwall, Susi MacVean, Magnus McCaffery, A. Hunter McCall, C Mosley, Emily Bea Oja, James C. Rorabaugh, Brent H. Sigafus, Michael J SredlDistribution of tiger salamanders in northern Sonora, Mexico: Comparison of sampling methods and possible implications for an endangered subspecies
Many aquatic species in the arid USA-Mexico borderlands region are imperiled, but limited information on distributions and threats often hinders management. To provide information on the distribution of the Western Tiger Salamander (Ambystoma mavortium), including the USA-federally endangered Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi), we used traditional (seines, dip-nets) and moderAuthorsBlake R. Hossack, Julio A. Lemos-Espinal, Brent H. Sigafus, Erin L. Muths, Gerardo Carreon Arroyo, Daniel Toyos Martinez, David Hurtado Felix, Guillermo Molina Padilla, C. S. Goldberg, T. R. Jones, M. J. Sredl, Thierry Chambert, J. C. RorabaughStaggered-entry analysis of breeding phenology and occupancy dynamics of Arizona toads from historically occupied habitats of New Mexico, USA
For species with variable phenology, it is often challenging to produce reliable estimates of population dynamics or changes in occupancy. The Arizona Toad (Anaxyrus microscaphus) is a southwestern USA endemic that has been petitioned for legal protection, but status assessments are limited by a lack of information on population trends. Also, timing and consistency of Arizona Toad breeding variesAuthorsMJ Forzley, Mason J. Ryan, IM Latella, JT Giermakowski, Erin L. Muths, Brent H. Sigafus, Blake R. HossackAccommodating the role of site memory in dynamic species distribution models
First-order dynamic occupancy models (FODOMs) are a class of state-space model in which the true state (occurrence) is observed imperfectly. An important assumption of FODOMs is that site dynamics only depend on the current state and that variations in dynamic processes are adequately captured with covariates or random effects. However, it is often difficult to understand and/or measure the covariAuthorsGraziella Vittoria Direnzo, David A. W. Miller, Blake R. Hossack, Brent H. Sigafus, Paige E. Howell, Erin L. Muths, Evan H. Campbell GrantBatrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the lAuthorsHardin Waddle, Daniel A. Grear, Brittany Mosher, Evan H. Campbell Grant, Michael J. Adams, Adam R. Backlin, William Barichivich, Adrianne B. Brand, Gary M. Bucciarelli, Daniel L. Calhoun, Tara Chestnut, Jon M. Davenport, Andrew E. Dietrich, Robert N. Fisher, Brad Glorioso, Brian J. Halstead, Marc P Hayes, R. Ken Honeycutt, Blake R. Hossack, Patrick M. Kleeman, Julio A. Lemos-Espinal, Jeffrey M. Lorch, Robert W. Atkinson, Erin L. Muths, Christopher Pearl, Katherine Richgels, Charles W Robinson, Mark F. Roth, Jennifer Rowe, Walter Sadinski, Brent H. Sigafus, Iga Stasiak, Samuel Sweet, Susan C. Walls, Gregory J Watkins-Colwell, C. LeAnn White, Lori A Williams, Megan E. WinzelerEstimating inundation of small waterbodies with sub-pixel analysis of Landsat imagery: Long-term trends in surface water area and evaluation of common drought indices
Small waterbodies are numerically dominant in many landscapes and provide several important ecosystem services, but automated measurement of waterbodies smaller than a standard Landsat pixel (0.09 ha) remains challenging. To further evaluate sub‐Landsat pixel techniques for estimating inundation extent of small waterbodies (basin area: 0.06–1.79 ha), we used a partial spectral unmixing method withAuthorsIbrahima Sall, Christopher J. Jarchow, Brent H. Sigafus, Lisa A Eby, Michael James Forzley, Blake R. HossackInforming amphibian conservation efforts with abundance-based metapopulation models
Science-based management strategies are needed to halt or reverse the global decline of amphibians. In many cases, sound management requires reliable models built using monitoring data. Historically, monitoring and statistical modeling efforts have focused on estimating occupancy using detection–nondetection data. Spatial occupancy models are useful for studying colonization–extinction dynamics, bAuthorsPaige E Howell, Blake R. Hossack, Erin L. Muths, Brent H. Sigafus, Richard B. ChandlerSurvival estimates for the invasive American bullfrog
American bullfrogs (Lithobates catesbeianus) are significant invaders in many places and can negatively impact native species. Despite their impact and wide distribution, little is known about their demography. We used five years of capture mark-recapture data to estimate annual apparent survival of post-metamorphic bullfrogs in a population on the Buenos Aires National Wildlife Refuge in their inAuthorsPaige E. Howell, Erin L. Muths, Brent H. Sigafus, Blake R. HossackCo-occurence of Chiricahua leopard frogs (Lithobates chiricahuensis) with sunfish (Lepomis)
Invasive species are a major threat to the persistence of native species, particularly in systems where ephemeral aquatic habitats have been replaced by permanent water and predators, such as fish, have been introduced. Within the Altar Valley, Arizona, the invasive American bullfrog, Lithobates catesbeianus (formerly Rana catesbeianus), has been successfully eradicated to help recover ChiricahuaAuthorsPaige E. Howell, Brent H. Sigafus, Blake R. Hossack, Erin L. MuthsUsing full and partial unmixing algorithms to estimate the inundation extent of small, isolated stock ponds in an arid landscape
Many natural wetlands around the world have disappeared or been replaced, resulting in the dependence of many wildlife species on small, artificial earthen stock ponds. These ponds provide critical wildlife habitat, such that the accurate detection of water and assessment of inundation extent is required. We applied a full (linear spectral mixture analysis; LSMA) and partial (matched filtering; MFAuthorsChristopher Jarchow, Brent H. Sigafus, Erin L. Muths, Blake R. Hossack - News