Jorge H. Valdez-Villavicencio

• MS - Maestro en Ciencias
• Research Coordinator at Conservacion de Fauna del Noroeste, A.C.

We document observations on the reproduction of Emys pallida in drainages from the western Sierra San Pedro Mártir, Baja California, México. These are the first reported observations from Baja California populations of this species mating in the wild.!

The California Red-legged Frog (Rana draytonii) is a threatened species in the United States that has undergone population declines, especially in southern California. Due to the lack of information on the status of Mexican populations, we surveyed for the presence of R. draytonii in Baja California and assessed possible threats to population persi...

Se registra una nueva población de la tortuga de poza del suroeste Emys pallida en Baja California. Este registro representa una ampliación en la distribución de 95.5km al sur del registro previo más sureño. También representa la única población de oasis dentro de la ecorregión del Desierto Central en Baja California.

A new population of Ensatina eschscholtzii klauberi in the San Quintín volcanic field, Baja California, represents the first coastal population of this taxon. This record extends the range ca. 71 km southwest of the southernmost record of E. e. klauberi in the Sierra San Pedro Mártir and represents the first population discovered outside of conifer...

We studied a remote and robust population of Actinemys pallida (Southwestern Pond Turtle) in the upper Río Santo Domingo (RSD) watershed, Sierra San Pedro Mártir, Baja California, Mexico. We conducted cursory assessments in 2014 and 2015 and intensive trap-based surveys in 2016 and 2022. We captured and marked 486 unique turtles a total of 597 time...

Resumen.-Para proteger especies amenazadas como la rana de patas rojas de California (Rana draytonii), es importante conocer su historia natural, incluyendo las relaciones de la red alimenticia. Reportamos las primeras observaciones de R. draytonii comiendo e intentando comer avispas caza tarántulas (Pepsis sp.) en los matorrales montanos xerofític...

Invasive alien species pose a significant threat to global biodiversity. In the Baja California Peninsula (Mexico), these organisms have proliferated, and measures taken have been insufficient to mitigate their expansion and reduce their environmental impact. In this study, a specific eradication index was developed for the American bullfrog (Litho...

Analizamos la composición alimentaria de la rana toro exótica (Aquarana catesbeiana) en un humedal de montaña de Baja California cerca de la frontera México-Estados Unidos, durante la primavera y verano de 2016. Examinamos el contenido estomacal de 65 especímenes por sexo, edad y talla. Además, cuantificamos la contribución integral de las presas (...

Resumen.-La cifosis es una condición física definida como una deformidad dorsalmente convexa de la columna en el plano sagital del animal, y en el caso de tortugas, se observa una curvatura o joroba en el caparazón. Durante los estudios de monitoreo de la tortuga de poza Actinemys pallida en el Arroyo San Rafael, Baja California, encontramos dos in...

Exotic species introductions are a major threat to biodiversity. The first step to their control involves identifying their presence, distribution, and impacts on native species and their habitats, especially in highly diverse regions. We update and document new records of exotic freshwater fauna from the Baja California Mediterranean region. We fo...

The Mexican Conservation Series (MCS) was initiated in 2013, with a study of the herpetofauna of Michoacán (Alvarado-Díaz et al. 2013) that was published as part of a set of fve papers designated as the Special Mexico Issue in Amphibian & Reptile Conservation. The basic format of the entries in the MCS was established in that paper, i.e., examining...

Understanding how historical geological processes drive diversification and shape the contemporary distribution of species is fundamental to phylogeography. We take a genomic approach in order to elucidate the deep phylogeographical history and species limits of chuckwallas (Sauromalus), a conspicuous group of lizards of the arid lands of south-wes...

We document mobbing toward the Mexican West Coast Boa Constrictor (Boa sigma) by different species of birds in Sonora, Mexico.

En el marco del XVI Congreso Nacional de Herpetología, se organizó el simposio "Estudios sobre tortugas dulceacuícolas y terrestres de México" donde se presentaron siete trabajos, con el mismo numero de especies. Estas presentaciones abordaron diversos aspectos de la biología y conservación de este grupo. Los resultados de estas investigaciones son...

Here we describe and confirm the westernmost record of the Short-nosed Rock Lizard (Petrosaurus repens) and provide comments about its distribution.

Account 930 of the Catalogue of American Amphibians and Reptiles

Here we present the first record of leucism in R. draytonii in Baja California.

Conservation translocations, the human-mediated movement and release of a living organism for a conservation benefit, are increasingly recommended in species’ recovery plans as a technique for mitigating population declines or augmenting genetic diversity. However, translocation protocols for species with broad distributions may require regionally...

We conducted an inventory of amphibians and reptiles within Rancho Las Playitas in northern Sonora, Mexico. The herpetofaunal diversity documented so far includes 5 amphibian species, all anurans, and 33 reptile species with 1 turtle, 13 lizards, and 19 snakes. We compare that with the known herpetofauna of several areas in the vicinity.

Viviparity, an innovation enhancing maternal control over developing embryos, has evolved >150 times in vertebrates, and has been proposed as an adaptation to inhabit cold habitats. Yet, the behavioral, physiological, morphological, and life history features associated with live-bearing remain unclear. Here, we capitalize on repeated origins of viv...

Restoration efforts have begun on a global scale, with the goal of reversing the impacts caused by exotic vegetation invading disturbed sites. The purpose of this study was to determine the response of amphibians and reptiles to habitat restoration in the Colorado River Delta, by comparing the richness and diversity of the herpetofauna in 2 restore...

Desert squamates need to regulate their body temperature within a specific range in response to extreme temperatures. Variation of thermal resources through altitudinal and latitudinal gradients influences the thermal physiological traits and thermoregulation of organisms. In some species, the physiological requirements between populations can vary...

Amphibians are declining globally, and the fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis, has been the culprit in many of these declines. In the Mediterranean region of Baja California, Mexico—a biodiversity hotspot—native amphibians are also in decline, and Bd is present. To determine which factors...

The Estero Punta Banda in Bahia Todos Santos, Baja California, is a coastal wetland of international importance considered a RAMSAR site and a priority area for biodiversity conservation. However, no formal studies have been carried out on the richness and diversity of amphibians and reptiles at this site, focused on knowing their richness and dive...

We report the first records of the Mediterranean House Gecko (Hemidactylus turcicus) in the state of Baja California Sur, Mexico

Distribution, ecology, and habitat use of the northernmost Boa sigma records (all from northeastern Sonora, Mexico).

Global climate change and the associated erosion of habitat suitability are pervasive threats to biodiversity. It is critical to identify specific stressors to assess a species vulnerability to extinction, especially in species with distinctive natural histories. Here, we present a combination of field, laboratory, and modeling approaches to evalua...

Viviparity is an evolutionary innovation that enhances maternal protection of developing embryos relative to egg-laying ancestors. The behavioral, physiological, morphological, and life history pathways underpinning this innovation, however, remain unclear. We capitalized on the repeated origin of viviparity in phrynosomatid lizards to tease apart...

We report the interspecific amplexus between the California Red-legged Frog (Rana draytonii) and the Western Toad (Anaxyrus boreas) in Baja California, Mexico.

Twenty-eight historical collection sites for Microtus californicus (California vole, CAVO) in Baja California, Mexico, are georeferenced; historical collections and descriptions are summarized; and, when possible, sites were visited to evaluate habitat and possible continued presence of CAVO. When the habitat indicated that detection of CAVO seemed...

We revisited 26 of the 28 known collection sites for the California vole, Microtus californicus, in Baja California, Mexico. With live trapping, we were able to confirm the continued presence of the vole at 7 of these sites, which include all 3 of the subspecies endemic to Baja California. At 14 of these sites, no viable habitat was found. These 14...

Sceloporus licki, an endemic lizard of the Cape Region from Baja California Sur, Mexico, shows evident sexual dimorphism in coloration and in snout‐vent length between males and females. The gonadal analysis showed that both sexes have a synchronous spring–summer reproductive cycle. The males show maximum gonadal activity from March to July; in Aug...

Resumen.-La necrofilia es un comportamiento reproductivo en el que un animal vivo intenta copular con un animal muerto. Este comportamiento se ha reportado en varias especies de lagartijas. Aquí presentamos el primer caso de necrofilia en Sceloporus zosteromus, observado en un macho adulto con una hembra de su misma especie en el noroeste de Baja C...

Western Ground Snake (Sonora mosaueri) geographic distribution in Baja California, Mexico.

Incidental entanglement of a specimen of Masticophis fuliginosus by discarded fishing material is reported in a Ramsar marsh area in the Estero Punta Banda in Baja California, Mexico. This event is associated with the inadequate disposal of fishing gear waste within coastal areas. This unusual record represents the first case of entanglement or pos...

Se reporta la afectación incidental de un espécimen de Masticophis fuliginosus por restos de material de pesca, en una zona de marismas del sitio Ramsar Estero de Punta Banda, Ensenada, Baja California, México. Este evento se asocia a la disposición inadecuada de residuos derivados de la labor pesquera dentro de las áreas costeras. Este registro in...

We revisited 26 of the 28 known collection sites for California vole, Microtus californicus, in Baja California, Mexico. With live trapping, we were able to confirm the continued presence of the vole at seven of these sites, which include all three of the subspecies endemic to Baja California. At 14 of these sites, no viable habitat was found. Thes...

We report the finding of two dead specimens of Uta stansburiana in a wind farm located in the town of La Rumorosa, Baja California. The mortality was associated with run-over on access roads and drowning in the sewer systems. The specimens were found in the period from August 2015 to August 2016 during the carcass search activities of the wildlife...

Global climate change is a major known threat against biodiversity, however, it is still unclear how it will affect different taxonomic groups as the answer is dependent on species-specific natural history and habitat complexity. Desert reptiles are of particular concern because they must thermoregulate within optimal limits despite high environmen...

New municipality record of H. turcicus in Baja California, Mexico

La lagartija sin patas de Baja California Anniella geronimensis es una lagartija de hábitos fosoriales microendémica de Baja California. Su núcleo de distribución se encuentra en las dunas costeras de la Bahía de San Quintín, la cual está siendo fuertemente invadida por el “hielito” (Carpobrotus sp), una especie de planta suculenta proveniente del...

El Estero de Punta Banda se encuentra al sur de la ciudad de Ensenada, Baja California, y es considerado humedal de importancia internacional por la Convención de Ramsar desde el 2006. Dicho sitio cuenta con variedad de hábitats como dunas costeras, playa arenosa, marismas, canales de marea, entre otros, lo cual permite la existencia de diversidad...

El hongo patógeno quítrido Batrachochytrium dendrobatidis (Bd), es de los principales factores responsables de la disminución de especies de anfibios a escala mundial. Los impactos del hongo se ven fluctuados por variables tanto bióticas como abióticas. Diversos estudios han encontrado que la temperatura tiene un papel importante en la ecología de...

Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and is regarded as one of the most significant threats to global amphibian populations. In México, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exot...

The US and Mexico share a common history in many areas, including language and culture. They face ecological changes due to the increased frequency and severity of droughts and rising energy demands; trends that entail economic costs for both nations and major implications for human well being. We describe an ongoing effort by the Environment Worki...

Recent climate change should result in expansion of species to northern or high elevation range margins,

Recent climate change should result in expansion of species to northern or high elevation range margins, and contraction at southern and low elevation margins in the northern hemisphere, because of local extirpations or range shifts or both. We combined museum occurrence records from both the continental U.S. and Mexico with a new eco-physiological...

Recent climate change should result in expansion of species to northern or high elevation range margins, and contraction at southern and low elevation margins due to extinction. Climate models predict dramatic extinctions and distributional shifts in the next century, but there are few ground-truths of these dire forecasts leading to uncertainty in...

First Municipality record of the exotic Gecko Hemidactylus turcicus in Baja California, Mexico.

Here we report an observation of E. multicarinata feeding upon a novel prey species.

Las colecciones científicas son de gran valor ya que representan el inventario de las especies presentes en cierta región y contienen información que es base de muchas líneas de investigación. Además, sirven como apoyo docente, y para dar a conocer a la sociedad la importancia de la biota de cierto lugar por medio de difusión y divulgación. La base...

Esta obra trata sobre los tesoros de las islas del Pacífico de Baja California, sus plantas y animales endémicos, aquellos que no se encuentran en ninguna otra parte del mundo. This book is a guide to the real treasures of the Baja California Pacific Islands, their endemic plants and animals, found here and nowhere else on the earth. PRÓLOGO POR /...

We provide a record and field observations of California vole (Microtus californicus) based on a specimen collected on 5 June 2013 in riparian habitat from Arroyo San Rafael, northwestern Sierra San Pedro Mártir, Baja California, México. The last known record of this species in México was in 1974. This species was suspected to be extirpated from Mé...

Sceloporus licki is a lizard endemic to the Cape Region in the southern extreme of Baja California Sur. It is generally restricted to Sierra La Laguna, were it inhabits pine-oak forest and oak-pine on the mountains tops as well as deciduous forest that surrounds this ecosystem. We report new distributional records extending their distribution to th...

The Baja California Coachwhip, Masticophis fuliginosus, has been reported to feed on small mammals, birds, small snakes, and lizards (Grismer, 2002). Grismer (2002) identified three species of lizards as prey items: Sceloporus grandaevus, Dipsosaurus dorsalis, and Aspidoscelis hyperythra. Additional prey species include Sonora semiannulata (Cliff,...

We report the first State record of the Brahminy Blind Snake (Indotyphlops braminus) in Baja California, Mexico.

First record of Hemidactylus frenatus (Common House Gecko), in Baja California, Mexico.

Northern distribution of Lithobathes forreri in Sonora, Mexico

The Baja California peninsula is inhabited by 116 native amphibians and reptiles. The Cape Region, located at the southern end of the peninsula, is one of the main areas of endemism, especially for reptiles. Comprehensive knowledge is lacking for any one specific region of the peninsula, including the Sierra Las Cacachilas, located in the northern...

We assessed the distribution and threats to Rana draytonii populations in Baja California, Mexico. Previous records dated from 1889 to 2006, with the Sierra San Pedro Mártir accounting for 90% of the records. We conducted surveys at 40 sites during 2013-2014. We observed R. draytonii at ten locations in three watersheds (San Rafael, San Telmo and S...

Body and preferred body temperatures of the San Lucan Alligator Lizard (Elgaria paucicarinata) from Sierra La Laguna, Baja California Sur, Mexico.

We provide information on recent records of the 2 subspecies of striped skunk occurring in the north- eastern (Mephitis mephitis estor) and northwestern (M. m. holzneri) region of Baja California, Mexico. Most of the recent records for these subspecies come from valleys and suburban zones. Aportamos registros recientes para las dos subespecies del...

The African clawed frog (Xenopus laevis) is an invasive amphibian in at least 15 countries. In Mexico, only occasional records have documented it in the state of Baja California. In May 2013, we discovered a population at Puente el Morro in Rosarito. In a 1-h session of trapping, we captured 106 individuals (adults and juveniles) at a small pond. W...

We studied the diet of the exotic American bullfrog (Lithobates catesbeianus) in Arroyo San Carlos, located in northwestern Baja California, Mexico, during spring and summer 2009. Analysis of 64 stomach contents revealed 15 prey types, of which the exotic red crayfish (Procambarus clarkii) and terrestrial isopods (Armadillidiidae) were the most sig...

First record of leucism in the Arboreal Salamander (Aneides lugubris) from Baja California, Mexico

Record of Ornate Tree Lizard (Urosaurus ornatus) on Isla Pajaros, Sonora, Mexico

We report on limb regeneration an the San Lucan Rock Lizard (Petrosaurus thalassinus) in the Cape Regio, Baja California Sur, Mexico.

Los límites ecológicos han sido de interés para los naturalistas desde los tiempos de Darwin y Wallace debido a que son zonas de transición en el paisaje donde ocurren cambios en la estructura de comunidades de plantas y animales. Los oasis de palma de abanico (Erythea armata y Washingtonia robusta) presentes en los ambientes xéricos de la región c...