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Habitat fragmentation threatens biodiversity worldwide, particularly affecting large-bodied species that require vast territories and move across long distances, including most large felids. The jaguar Panthera onca has lost more than half of its habitat throughout its range and its subpopulations are becoming isolated, making them susceptible to local extinction. Knowledge about the status of its subpopulations in highly fragmented environments is lacking but urgently needed. Using camera traps during 2019–2020, we estimated number of individuals, age classes and sex ratio, occupancy, relative abundance and density of jaguars in Nayarit, western Mexico. We also determined the relative abundance of potential prey and estimated the land-cover change rate during 1999–2019, using GIS. We found that a resident subpopulation of five adult females, two adult males and one cub, at a high density (5.3 individuals/100 km2), is supported by at least 14 wild prey species. Natural habitat in the area is rapidly decreasing because of expanding agriculture and shrimp farming: agricultural areas increased from 39 to 50% and mangroves decreased from 35 to 26% of the study area over 20 years. The high jaguar population density and the diversity and relative abundance of remaining wild prey are remarkable, considering that natural habitat in the area is highly fragmented, shrinking rapidly and embedded in a matrix of human-dominated land-cover types. Effective conservation actions are needed urgently, including the protection of patches with native vegetation, reforestation to maintain connectivity between these patches, and the involvement of local communities.

El gato montés, Lynx rufus, es una de las seis especies de felinos silvestres que habitan en México. Se distribuye desde el nivel del mar hasta los 3,600 m, ocupando una gran variedad de hábitats entre los que se encuentran los desiertos, ecosistemas de montaña y humedales. Sin embargo, a la fecha, no existe información ecológica de la especie en humedales costeros. El objetivo general de este trabajo es proveer la primera información ecológica obtenida de forma sistemática sobre el gato montés en la Planicie Costera de Nayarit (PCN). Evaluamos su presencia histórica y actual, su abundancia relativa y patrones de actividad. Determinamos la presencia histórica del gato montés en la PCN mediante una búsqueda en bases de datos electrónicas utilizando las palabras: “Lynx”, “rufus”, “lince”, “bobcat” y “Nayarit”. Implementamos el protocolo del Censo Nacional del Jaguar usando cámaras trampa en un área de 72 km2 para documentar la presencia, distribución, abundancia relativa y patrones de actividad del gato montés. A través de la búsqueda en bases de datos encontramos 23 registros de gato montés en un área de al menos 3,000 km2 de la PCN. A partir de nuestro trabajo de campo obtuvimos 30 registros independientes con una abundancia relativa de 1.28 fotografías de gato montés / 100 días cámara. Documentamos la presencia de al menos 10 individuos diferentes, incluyendo adultos de ambos sexos y una hembra presuntamente embarazada. Su actividad es nocturna; 40 % de los registros ocurrieron entre las 00:00-06:00 hr. El gato montés habita los ecosistemas costeros de Nayarit. Los valores elevados de abundancia relativa sugieren una población estable en la PCN con respecto a lo que ha sido reportada en hábitat ideales para la especie tales como los matorrales y bosques templados. Su actividad nocturna coincide con lo que reportan otros trabajos para la especie. Aunque, en general, el gato montés se adapta bien al disturbio generado por actividades humanas, los impactos que estas tienen sobre sus poblaciones en los humedales costeros aún se desconocen. Para asegurar la permanencia de sus poblaciones es necesario realizar futuros estudios sobre su dieta, reproducción, ámbito hogareño y conectividad genética de la especie en los ecosistemas costeros del occidente de México.

En el presente trabajo se analizo la alianza de los grupos de interes gobierno, sociedad y academia, desde la perspectiva de la gestion de los residuos solidos en la ciudad de Tepic, Nayarit, Mexico, con miras a la sostenibilidad. Para la evaluacion cuantitativa se utilizo el grado de alcance de la alianza expresada en la relacion de los grupos de interes conformada por los diferentes actores sociales, con base en una version adaptada de la metodologia de Cohen y Franco. Los resultados indican que a traves de la participacion de los grupos de interes en las actividades disenadas, se logro un avance del 31 % en la gestion de residuos solidos urbanos. Este trabajo demuestra que se puede establecer una gestion integral de los residuos solidos urbanos con la participacion correspondiente de los diferentes actores que conforman los grupos de interes.

The jaguar (Panthera onca) is one of the most threatened carnivores in the Americas. Despite a long history of research on this charismatic species, to date there have been few systematic efforts to assess its population size and status in most countries across its distribution range. We present here the results of the two National Jaguar Surveys for Mexico, the first national censuses in any country within the species distribution. We estimated jaguar densities from field data collected at 13 localities in 2008–2010 (2010 hereafter) and 11 localities in 2016–2018 (2018 hereafter). We used the 2010 census results as the basis to develop a National Jaguar Conservation Strategy that identified critical issues for jaguar conservation in Mexico. We worked with the Mexican government to implement the conservation strategy and then evaluated its effectivity. To compare the 2010 and 2018 results, we estimated the amount of jaguar-suitable habitat in the entire country based on an ecological niche model for both periods. Suitable jaguar habitat covered ~267,063 km2(13.9% of the country’s territory) in 2010 and ~ 288,890 km2(~14.8% of the country’s territory) in 2018. Using the most conservative density values for each priority region, we estimated jaguar densities for both the high and low suitable habitats. The total jaguar population was estimated in ~4,000 individuals for 2010 census and ~4,800 for the 2018 census. The Yucatan Peninsula was the region with the largest population, around 2000 jaguars, in both censuses. Our promising results indicate that the actions we proposed in the National Jaguar Conservation Strategy, some of which have been implemented working together with the Federal Government, other NGO’s, and land owners, are improving jaguar conservation in Mexico. The continuation of surveys and monitoring programs of the jaguar populations in Mexico will provide accurate information to design and implement effective, science-based conservation measures to try to ensure that robust jaguar populations remain a permanent fixture of Mexico’s natural heritage.

© 2018 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 wellbeing. We describe an ongoing effort by the Environment Working Group (EWG), created by The University of California's UC-Mexico initiative in 2015, to promote binational research, teaching, and outreach collaborations on the implications of climate change for Mexico and California. We synthesize current knowledge about the most pressing issues related to climate change in the US-Mexico border region and provide examples of cross-border discoveries and research initiatives, highlighting the need to move forward in six broad rubrics. This and similar binational cooperation efforts can lead to improved living standards, generate a collaborative mindset among participating universities, and create an international network to address urgent sustainability challenges affecting both countries.

Thermal ecology studies of ectothermic organisms provide important information for studying ecological physiology, evolution, behavior, and more recently, to assess how climate change may affect them. Ectotherms have received wide attention, but field studies on amphibians are lacking. Consequently, we present data on thermoregulation of 11 species of amphibians from Nayarit, western Mexico. The results are discussed with thermally similar strategies. Our results fill some existing knowledge gaps of amphibian thermal ecology and provide the framework for future research on the eco-physiology of ectotherms.

A new species of hylid frog is described from the southwestern edge of the Mexican Plateau from the states of Morelos and Mexico through Michoacan and Jalisco, reaching the Sierra Madre Occidental in Sinaloa and western Durango. The new species is part of the widespread Mexican hylid Sarcohyla bistincta ( sensu amplo ) complex, comprised of S. bistincta , S. pentheter , S. calthula , and S. ephemera . One subspecies of S. bistincta ( labeculata ) was proposed for an isolated population in Oaxaca. We restrict the group’s nominal species, S. bistincta ( sensu stricto ), to the Sierra Madre Oriental of Mexico and southward into the Sierra Madre del Sur of Guerrero and Oaxaca. Examination of type material places S. calthula and S. ephemera in the synonymy of S. labeculata (new combination). The species allied to S. bistincta, namely , S. bistincta , S. labeculata , S. pentheter , and the new species described herein, are diagnosed and described following recent suggested taxonomic changes and new available material.

Natural Protected Areas (NPAs) includes important species richness, and it is assumed that these are the best areas for biodiversity conservation. There are certain doubts, however, about the effectiveness of the NPAs in developing countries, where economic resources for conservation are scarce and NPAs are not monitored and managed efficiently. In the present study we assessed the species richness, diversity, abundance, and functional guilds of amphibians and reptiles inside and outside of the NPA Reserva Estatal de la Biósfera Sierra San Juan (REBSSJ), Nayarit, Mexico. Our results showed that species numbers of amphibian and reptiles were higher outside than inside the reserve, as well the individual number distributed among species, except for lizard species. Analyses of functional guilds showed that both richness and functional dispersion were greater in amphibians and reptiles outside the reserve. Likewise, outside the reserve we recorded a higher species number with some category of risk at the national level (NOM-059), international level (IUCN), and also by using the Environmental Vulnerability Score (EVS) algorithm. The results suggest that areas outside of the reserve are crucial to the maintenance of regional biodiversity, due to high complementarity with species composition inside of the reserves. These data can be used to implement conservation measures that include a new demarcation of the reserve and the consideration of surrounding areas to include a great number of species.

ResumenEn febrero de 2019 se fotografió con cámaras trampa un ejemplar de zorra gris (Urocyon cinereoargenteus) 2.4 kilómetros al sur de Los Corchos, Municipio de Santiago Ixcuintla, Nayarit, México. Este representa el primer registro de zorra gris en el municipio de Santiago Ixcuintla y el segundo en la llanura costera del Pacífico de Nayarit, lo que extiende su distribución 88 km al sur del registro de Tecuala y a 48 km al norte de San Blas, Nayarit.Palabras clave: carnivora, fototrampeo, llanura costera del Pacífico, Nayarit, Urocyon cinereoargenteus.AbstractIn February 2019, a specimen of gray fox (Urocyon cinereoargenteus) was photographed with camera traps 2.4 kilometers south of Los Corchos, Municipality of Santiago Ixcuintla, Nayarit, Mexico. This represents the first record of the gray fox for the Municipality of Santiago Ixcuintla and the second for the Pacific coastal plain of Nayarit, extending its distribution 88 km south of record from Tecuala and 48 km north of San Blas, Nayarit.Key words: camera trapping, carnivora, Nayarit, Pacific coastal plain, Urocyon cinereoargenteus.

ResumenDe las seis especies de felinos silvestres que habitan en México, es del margay o tigrillo (Leopardus wiedii) una de las que menos información se tiene. En Nayarit no se cuenta con información detallada de su distribución a nivel estatal, encontrando únicamente dos registros para esta especie. Como parte de un muestreo piloto utilizando cámaras trampa en el parque natural La Montaña Encantada, Municipio de Xalisco, Nayarit, se obtuvieron cuatro registros de margay. Una fotografía se tomó en un arroyo en una selva mediana subcaducifolia, mientras que los tres restantes se obtuvieron en un camino de terracería de un bosque de latifoliadas, camino que también fue utilizado por personas a pie y en vehículo. Tres de las cuatro imágenes corresponden al mismo individuo, mientras que la cuarta no pudo ser identificada por ser del costado izquierdo del organismo. Además por la pérdida del hábitat natural, se detectaron gatos y perros ferales, lo que representa un peligro para la permanencia de esta especie en la zona. Los registros del presente trabajo confirman la presencia del margay en el estado y constituye el primer registro para el municipio de Xalisco, ampliando su distribución conocida 83.7 km suroeste y 43.7 km sureste de los registros previos.Palabras clave: carnívoros, felinos, Nayarit, margay.AbstractOf the six species of wild cats that inhabit Mexico, it is the margay or tigrillo (Leopardus wiedii) one of the least information available. In Nayarit, there is no information on its distribution at the state level with only two records for this species. As part of a pilot study in La Montaña Encantada natural park, municipality of Xalisco, Nayarit, four records of margay were obtained. One photograph was obtained in a dry stream surrounded by tropical deciduous forest, while the other three were taken on a dirt road from an oak forest. This road was also used by people on foot and by vehicle. Three of the four images corresponded to the same individual, while the fourth could not be identified because the picture shows the left side of the organism. In addition to the loss of natural habitat, feral cats and dogs were detected, which represents a danger for the permanence of this species in the area. The records of this work confirm the presence of the margay in the state, represents the first record for the Municipality of Xalisco, and extend its known distribution 83.7 km to the southwest and 43.7 km to the southeast of the previous records.Key words: carnivores, felines, Nayarit, margay.

ResumenSe presenta información sobre presas consumidas por la culebra de agua Thamnophis hammondii en un arroyo de montaña en Baja California Sur, México. Esta culebra incluye en su dieta a la rana arborícola de Baja California Pseudacris hypochondriaca curta (especie nativa), pero también a un pez exótico: la tilapia de vientre rojo Tilapia sp. cf. zilli. Este pez introducido en los oasis de Baja California Sur ha desplazado a las especies de peces nativos, y a la vez se ha convertido en un recurso alimentario importante para T. hammondii.AbstractInformation is presented about the prey consumed by the two-stripped garter snake Thamnophis hammondii in a mountain oasis in Baja California Sur, Mexico. The diet of this threatened snake includes the Baja California treefrog Pseudacris hypochondriaca curta (native species), as well as an exotic fish: the red bellied tilapia Tilapia sp. cf. zilli. This exotic species has become invasive in Baja California Sur oases, displacing native fishes and becoming an important dietary resource to T. hammondii.

Background Monitoring of animal populations is critical for proper management. To have a better understanding of the population dynamics and migratory pattern of the whale shark, data is required from locations close to key aggregation sites where hypothesized connections can be validated. Photo-ID is an effective marker for capture-mark-recapture studies. Underwater photographs of sharks, combined with photo-comparison software, are used to identify re-sighted sharks, which, in turn, contribute to estimations of population size, age structure, sex ratio, site fidelity, trends in abundance, and movement patterns Approach Since 2003 we have established and maintained a photographic identification research program in the Gulf of California, at Los Angeles Bay (LAB), La Paz Bay (LPB), Espiritu Santo Island (ESI) and Los Cabos (LC), and since 2010 at the Archipelago of Revillagigedo (AR, at the Mexican Pacific). Recently, we included Nayarit (Na, in the Mexican Pacific) to the study area, San Luis Gonzaga (SLG) and Coyote Bay (CB, Gulf of California) in order to address if connectivity exists in this region. Results The whale sharks appear to segregate by size. In coastal waters of LAB (n=501), LPB (n=380), SLG (n=51), Na (n=36), and CB (n=16) aggregations are exclusively juvenile sharks (9 m) aggregate. At AR (n=11) both pregnant females and juveniles exist but are separated by time. From 2003 to 2014 we have identified 898 sharks over the course of the study; of these 841 were juveniles and 57 were adults, mainly pregnant females. Photo-identification showed the movements of 133 juvenile sharks between LAB, LPB, SLG, Na and CB and movement of 2 pregnant females between LC and AR. We found high levels of fidelity in the juveniles. For example in LPB up to 61% of the juveniles have been re-sighted between years. In contrast only one pregnant female has been re-sighted at the same locality after 7 years. Conclusions This study demonstrated the importance of a collaborative effort to have a better understanding of the population on a regional level. The connectivity data showed the necessity to generate a regional conservation strategy; of the eight localities where we study these gentle giants, currently three are protected, the other four require protection.

The chytrid fungus Batrachochytrium dendrobatidis was detected in five populations of Pseudacris hypochondriaca curta, an endemic treefrog fully dependent on desert oases in Baja California Sur, Mexico. Prevalence of the fungus varied among oases with values of 8, 31, 42, 60, and 100% for populations sampled. Oases with higher prevalence were inhabited by exotic species such as American bullfrogs (Lithobates catesbeianus) and crayfish (Procambarus clarkii). These observations are the first of B. dendrobatidis in amphibians from lowland (

The American bullfrog (Lithobates catesbeianus), considered as one of the world’s worst invasive species because of its negative effects on native fauna, has been introduced into over 40 countries in four continents. The invasion status in Mexico is poorly known. The first known record for this species in the Peninsula of Baja California, northwestern Mexico is an individual collected 35 years ago. A great portion of the peninsula is an arid desert where the sources of freshwater are the spring-fed oasis and mountain arroyos that support rare and endemic species closely associated with wetland conditions. Humans, who have introduced alien species, inhabit many of those oases. The aim of this work was to document the presence of the exotic bullfrog in 40 oases and mountain arroyos in Baja California Sur state during 2006–2009. Bullfrogs were found in 25% of the oases sampled; 15% have confirmed records of breeding populations and five oases are new location records. Our results show a considerable increase (50%) in the number of oasis invaded by bullfrogs in only 8 years. The animal populations of rare or endemic species associated with oases would be threatened by the arrival of bullfrogs. Actions for their control and eradication are urgently needed.

A widely accepted biodiversity crisis in the tropics has been recently challenged by claims that secondary forests will gradually restore biodiversity losses. This prediction was examined for the herpetofauna in Quintana Roo, Mexico. Quantitative sampling (108 transects) of reptiles was undertaken monthly (January-September 2004) along a vegetation gradient covering induced grasslands, and regrowth and primary rain forests. A total of 35 species was found, 14 being present in and five showing dependence on mature forests. Lizards contributed > 90 per cent of the individuals observed. Reptile abundance and snake species richness was highest in primary forests, even though the lower abundance and richness did not differ between regrowth forest and induced grasslands. Multivariate ordinations and ANOSIM tests displayed clear differences in assemblage structure among vegetation types, mainly caused by contrasting abundances of lizard species having distinctive arboreal or terrestrial habits. There was no evidence that snake assemblages differed between secondary forests and induced grasslands. Microhabitat availability had a key role in shaping species composition through the vegetation gradient. Our results dismiss the hypothesis that secondary forests can act as reservoirs of primary forest reptile diversity on the basis that many taxa depend largely on habitat quality and have specialized life-history traits, and that biological succession does not guarantee the recovery of assemblage complexity.

Male and female reproductive cycles are described for Sceloporus melanorhinus in Chamela, Jalisco, Mexico. Both males and females reached sexual maturity at 62 mm snout–vent length. Testes mass of adult males began to increase in March, reached maximum size in July, and began to decrease in August and September, reaching minimum size in October and November. Testes size was associated with increasing photoperiod, but not with temperature or precipitation. Enlarged vitellogenic follicles first appeared in May, and oviductal eggs were found from June to September. Vitellogenesis, follicular growth, and egg production were correlated with increasing photoperiod, temperature, and precipitation. Females produced a single clutch during the reproductive season. Mean clutch size based on oviductal eggs was 7.7 (range = 5 to 9). Clutch size was not correlated with female snout–vent length.

The jaguar (Panthera onca) is one of the most endangered felids in the world. Its distribution has been reduced by 50% globally, and the species continues to be hunted illegally. We provide data on jaguar abundance, sex ratio, seasonal and daily activity, and site fidelity in La Papalota—a 368-ha natural protected area in Nayarit, western Mexico. La Papalota is located between two areas with high priority for the conservation of the jaguar: Marismas Nacionales Biosphere Reserve and the San Blas-San Juan area. Over a period of 4,240 trap nights (14 months), we collected 130 independent photos of six different individuals (one adult male, three adult females, one subadult female, and one cub). Jaguars use La Papalota all year round, and we were able to document three pregnancies. We suggest that, although a small protected area like our study site cannot provide an entire home range for even a single jaguar, it and similar reserves can play a crucial role as stepping-stones for jaguars moving across highly ...

Nayarit is one of the Mexican states where less has been published regarding the fauna of amphibians. The aim of this work was to generate a list of amphibians of Nayarit through literature review and fieldwork. The amphibian fauna of Nayarit consists of 37 species, belonging to 21 genera, 10 families, and two orders. Among these 37 species, 36 are native, 21 are endemic to Mexico, and one is exotic (the American bullfrog Lithobates catesbeianus). In total, nine species are under the category of “Special Protection” and one as “Endangered” by Mexican laws and four (one as “Endangered” and three as “Vulnerable”) under international laws of protection. In the near future, our expectation is that more species will be added to the list of species of amphibians in Nayarit, as more fieldwork remains to be done in some remote and unexplored areas of the state.

The frequency of cyclonic storms that generate severe modification of a mountain arroyo ecosystem appears to have served as a selective pressure on native treefrogs resulting in a specific behavior to avoid the negative effects of the floodwaters. Apparently exotic bullfrogs found here lack this evolutionary response because during cyclonic rains they continue their activity and die by being dragged by the heavy water flow. Based on field observations, we propose recommendations for future well-designed studies to explore the role of tropical cyclones as sources of natural selection on native and exotic species exposed to these natural phenomena.