The Vaquita (Phocoena sinus) is a porpoise endemic to the Upper Gulf of California (UGC), a region significantly impacted by the damming of the Colorado River. This study investigated whether the Vaquita inhabited and fed in waters influenced by the river during high-flow periods (than >500 m(3)yr(-1)) between 1983 and 1987. We analyzed delta C-13 and delta O-18 time series from dentin (n = 7) and compared these with satellite data on temperature, salinity, and river flow across three periods: prerelease (1976-1982), release (1983-1987), and postrelease (1988-2017). Significant differences in delta C-13 values were probably related to changes in carbon sources or prey availability. While mean delta O-18 values remained consistent across periods, intra-individual data revealed two key findings. First, the highest variability occurred during the prerelease period despite sub-maximal river flow. This period also recorded the lowest sea surface salinity and temperature, suggesting that delta O-18 values were influenced by environmental variables independent of those studied here. Second, prenatal layers exhibited higher isotopic values than other growth layers, indicating a maternal diet relying on local prey rather than fat reserve catabolism, making the species particularly susceptible to environmental changes during breeding. Compared to other marine mammals from the southern Gulf and the Pacific, the Vaquita showed the highest delta C-13 and delta O-18 values, reflecting the extreme evaporation and hypersalinity of the UGC. Given its critical status and restricted habitat, understanding the Vaquita's ecology and its response to environmental variability is essential for its conservation.

The dynamics of climatic conditions cause diverse changes in organisms’ populations. Species as the kangaroo rats (Dipodomys) have shown sensitivity to some climatic conditions variables such as the precipitation and temperature. For this reason, it is important to understand the relationship between these conditions and species, especially when Dipodomys species are considered keystone species and ecosystem engineers. The capture-recapture technique was performed monthly from 2012 to 2016. Total individual counts, age, reproductive condition, weight, and sex of Dipodomys merriami and D. nelsoni were determined and recorded. We analyzed the frequencies, age, reproductive status, sex ratio, and weight of sampled species. Daily temperature and precipitation data of the study area were analyzed with population parameters and frequency data. Further, temperature and precipitation from 2012 to 2016 in the study area were analyzed in regard with studied species frequencies. The research was conducted in two environments: shrubland and grassland in the Chihuahuan desert. The results showed that D. merriami was the most abundant species; however, the frequencies from the two species were higher in the shrubland. Moreover, there was no statistic relationship between species’ frequencies and temperature, but there was a tendency with precipitation. Overall, the number of males and females of the two species was similar. The most found age category individuals was adults, most frequent reproductive status were non-pregnant females and males with abdominal testicles. Weight of individuals was different between species and age categories sub-adults and adults. The patterns are comparable to those found in other species of this genus. Results from this research provide information needed to take the required actions regarding the management and conservation of species with restricted distribution, such as D. nelsoni.

The vaquita (Phocoena sinus) is an endemic species of the Upper Gulf of California (UGC), which is in a critical state of extinction. Bycatch has been considered the main factor leading to its potential extinction; however, the impact of the damming of the Colorado River on the species' ecology has not been studied. Stable isotopes of carbon (delta C-13) and oxygen (delta O-18) from vaquita bones were analyzed as indicators of the carbon source of primary producers and habitat use in the UGC from 1982 to 1993. Based on the Colorado River's flow into the UGC, two periods were markedly different: from 1982 to 1988, when freshwater arrived, and from 1989 to 1993, when the flow was null. Sea surface salinity (SSS) data showed the inverse of the river's flow pattern, being significantly lower at the end of the 1980s than at the beginning of the 1990s. In agreement with the above, sea surface temperature (SST)/SSS diagrams showed the presence of two water masses inside a gradient from 33.8 to 35.2 psu. The delta C-13 was significantly different between both periods, with a mean value of -9.1 parts per thousand at the end of the 1980s and a mean value of -10.8 parts per thousand at the beginning of the 1990s. This means that, when the river flow was dammed, the carbon source of primary producers changed significantly in the UGC. However, the delta O-18 was not significantly different between both periods, with values of 30.4 parts per thousand and 30.5 parts per thousand, respectively. Comparing the vaquita's average values of delta O-18 from this study with those of other marine mammals obtained from previous studies revealed that the vaquita is the most enriched marine mammal species, which could be the result of the high evaporation and salinity that currently occur in the UGC, the vaquita's habitat. A longer temporal series might show changes in delta O-18, which have been detected in other species living in the UGC. From a conservation point of view, the results showed that the impact of environmental variability on the trophic ecology of the vaquita has potential effects on the species' health.

In the Reserva Ecológica del Pedregal of San Ángel, located in the south of Mexico City, Mexico, free-roaming dogs and cats coexist with 148 bird, 33 of mammal, 23 of reptile and seven amphibian species, that represent a remnant of the original fauna of the Mexican Plateau. The negative impact that dogs and cats have on local fauna is unobjectionable, however, the role that these introduced vertebrates play as potential transmitters of infectious diseases for native fauna and humans, is much less understood. Information about parasitic infections in native and introduced animals in this location is scarce. In order to ameliorate this lack of information, the objective of this study is to characterize the helminth fauna of the free-ranging dogs and cats of the ecological reserve. Between 2018 and 2023, 36 Felis silvestris catus and 7 Canis lupus familiaris were studied from the helminthological perspective. Endoparasites were obtained from the digestive tract and were identified to the species level using morphological and molecular evidence. Hosts were parasitized by eight species of helminths: in cats the cestodes Hydatigera taeniaeformis, Mesocestoides sp., Taenia rileyi and the nematode Toxocara cati were recorded, while in dogs, the cestode Taenia pisiformis and the nematodes Ancylostoma caninum, and Uncinaria stenocephala were found. The only species shared between cats and dogs was the cestode Dipylidium caninum. These free-ranging animals act as definitive hosts of 5 species known to have zoonotic potential; their presence in the area may generate a public and animal health problem if programs of dog and cat population control are not continued.

This database compiles comprehensive occurrence information, based on voucher specimens of small-eared shrews, genus Cryptotis, that occur from México to Peru. The database integrates the information obtained from four main sources: natural history museums, public databases, fieldwork and scientific literature. It contains 3,639 records from 53 species in 12 countries. Of the total, 83.54% have collecting dates, 51.36% of the specimens are sexed and 84.56% have decimal degrees coordinates. By generating this database and making it publicly available, we hope to improve the biological knowledge of this group of small mammals still poorly studied in the region. It aims to be a valuable resource for students, researchers, conservationists and decision-makers. The dataset contains information on all species of the genus Cryptotis in the Neotropical Region (namely from México to Peru), incorporating the most updated taxonomic and nomenclatural changes. The database includes records in regions and countries that are poorly represented in currently available data repositories. Most records have verified temporal and spatial information.

El tlacuache ratón de Yucatán (Tlacuatzin gaumeri) es una especie poco conocida hasta ahora, reportada solamente de los estados mexicanos de Campeche y Yucatán en la Península de Yucatán. En virtud de la vecindad geográfica de estas entidades con el estado de Quintana Roo y por su similitud climática y de vegetación, se esperaría la presencia de este marsupial en territorio quintanarroense. Se consultaron la literatura científica, los registros curatoriales de colecciones científicas en México, en el GBIF y las observaciones del portal de ciencia ciudadana iNaturalistMX. Los registros curatoriales y una observación de campo se ordenaron en una tabla y se elaboró un mapa con QGIS 3.36.2. Se encontraron registros curatoriales de colección científica de T. gaumeri para el estado mexicano de Quintana Roo. Similarmente, se encontró una observación (grado investigación) de ciencia ciudadana para Quintana Roo, cerca de la porción occidental de la Reserva de la Biosfera de Sian Ka’an. Los registros amplían la distribución geográfica conocida de T. gaumeri 139 km (en promedio) hacia el este de la Península Yucateca. Los datos registran por primera vez a T. gaumeri en Quintana Roo y confirman su endemicidad en ese estado; asimismo amplían la distribución geográfica conocida de este marsupial. Aunque su presencia coincide solo con un área natural protegida, puede contribuir a su conservación. Se requiere todavía determinar si aplica para alguna categoría de riesgo, pero los resultados contribuyen al inventario faunístico de la Península Yucateca.

Lepus altamirae es una liebre poco conocida del noreste de México. Recientemente se restableció su validez taxonómica y se alertó sobre la ausencia de sus registros de campo. Se redescubrió recientemente, pero desconocemos su distribución geográfica completa y si sobrevive en su localidad tipo. Este estudio pretende confirmar su presencia en su localidad tipo y contribuir con recomendaciones para su supervivencia. Buscamos liebres en caminos y brechas utilizando un carro y caminando en áreas naturales y perturbadas en Altamira y sus alrededores de junio a agosto de 2020. Anotamos los registros visuales de las liebres encontradas y pedimos permiso a cetreros encontrados casualmente para usar sus datos de captura de liebres. Confirmamos la identificación taxonómica de las liebres con referencias especializadas. No encontramos liebres en la localidad tipo, cuyo habitat ya se encuentra degradado, pero registramos visualmente ejemplares en las inmediaciones de Altamira. Asimismo, encontramos registros adicionales de L. altamirae en la literatura científica y en un portal de ciencia ciudadana que muestran localidades donde previamente se desconocía su presencia en distintas direcciones geográficas de la localidad tipo, incluyendo el estado de Veracruz. Lepus altamirae ya no existe en su localidad tipo, en donde se ha incrementado su nivel de urbanización. Sin embargo, se sabe de su presencia en áreas que incrementan su distribución geográfica previamente conocida. Se requiere continuar explorando su distribución potencial para proponer medidas apropiadas para su conservación, además de promover la inclusión de su nombre en las listas de mamíferos mexicanos.

Diet analysis was performed on free ranging cats (Felis silvestris catus) and dogs (Canis lupus familiaris) from Reserva Ecologica del Pedregal de San angel (REPSA), Ciudad Universitaria, UNAM, Mexico City. Twelve samples of cats and 55 of dogs were analyzed as part of the Wildlife Remediation Program of the REPSA's Executive Secretariat. The determination of consumed species was made by comparing the obtained remains with specimens deposited in scientific collections; additionally, for mammals, morphological scales patterns and hair marrow were examined. Our results showed that the diet of cats and dogs is mainly composed of medium-size mammals (Bassariscus astutus, Didelphis virginiana, Otospermophilus variegatus, Spilogale angustifrons, and Sylvilagus floridanus) and small mammals (Mus musculus, Neotoma mexicana, Peromyscus gratus, Rattus norvegicus, Reithrodontomys fulvescens, and Sorex saussurei), with a smaller proportion of reptiles and insects and food material for human consumption. The native mammals are consumed more than introduced mammals, and that diet of cats and dogs includes species endemic to Mexico (S. saussurei, P. gratus, and Peromyscus melanophrys) or in any risk category (S. saussurei and the lizard Sceloporus grammicus). These results provide information for justify and developing conservation alternatives in urban ecological reserves.

Se analizó la dieta de gatos (Felis silvestris catus) y perros (Canis lupus familiaris) errantes de la Reserva Ecológica del Pedregal de San Ángel (REPSA), Ciudad Universitaria, UNAM, Ciudad de México. Se examinaron 12 muestras de gatos y 55 de perros obtenidas mediante el Programa de Remediación de Fauna Feral, Secretaría Ejecutiva de la REPSA. La determinación de las especies consumidas se realizó comparando el material con ejemplares depositados en colecciones científicas; adicionalmente para mamíferos, se utilizaron patrones morfológicos de la cutícula y médula del pelo. El análisis mostró que la dieta de gatos y perros está compuesta, principalmente, de mamíferos medianos (Bassariscus astutus, Didelphis virginiana, Otospermophilus variegatus, Spilogale angustifrons y Sylvilagus floridanus) y pequeños (Mus musculus, Neotoma mexicana, Peromyscus gratus, Rattus norvegicus, Reithrodontomys fulvescens y Sorex saussurei), en menor proporción de reptiles e insectos, y material alimenticio de consumo humano. Los mamíferos nativos son más consumidos que los introducidos y que la dieta de gatos y perros incluye especies endémicas de México (S. saussurei, P. gratus y Peromyscus melanophrys) o en alguna categoría de riesgo (S. saussurei y la lagartija Sceloporus grammicus). Estos resultados proveen información para justificar y desarrollar alternativas de conservación en reservas ecológicas urbanas.

CorrigendumMontero-Bagatella, S. H., F. A. Cervantes, and A. González-Romero. 2023. Population parameters of the Phillips kangaroo rat (Dipodomys phillipsii). Therya 14:351-359.Change in:Figure 3. Average sex and age breakdowns of captured Phillipsi kangaroo rat (Dipodomys phillipsii) by season for 2012-2016, from Perote, Veracruz.

¿Cuáles son las ventajas o desventajas para un tlacuache de vivir en una zona urbana? ¿Qué funciones desempeña en este tipo de lugar? ¿Sabías que una especie de tlacuache habita dentro del campus universitario de la UNAM?

Genetic studies in the highlands of Mexico have revealed extensive intraspecific differentiation and highly structured genetic variation in rodents and other taxa. One of the most important and complex systems in these highlands is the Trans-Mexican Volcanic Belt (TMVB), a biogeographic region located in central Mexico. Recent studies suggest strong structure and undiscovered diversity within the TMVB highlands, which indicates more study of endemic species is warranted. One of these species is the endemic Volcano Harvest Mouse Reithrodontomys chrysopsis, which inhabits small and fragmented patches at high altitudes. This mouse is poorly known, under-represented in field collections, and has been the subject of few studies of phylogenetics, taxonomy, and evolutionary history. This study aimed to assess the phylogenetic and intraspecific relationships of R. chrysopsis throughout its known geographic distribution to better understand the evolutionary patterns of it and other TMVB mammals. Our phylogenetic analyses using Cytb and Fgb-I7 markers revealed that R. chrysopsis is sister to R. sumichrasti and R. megalotis, which contrasts with a previous hypothesis based on morphological data. Genetic differentiation, divergence time, and species delimitation analyses showed three main divergent lineages within R. chrysopsis, located at the western, central, and eastern TMVB. These lineages diverged during the Pliocene-Pleistocene interval. Our results support the hypothesis that volcanic activity and climatic oscillations during the Pleistocene in central Mexico promoted diversification processes within the TMVB. Further molecular and morphological studies will be needed to provide information for the taxonomic designation of the east divergent lineage detected herein.

La Universidad Nacional Autónoma de México (unam) implementó en 2013 un sistema de separación de Residuos Sólidos Urbanos (rsu) en Ciudad Universitaria, para reducir el impacto ecológico. Sin embargo, algunos mamíferos silvestres como los tlacuaches (Didelphis virginiana), que habitan en la Reserva Ecológica del Pedregal de San Ángel (repsa) y las áreas verdes circundantes, que cuentan con pedregales remanentes, quedan atrapados dentro de los contenedores de basura al ir en busca de alimento. Sin ayuda de alguna persona pueden morir, pues como los botes son profundos y lisos, no pueden salir. Este solo es uno más de los retos de supervivencia a los que se enfrenta la fauna silvestre, A pesar de información que ha sido difundida en redes sociales, así como propuestas para ayudarlos, esta problemática sigue siendo desconocida para la mayoría de la comunidad universitaria. Así, en este trabajo se proponen acciones para saber qué hacer en caso de que un tlacuache sea encontrado en un bote de basura, con el propósito de contribuir a la conservación de este animal poco comprendido.

Populations respond dynamically to biotic and abiotic changes in their habitat. The identification and description of such demographic oscillation can inform conservation plans that support threatened species. Human activities have reduced and fragmented the already restricted habitat of the Phillips's kangaroo rat ( Dipodomys phillipsii) , threatening its existence. The objective of this study was to describe and analyze D. phillipsii ’s annual population cycle and structure in the context of its increasing vulnerability to extinction. The capture-recapture technique was performed monthly from 2012 to 2016. Total individual counts, age, reproductive condition, weight, and sex of D. phillipsii were determined and recorded. Daily temperature and precipitation data of the study area were analyzed with population parameters and frequency data. D. phillipsii populations responded to changes in temperature and precipitation. The highest population densities were recorded in the spring and summer and were correlated with the highest values of the environmental variables studied. Sex ratio was nearly equal during samplings, with non-pregnant females and males with abdominal testes as the most frequently presented secondary sexual characteristics. Most captured individuals were adults. Individual body weights were highly variable, which can be attributed to reproduction and fluctuations in resource availability. D. phillipsii populations severely decreased in the last year of the study, with low juvenile and pregnant or lactating female frequency counts. Anthropogenic pressures on D. phillipsii habitat persist, indicating that the proliferation of this species is at risk. Information from this study could be used to address the pressing need for the management and conservation of D. phillipsii.

Each species displays a certain level of social tolerance. However, within a species, individuals show differences in their ability to accept the presence of conspecifics around resources of mutual interest. Social structure research allows studying how social relationships arise within a group, how they survive or end through time, and how they are influenced by various factors such group composition, mating system, and habitat quality variations. Furthermore, it can help elucidate the tolerance of individuals to other group members and how changes in it may lead to changes in social stability. Social Network Analysis (SNA) is a tool that allows the assessment of social dynamics and interactions. Our goal was to evaluate and compare social tolerance in captive spider monkeys ( Ateles geoffroyi ) by examining social networks formed in social groups that varied in size and composition. We compared social networks of captive groups varying in sex ratio, group size, and age ratio. Results showed relationship between networks with similar size and composition. Smaller groups showed greater social distancing, while larger ones displayed shorter inter-individual distances and more affiliation. Agonism was infrequent in unisexual groups compared to groups formed by both sexes. Finally, groups with more males showed greater social distancing and greater agonism. Overall, largest groups (five members or more) and similar sex ratio (or unisexual) are better connected. Largest groups showed higher proximity levels and a more tolerance to conspecifics than small groups.

The small-eared shrews Cryptotis mexicanus and Cryptotis obscurus (Eulipotyphla, Soricidae) are two closely related taxa from the northern Neotropics whose taxonomy is still unresolved. Here, we tested the hypothesis of three lineages (Northern, Central, and Southern) within this pair of semifossorial shrews. We photographed skulls, dentaries, and humeri from 226 museum specimens and used geometric morphometrics to evaluate sexual dimorphism, differences between lineages, and the effect of the environment on the shape of the structures. We found negligible differences between males and females, supporting previous studies of classical morphometrics in this genus. Our results also support the differentiation of semifossorial shrews into the three geographically isolated groups, where the size of the dentary and the shape of the three examined structures contribute to discrimination. We found a significant sign of the influence of the environment on the shape of the dentary but not on the skull or the humerus. We suggest that geographic isolation across climatically similar regions has contributed to the differentiation between lineages. We propose recognizing all three lineages as valid species that must be adequately described.

Conservation of natural ecosystems embedded in urban contexts is a big challenge because diverse anthropogenic factors continuously impact native biodiversity and ecological processes. One such factor is the pervasive presence of free-ranging predators, especially cats ( Felis silvestris catus ) and dogs ( Canis lupus familiaris ), which may severely affect local wildlife. The “Reserva Ecológica del Pedregal de San Ángel” (REPSA), located within the main campus of the Universidad Nacional Autónoma de México (UNAM), in southern Mexico City, is an important natural area that protects a peculiar volcanic spill ecosystem holding native and endemic biodiversity. In 2012, UNAM launched a control program of cats and dogs in REPSA that is still active. To assess the potential impact of cats and dogs on wildlife species, we used live and camera traps coupled with capture-recapture analyses to evaluate changes in the vertebrate community, particularly in the presence and abundance of two medium-size native mammals ( Didelphis virginiana and Bassariscus astutus ), before (2008–2009) and during (2017–2019) the control program. Results showed that the abundance of dogs decreased between the two periods, but not so the abundance of cats, whereas the native vertebrate diversity increased from the pre-control stage to the control period. Furthermore, we found a negative, non-significant relationship between the abundance of D. virginiana and that of dogs, and a positive, also non-significant relationship between the presence and abundance of B. astutus with the abundance of dogs. We conclude that the control program of free-ranging predators has been beneficial for the conservation of native vertebrates and recommend its continuation and enhancement.

The Nelson's small-eared shrew (Cryptotis nelsoni) is a mammal at high risk of extinction and endemic to the cloud forest in the mountains of Los Tuxtlas, an isolated volcanic field in eastern Mexico. It is a little-known species that remained unrecorded for over a century. However, recent works have increased the number of museum specimens and tissue samples of C. nelsoni, which we studied here to improve our knowledge of their taxonomy and conservation status. We compared the morphology and DNA barcode sequences of C. nelsoni against its three most closely related species. We also evaluated the possible effect of anthropogenic climate change on this mountain species according to three general circulation models and two scenarios proposed for the year 2050. The results showed that the skull and postcranial variables could easily discriminate C. nelsoni from the other species in terms of body size, to which some distinctive qualitative characteristics related to the width of the snout and the curvature of the humerus also contribute. DNA barcoding also helped identify the shrew species accurately, with a genetic distance of more than 6% from its closest species. The morphological and genetic characteristics highlight the evolutionary distinctiveness of C. nelsoni. Unfortunately, warmer extremes and higher rainfall than today could pose a severe threat to the survival of this shrew for decades to come, even in the most optimistic scenarios.

Los desiertos mexicanos son habitados por las carismáticas ratas canguro. Estos roedores destacan tanto por su diversidad como por los diferentes servicios que brindan a los ecosistemas. Algunas de las especies del grupo están en peligro de extinción debido a las severas transformaciones de su hábitat. En este artículo se abordarán los principales aspectos biológicos y ecológicos de las ratas canguro en México, así como los algunos de los riesgos de conservación a los que se están enfrentando.