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Peromyscus fraterculus (Miller, 1892) is a small rodent commonly called the northern Baja deermouse. Its pelage is dark, the tail is considerably longer than the body, and the number of caudal vertebrae ranges from 30 to 34. The geographic distribution of P. fraterculus includes the area west of the Colorado River, from southern California in the United States of America southward to the Baja California Peninsula, Mexico, south of La Paz Isthmus. It is found in a broad variety of habitats from sea level to 1,175 m. P. fraterculus does not have special conservation status, although the island populations have conservation issues, mainly due to the introduction of non-native species. It is listed as “Least Concern” (LC) by the International Union for Conservation of Nature and Natural Resources.

Scapanus latimanus is a species with many morphological differences among its populations. This variation is associated with multiple taxonomic changes at the species or subspecies level. This study incorporates genetic analyses and comparisons with previous morphological studies to propose a better understanding of the latimanus complex. Mitochondrial markers (cytochrome b; cytochrome c oxidase subunit I; and cytochrome c oxidase subunit III) were sequenced to construct a phylogeny for the subfamily Scalopinae in North America. Genetic distances ranged from 2.49 to 10.50 % among geographic areas. Results identified three monophyletic clades with high bootstrap support values. Based on our phylogenetic analysis and previous morphological analyses, we confirm S. anthonyi from San Pedro Mártir as a valid species and propose that S. occultus from southern California and northern Baja California peninsula be considered as a species

Migratory species that cross geopolitical boundaries pose challenges for conservation planning because threats may vary across a species’ range and multi-country collaboration is required to implement conservation action plans. The lesser long-nosed bat (Leptonycteris yerbabuenae) is a migratory pollinator bat that was removed from the Endangered Species List in the United States in 2018 and from threatened status in Mexico in 2013. The seasonal ecology and conservation status of the species is well understood in the core part of its range on mainland Mexico and in the southwestern United States, but relatively little is known about the species on the Baja California peninsula in northwestern Mexico, a part of its range range separated by the Gulf of California. We studied the seasonal ecology of lesser long-nosed bats on the Baja peninsula at 8 focal roosts along a 450-km north-to-south transect to test hypotheses about migratory or residential status of the species on the Baja peninsula. We provide evidence of an extensive population of lesser long-nosed bats on the Baja peninsula that is primarily seasonally migratory and includes 2 mating roosts with males on the southern part of the peninsula. Seasonal ecology of lesser long-nosed bats was closely associated with the flowering and fruiting season of the cardón (Pachycereus pringlei), the dominant columnar cactus on the peninsula. However, we discovered that some female lesser long-nosed bats arrive and give birth at southern roosts in mid-February, about 2 months earlier than other migratory populations in more northern Sonoran Desert habitats. We documented the loss of nearly a third of the known maternity roosts during the study, demonstrating that action to protect key roosts remains a high priority. Migratory pollinators are particularly vulnerable to climate and land-use changes and we recommend continued monitoring and research to guide effective range-wide conservation of the species. Las especies migratorias o con rangos de distribución amplios que incluyen fronteras geopolíticas, representan desafíos particulares para la planificación de estrategias de conservación, ya que las amenazas así como las tendencias poblacionales pueden variar a lo largo de su rango geográfico y se requiere la colaboración de múltiples países para implementar planes de acción que permitan su conservación. El murciélago magueyero menor (Leptonycteris yerbabuenae) es un murciélago polinizador migratorio que recientemente fue sacado de la lista de especies en peligro en los Estados Unidos en 2018 y en México en 2013. La ecología estacional y el estatus de conservación de esta especie, ha sido bien estudiado en el centro de su rango de distribución en México continental, pero se sabe muy poco acerca de la especie en la Península de Baja California en el noreste de México, región que está separada del resto del rango por el golfo de California. Nosotros estudiamos la ecología estacional del murciélago magueyero menor, en ocho cuevas a lo largo de un transecto de 450 km norte-sur, en la Península de Baja California y pusimos a prueba la hipótesis del status migratorio o residente de sus poblaciones en esta región. Proporcionamos la primera evidencia de una extensa población de esta especie en la península, a cual es principalmente migratoria estacional e incluye dos cuevas de reproducción ubicadas al sur de esta región. La ecología estacional del murciélago magueyero menor estuvo fuertemente asociada con la estación de floración y fructificación del cardón (Pachycereus pringlei), el cactus columnar dominante en la península. Nosotros también descubrimos que algunas hembras llegan y dan a luz en las cuevas más sureñas, a mediados de febrero, cerca de dos meses antes que otras poblaciones migratorias, en el desierto de Sonora del norte. Durante el tiempo de este estudio, documentamos la destrucción de una de las cuevas de maternidad, lo que demuestra la necesidad de acciones de conservación para proteger estos refugios. Los polinizadores migratorios son particularmente vulnerables a cambios en el uso del suelo y al cambio climático y recomendamos continuar con el monitoreo y la investigación, con el fin de guiar su conservación a lo largo de todo el rango de distribución de la especie.

Bat acoustic libraries are important tools that assemble echolocation calls to allow the comparison and discrimination to confirm species identifications. The Sonozotz project represents the first nation‐wide library of bat echolocation calls for a megadiverse country. It was assembled following a standardized recording protocol that aimed to cover different recording habitats, recording techniques, and call variation inherent to individuals. The Sonozotz project included 69 species of echolocating bats, a high species richness that represents 50% of bat species found in the country. We include recommendations on how the database can be used and how the sampling methods can be potentially replicated in countries with similar environmental and geographic conditions. To our knowledge, this represents the most exhaustive effort to date to document and compile the diversity of bat echolocation calls for a megadiverse country. This database will be useful to address a range of ecological questions including the effects of anthropogenic activities on bat communities through the analysis of bat sound., The Sonozotz project represents the first nation‐wide library of bat echolocation calls for a megadiverse country.

We report the status of alien species on Isla de Cedros, Mexico, and analyze the information from different years that together with a collaborative effort between academic biologists, Mexican governmental agencies, and local individuals has resulted in major information about the alien species on this island. We also report species richness of distinct endemic mammal species and the presence of feral dogs (Canis lupus familiaris Linnaeus), which is the principal problematic situation in this “Marine Priority Region.” The possible origin of feral dogs could be the migratory movement of stray dogs to find food in the inner part of the island, first moving to garbage dumps, reproducing in the area, and later hunting goats (Capra aegagrus hircus Linnaeus) in packs. The combination of the high density of stray dogs, urban and industrial food garbage dumps, and the large number of marine resources scattered along the seashore made ideal conditions for the establishment of feral dog packs that are affecting native species. The island does not have any natural mammal predator, but the presence of feral species, dogs and cats (Felis silvestris catus Schreber), could disturb the occurrence of endemic fauna as it has happened on other islands in the world.

We assessed the current distributions for 2 subspecies of the brush rabbit, Sylvilagus bachmani peninsularis and S. b. exiguus, on the Baja California Peninsula, Mexico. On the basis of field sampling, field notes, and voucher specimens in scientific collections, we demonstrated that (1) both subspecies have been previously recorded in mesic habitats with conditions associated with oases and streams; (2) the 2 subspecies exhibit disjunction in their distributions in the middle and southern portions of the peninsula; (3) habitats are threatened by human activities and desertification, which explains why brush rabbit populations are currently fragmented; and (4) specimens of S. bachmani have not been collected or observed in the last 20 years, with effort concentrated mainly in the southernmost part of the peninsula (San Lucas faunal district). We suggest that S. b. exiguus be considered threatened, requiring immediate conservation actions, including habitat preservation; and we suggest that the southern form, S. b. peninsularis, be considered extinct due to anthropogenic activities.

For over 140 years, the habitat of Socorro Island in the Mexican Pacific has been altered by the presence of exotic sheep. Overgrazing, jointly with tropical storms, has caused soil erosion, and more than 2000 hectares of native vegetation have been lost. Sheep eradication was conducted from 2009 to 2012. Since then, the vegetation has begun to recover passively, modifying soil properties. The objective of our study was to verify that this island was resilient enough to be recovered and in a relatively short time scale. To confirm our hypothesis, we analyzed changes in the physical-chemical properties of the soil and vegetation cover, the last one in different times and habitats after sheep eradication. The change in vegetation cover was estimated by comparing the normalized difference vegetation index (NDVI) between 2008 and 2013. In sites altered by feral sheep, soil compaction was assessed, and soil samples were taken, analyzing pH, electrical conductivity, organic carbon, total nitrogen, phosphorus, calcium, and magnesium. After a year of total sheep eradication, clear indications in the recovery of vegetation cover and improvement of soil quality parameters were observed and confirmed, specifically compaction and nitrogen, organic carbon, phosphorus, and calcium. The results seem to support our hypothesis.

This paper reports the first record of Eumops underwoodi in the Baja California peninsula. This record expands the species' distributional range in Mexico along the peninsula. We propose 2 plausible biogeographical explana- tions. First, the species has the ability to travel across the Gulf of California from the coast of Sonora to the eastern side of the Baja California peninsula and there establish. Second, there is a continuous distribution of the species throughout the mountain ranges that run longitudinally along the Baja California peninsula from the United States border down to the southern tip. We collected one male specimen of E. underwoodi in xeric-riparian habitat. We suggest a continuous distribution pattern of this species along the cliffs in the Baja California peninsula.

Peromyscus eva and Peromyscus fraterculus are 2 morphologically similar species of the Peromyscus eremicus group occurring on the Baja California Peninsula. Due to the similarity between these 2 species, their ranges have been greatly confused; consequently, the specific habitat characteristics for each group are not well known. The goal of this study was to assess distribution ranges and characteristics of preferred habitats for P. eva and P. fraterculus in more detail. We identified taxonomy of individuals by evaluating genetic patterns produced by restriction fragment length polymorphisms (RFLPs). We evaluated the banding pattern generated by Alu I and Bam HI restriction enzymes in an 850-bp cytochrome b fragment. Consistent differences in number and size of fragments allowed for discrimination of individuals to species. The heterogeneity and evenness indexes showed that the microhabitat of P. fraterculus contained less-diverse soil types and is more homogeneous than the microhabitat of P. ev...

We report the first observations of the black-tailed jackrabbit (Lepus californicus) on Cerralvo Island, Baja California Sur, Mexico. Evidence suggests a self-sustaining population. Analysis of available records indicates no previous record of Lepus on the island. Introduction of the jackrabbit to the island appears to have occurred between 1960 and 1991.

Santa Catalina Island has an endemic mouse, Peromyscus slevini, which is the only native rodent species on the island. However, specimens of P. fraterculus have been recorded on the island. P. fraterculus is the most common species of Peromyscus off Santa Catalina Island in the Baja California peninsula. The records show the absence of P. slevini in the 1990s and an increasing number of P. fraterculus during the 2000s. P. slevini has recently been collected in 2007. The current situation in Santa Catalina Island shows a strong expansion of P. fraterculus and the restriction of P. slevini to the canyons. This study confirms for the first time the recent invasion of a peninsular native species in one island on the Gulf of California. Peromyscus fraterculus is a better desert adapted species in contrast to P. slevini. Under those conditions, in the near future, P. slevini could be extinct.

Mysticeti whales modify their calls in response to an increase in noise level within their environment. This is particularly important since environmental noise has been increasing continuously in the last decades. In the case of Bryde's whale (Balaenoptera edeni), previous studies of its predominant call, Be4, have exposed differences in the duration of its main component (f0) for northern and southern areas of the Gulf of California (GC). The objective of this research is to determine if the differences found among Be4 calls (f0, duration, and energy distribution) are influenced by the noise levels in those areas. Results based on the characterization of Be4 Call and noise show that northern noise level is intense in the octave frequency band centered around 30 Hz, and could mask the 30 Hz component. This kind of noise is rare in the south (5%) and when it was present, the 30 Hz component was not registered, which might be an adaptation to noise. Predominant moderate noise in the south within the band 2...

La información actualizada sobre la representatividad geográfica y taxonómica de los ejemplares depositados en 28 colecciones mastozoológicas mexicanas y la disponible en las bases de datos Mammal Networked Information System (MaNIS), y de la Unidad de Informática para la Biodiversidad (UNIBIO) se recopiló con el fin de analizar y comparar el estado actual de los ejemplares de mamíferos mexicanos depositados en colecciones de Norteamérica. Se documentaron un total de 421,466 ejemplares de mamíferos depositados en 120 colecciones mastozoológicas, de los cuales 233,116 ejemplares se encuentran en colecciones de Estados Unidos de América y Canadá, y 188,350 ejemplares en colecciones de México. Las colecciones con el mayor número de ejemplares de mamíferos de México son la Colección Nacional de Mamíferos (CNMA 46,000), la Universidad de Kansas (KU 44,301), y la Escuela Nacional de Ciencias Biológicas (ENCB 43,985). En colecciones mexicanas, los estados del norte de México están escasamente representados en número de ejemplares ( 3,000), y en las colecciones extranjeras, los estados del centro de México están pobremente representados. Los estados mexicanos mejor representados por número de ejemplares ( 10,000) son Baja California Sur, Chiapas, Oaxaca, Puebla y Veracruz. Los órdenes mejor representados por el número de ejemplares son Rodentia y Chiroptera (234,978 y 120,956, respectivamente). Los estados mexicanos con menor extensión territorial tienen la mayor densidad de ejemplares colectados (ejemplares/km 2 ): Distrito Federal (3.2), Tlaxcala (1.4), Colima (1.06) y Morelos (0.9). Se espera contar con una línea base que permita establecer estrategias adecuadas para completar el inventario nacional de los mamíferos mexicanos, y lograr que este patrimonio natural este adecuadamente representado en colecciones de México.

The Baja California rock squirrel (Otospermophilus atricapillus Bryant) is endemic to the Baja California Peninsula, Mexico and known from only five localities. O. atricapillus is considered as the sister species of O. beecheyi (Richardson) and both have been considered different species mainly by its colorations. In an attempt to better understand the relationship within O. atricapillus and with its sister species O. beecheyi, we used genetic information gathered from O. atricapillus, aiming to investigate the phylogenetic and phylogeography of O. atricapillus O. beecheyi. We analyzed two sets of mitochondrial cytochrome b gene (Cyt b) data: One 800 (bp) fragments of 118 individuals and a second one of 1140 (bp) for the 32 haplotypes found. Our own hypothesis is that specific characteristics used to distinguish O. artricapillus from O. beecheyi are at the same level than the differences among the recognized subspecies of O beecheyi. Under that condition, a genetic analysis will show that O. atricapillus are within the genetic variation of O. beecheyi, and the current diagnostic characters of O. atricapillus could be considered only at subspecific level. The analysis of molecular variance revealed that O. atricapillus is not significantly different from O. beecheyi, and that, apart from highland populations in the Sierra Nevada, the sampled populations of O. beecheyi and O. atricapillus are not significantly different among all of them.

Bats are plague controllers and effective pollinators for many plant species, and thus, an important link for the ecosystem balance. They have evolved a sophisticated system to analyse reflections from their own emitted sounds to perceive their environment; ability known as echolocation. These signals are therefore useful to classify and determine abundance and distribution of species. However, recording ultrasound is challenging since real time and frequency monitoring is not usually available. Moreover, ultrasound signals for echolocation are highly variable since they depend on environmental conditions, biotic factors, and the bat´s task. Acoustic identification of species from their echolocation signals relies on having a reliable database of signals to compare. This paper describes a portable chamber that provides controlled and reproducible conditions for bat echolocation recordings. Conventional field recordings and recordings using the chamber for verspertilionid bats (Lasiurus xanthinus and Parastrellus hesperus hesperus) and Phyllostomid bats (Leptonycteris yerbabuenae) are presented to highlight the advantages of using this chamber.

Seven taxa of rodents endemic to northwestern Mexico recently have been reported as extirpated: Peromyscus maniculatus cineritius, P. pembertoni, Dipodomys gravipes, Oryzomys couesi peninsularis, Neotoma anthonyi, N. bunkeri, and N. martinensis (Lawlor 1983, Mellink 1992, Smith et al. 1993, Alvarez-Castañeda 1994, Alvarez-Castañeda and CortésCalva 1996). Extirpation of these rodents may be a consequence of human activity and the introduction of nonnative species, primarily cats (Felis silvestris) that prey on the endemic rodents and Mus musculus and Rattus rattus that may compete with native species for resources (Alvarez-Castañeda 1997). We report the possible extirpation of an endemic rodent, Bailey’s pocket mouse (Chaetodipus baileyi fornicatus), from Isla Montserrat.

In ecology, bats have become a major subject of study. Some pollinate and disperse the seeds of many tropical plants; some help to control insect populations; a few affect livestock by sucking blood, but in all cases bats are indispensable links in ecosystems. Bats use of sound waves make echolocation calls monitoring a powerful tool for distribution, census, and present studies. This technique depends on having a reliable database of sounds for species identification purposes. Although there are several databases of echolocation sounds; the signal emitted by a bat depends on environmental conditions (vegetation, weather conditions), biotic factors (prey size, movement, defensive measures), and the specific task (seek, flee, pursue, evade, wandering, obstacle avoiding). This variability makes comparisons among databases difficult. A portable chamber made of common materials for in situ recording under controlled conditions is presented. The use of the chamber is proposed as a tool which might help to generate databases that could be reliable compared. Nine species of desert bats from the northwest region of Mexico were recorder using the chamber under controlled conditions and compared with field recordings. The performance of the chamber and the utility of the database generated for filed identification are presented.

Islands in the seas of northwestern Mexico have the largest number of insular endemic species in North America. The islands have the greatest number of extinct mammalian taxa in Mexico, and many of the remaining taxa are rare, threatened, or endangered. Thus the Mexican government’s plan to build 24 modern ports—the “Escalera Nautica” project—will place enormous pressure on island species, which are exceptionally vulnerable to human activities, including the introduction of alien species. The intensified port activities would most likely lead to an ecological disaster. Several mammal species inhabiting the islands are already close to the limit of their capacity to survive. For many endangered species, a small change in habitat can be the final push into extinction. In this article, we make some recommendations to try to prevent the extinction of species at risk.

"Los taxa de Haplomylomys (Rodentia: Cricetidae) son un subgénero de Peromyscus. Se distribuyen ampliamente en el suroeste de Estados Unidos de América y el noroeste de México, incluyendo varias islas circundantes a la península de Baja California (PBC). La taxonomía de Haplomylomys ha sido estudiada desde principios del siglo XX, cuando se propusieron las primeras clasificaciones con base en caracteres morfológicos. Sin embargo, las relaciones genealógicas entre las especies y subespecies de Haplomylomys aún no han sido completamente entendidas debido a la presencia de taxa crípticos. Los objetivos de este trabajo fueron evaluar la historia evolutiva del subgénero Haplomylomys y dilucidar los principales eventos geológicos y climáticos que han estructurado la filogenia del grupo. Se consideró que debido a que el proceso de aislamiento de los roedores de la PBC está asociado al Último Máximo Glacial (ÚMG), se espera que las formas insulares de Haplomylomys no difieran genéticamente con respecto a los taxa de tierra firme y que sean subespecies de éstas. Para evaluar este supuesto, se amplificaron y secuenciaron tres genes mitocondriales (Cytb [800 pares de bases (pb)], COI [658 pb] y COIII [700 pb]). El tamaño de muestra fue de 61 individuos, considerando tanto poblaciones de tierra firme como insulares, los cuales pertenecen a 11 taxa reconocidos actualmente como especies. Como grupo externo se incluyeron a las siguientes especies: Peromyscus maniculatus, P. sejugis, P. boylii y P. leucopus. Para determinar las distancias genéticas entre los taxa se emplearon los modelos de evolución molecular Kimura 2-parametros y Jukes-Cantor. Además se determinó el modelo evolutivo correspondiente para cada gen mitocondrial con la finalidad de realizar análisis filogenéticos individuales y un análisis particionado con todas las secuencias concatenadas (2,158 pb). Se obtuvieron dos modelos de evolución molecular; para Cytb se empleó el modelo GTR+I+G, y para COI y COIII el modelo TIM2+I+G. Todos los métodos de inferencia filogenética (Neighbor-Joining, Máxima Verosimilitud, Inferencia Bayesiana y estimación bayesiana de los tiempos de divergencia [datación molecular]) fueron consistentes en la identificación de cuatro clados monofiléticos recíprocos con un fuerte soporte de bootstrap (> 90%) dentro del grupo eremicus..." "The taxa of Haplomylomys (Rodentia: Cricetidae) are a subgenus of Peromyscus. It’s are widely distributed in northwestern Mexico and the southwestern United States, including several islands surrounding the Baja California peninsula (BCP). The taxonomy of Haplomylomys has been studied since the beginning of the 20th century, when the first classifications were proposed based on morphological characters. However, the genealogical relationships between islands taxa within the eremicus group remain poorly understood due to the presence of cryptic taxa. In this work, the goals were to assess the evolutionary history of Haplomylomys and identify the main geological and climatic events that might have affects its phylogeny. I tested the hypothesis that the island taxa of the subgenus Haplomylomys show limited genetic differences with respect to mainland taxa because its recent isolation process has been associated with the Last Glacial Maximum (LGM). Phylogenetic relationships were analyzed using three mitochondrial gene fragments (Cytb [800 base pairs (bp)], COI [658 bp], and COIII [700 bp]) from 61 individuals, considering both mainland and island populations belong to 11 taxa currently recognized as species, collected through the geographic range of Haplomylomys. As outgroup group the following species were included: Peromyscus maniculatus, P. sejugis, P. boylii, and P. leucopus. Genetic distances were calculated using the Jukes-Cantor and Kimura 2-parameter models of molecular evolution. To determine the best model of evolution of each gene mitochondrial and concatenated data set (2,158 bp), the Akaike information criterion was used. The parameters obtained from two evolutionary models for the phylogenetic approaches were used. For Cytb the model GTR+I+G was used, while for COI and COIII was the model TIM2+I+G. Phylogenetic inferences (Neighbor-Joining, Maximum likelihood, Bayesian inference, and molecular dating) identified two main clades. The first includes P. californicus; the second, all the species within the eremicus group divided into four clades with strong bootstrap support (> 90%). Phylogenetic analyzes, molecular dating, and the values obtained from measures of genetic distances suggest taxonomic changes at species and subspecies level in three clades identified for island taxa of the eremicus group..."