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The San Quintín kangaroo rat ( Dipodomys gravipes Huey, 1925) is one of the three kangaroo rats in northwestern Baja California and the largest of them in most body dimensions. After a dramatic population decline in the 1980s, it was declared as potentially extinct in the wild by Mexican law. In 2017, the species was claimed to be rediscovered, but critical data supporting the species recognition were not provided. The question remained: Was the San Quintín kangaroo rat really rediscovered? We analyzed individuals identified by us as D. gravipes to validate our identification. We compared cranial morphometric and mitochondrial data of on-purpose collected specimens with those of historic specimens and with those of sympatric kangaroo rats in Baja California, particularly the Dulzura kangaroo rat ( Dipodomys simulans (Merriam, 1904)). Cranial morphometry and body dimensions of current specimens are indistinguishable from those of historic D. gravipes, while being different from D. simulans in most dimensions. External measurements such as cranial traits adequately distinguish both species. The mitochondrial analysis revealed strong support for the species grouping of sequences of our specimens and DNA sequences of D. gravipes from the GenBank repository. This study comprises a morphometric and molecular confirmation of the presence of the species after >25 years of failures to find it.

Before the 16th century, tunales, majestic forests of arborescent nopales (Opuntia spp.), were a signature of the southern part of the Mexican Plateau. They were crucial for nonagricultural humans and wildlife and created the cultural identity of the region. Notwithstanding this, they have been drastically reduced and disparaged into modern times. We aimed at reconstructing the history of the disappearance of these tunales and elaborate on the ecological and cultural impacts of such disappearance. The historicizing of such processes is critical to establish restoration objectives concordant with ecological timeframes, rather than by human memory. To fulfill our objective, we reviewed published formal and gray literature (i.e., publications with limited circulation, theses), and unpublished archival documents, complementing this information and interpreting it with our own >25-year research experience each in the region. Despite some differing opinions, most 15th-century tunales were natural. Agricultural development in the 17th–19th centuries affected mostly tunales in humid bottomlands. Those on hills and slopes apparently escaped this initial transformation. After the Mexican Revolution (1910–1921), the plowing of hills and slopes destroyed many remaining tunales. Some persisted into the 21th century, but their felling has continued. Our study exemplifies how natural iconic communities once widely distributed can vanish almost inadvertently. With the loss of the tunales, the region has lost a unique, iconic plant community which harbored several plant species endemic to Mexico. Arborescent nopales are hardy, but to avoid the complete disappearance of the tunales, their ecological and biocultural importance and significance must be revaluated, and strong lobbying efforts and management actions developed.

El pecarí de collar (Pecari tajacu) se encuentra desde el norte de Argentina hasta el sur de Estados Unidos. En México se distribuye ampliamente en diferentes hábitats, principalmente en zonas tropicales. En la porción sur del Altiplano Mexicano su distribución histórica es poco clara y se le ha llegado a considerar extirpado por la sobreexplotación de sus poblaciones y el desarrollo de agricultura. Reportamos el primer registro de pecarí de collar para los Llanos de Ojuelos, obtenido mediante una cámara trampa colocada en hábitat xeroribereño. Este hallazgo confirma los informes de campesinos sobre la presencia de pecarí en la región, unos 20 km al norte del registro aquí reportado. Dos registros recientes de la especie en los municipios de Pinos, Zacatecas y Corral de Palmas, San Luis Potosí, distan aproximadamente 60 km del nuestro, por lo que serían de manadas diferentes. El sitio de donde proviene el registro aquí presentado es el cauce de un arroyo con cobertura densa de árboles y arbustos, rodeado de pastizal y matorral xerófilo con abundantes nopales que proveen alimento y agua a los pecaríes. La presencia del pecarí y otros mamíferos grandes, como el puma y el venado, en Los Llanos de Ojuelos puede aprovecharse para realizar campañas de sensibilización entre los habitantes para conservar los recursos naturales de la región.

Para incrementar el conocimiento sobre las aves en los Llanos de Ojuelos, presentamos 12 registros de especies, obtenidos entre 2000 y 2019. Los Llanos de Ojuelos es una región semiárida y altamente antropizada con vacíos notorios de información sobre la biodiversidad. Nuestros registros incluyen ampliaciones a las áreas de distribución, rango altitudinal, hábitats utilizados y temporalidad consignados en la literatura. La mayoría de estas especies pueden considerarse visitantes ocasionales o accidentales, pero otras, quizá, sean residentes permanentes en la región. Uno de nuestros registros, el de Vireo atricapilla apunta a una reconsideración de la ruta migratoria propuesta. Las observaciones que aquí presentamos y analizamos ponen de manifiesto lo incompleto del conocimiento de la diversidad aviar en esta región y sobre la movilidad de las especies a escalas mayores que la regional. Más trabajos en la línea de esta contribución ayudarán a delinear mejores mapas de distribución e hipótesis de migración, especialmente bajo el escenario de cambio climático global.

In order to reassess the nomadic condition of the southern guachichiles, documentary, bibliographic and cartographic sources were analyzed and field work was carried out in order to define the geographical extension of the area of Tunal Grande. This proved that the tuna groves were far from being places of "misery, pain, suffering, fatigue, poverty, torment", as reported to Sahagun, and that the guachichiles of the Tunal Grande were not nomads. Besides, the location of the tuna groves helps to better understand the occupation and settlement forms of this region, as well as to understand the magnitude of the environmental changes in this region. Additionally, it is shown that Tunal Grande and Tunal Frontero provided an abundance of plant and animal resources to the ethnic groups that inhabited them and that the protection of the arborescent prickly pear of Charcas Viejas is of historical and biological interest.

Native grasslands worldwide have been degraded by grazing, but the processes involved have been studied insufficiently. Grasslands were a major habitat on the southern section of the Mexican Plateau when the Spaniards arrived 500 years ago. Since then, they have been impacted heavily through grazing, but the details and history of such impacts have not been established. We aimed at untangling almost 500 years of grazing of these grasslands, based on extensive searches of published information and of documents in historical archives. We identified three periods of ranching: Cattle, from the mid-16th to the mid-17th Centuries; sheep, reflecting a change from tall to short grasses; and, finally, goats and horses, along with sheep, asses and some cattle, after serious grassland degradation by the mid-20th Century. Overgrazing has impacted grassland composition in the region and its capacity to support livestock, but also, strongly affect some 20 species of native vertebrates and an unknown number of plant and invertebrate species. The current condition of some ranges and a livestock exclosure indicate that grassland improvement is possible, but realistic objectives based on biodiversity conservation and livestock production should be targeted, rather than utopic pre-livestock frameworks. Grasslands in the region at the time of Spanish arrival possibly had a mixture of grasses and herbs, but buffalo grass and the central Mexico tobosa grass are potential initial range management targets for grassland recovery of the ranges in worst condition, while blue gramma and the Mexican plateau gramma are good targets for ranges that still have some grass cover.

Mexican inland wetlands in the arid and semiarid interior highlands historically held very large numbers of waterbirds. However, they have been deteriorated by agriculture, industrial and urban development, tourism and aquaculture, although the effects of this are known poorly. At the southern end of the Central Plateau of Mexico, the region of El Llano, in the states of Aguascalientes and Jalisco, is densely dotted with wetlands amidst an agricultural landscape. The wetlands that existed at the time of Spanish contact have disappeared or been modified, but many new ones have been created, including large and mid-size reservoirs, as well as small cattle watering tanks. The importance of this region for waterbirds was analyzed based on the data from the USFWS mid-winter Mexican waterfowl surveys, and surveys by ourselves in 1984–1985 and from 2010 to 2014. The data exhibited a peak in diving ducks in the late 1970s, which might reflect reservoir restoration and, or creation. Wetland water levels as well as their use by waterbirds was highly variable during the study period, and some sites that were important in 1984–1985 have silted and dried up. The major waterbird trend in the survey area has been a steady increase in the number of the threatened Mexican Duck since the late 1970s until 2010–2011, that might have been resulted from a reduction in its hunting and egg collecting, and, or improvement in nesting habitat, along with reservoir creation or restoration.

The Mourning Dove (Zenaida macroura) is the most important game bird in central and northern Mexico, especially in the state of Jalisco. However, nothing is known about the dynamics of their populations during the nonbreeding season. To obtain an insight into these dynamics in Jalisco, Mourning Doves were counted every winter season from 2004/2005 to 2016/2017 along 10 routes throughout the state. Of these routes, only the data from eight were analyzed, because the two on the Pacific Coast were practically devoid of Mourning Doves. The data indicate Mourning Dove abundance in Jalisco during the nonbreeding winter season: (1) might reflect U.S. population changes two summers earlier, and (2) be significantly reduced from the 2004/2005 to 2014/2015 winter seasons, in part due to decreases in the U.S. central population, but seemingly also due to local, regional, or extra-regional processes yet to be understood.

The Red-billed Tropicbird (Phaethon aetehreus) is a seabird that breeds on islands in tropical seas. The Mexican government has listed it as threatened; however, the International Union for Conservation of Nature considers it of least concern, although it recognizes that its global population is decreasing. Its breeding ecology was studied at Pena Blanca island, Colima, Mexico, through monthly visits from 15 January 2008 to 10 December 2009. By extrapolating density in a 4,227-m2 survey area, 1,390 (2008) and 1,225 (2009) nests were estimated for the entire colony. In both years, the earliest eggs were laid in September, and the last active nests were recorded during 14 May–19 June, with peak activity on 7 March 2008 and 25 February 2009. Egg volume was not different between years (57.4 cm3 ± 5.1 vs. 56.8 ± 3.3), but nest success was higher in 2008 (77% vs. 57% in 2009). Highest nest densities occurred between January and May, coincident with regional upwelling processes (colder water and high concentration of nitrites, nitrates and chlorophyll-a). The Red-billed Tropicbird colony on Pena Blanca is the largest Mexican colony and one of the two largest colonies of the world.

Background The Guachichiles were a group of Chichimeca people that inhabited the southern and central parts of the Mexican Plateau. In the southern area of their distribution, they occupied and used the tunales, extensive forests of arborescent nopales (Opuntia spp.). Their pre-Columbian distribution was dissected by the Royal Silver Road established by the Spaniards, and this lead to them being main protagonists in the so-called Chichimeca War, during the sixteenth century. With very little first-hand documentation, the Guachichiles were described as savage, warring, primitive, hunting nomads, but little efforts have been done to understand their daily life habits. Based on the relationship of pre-Columbian southern Guachichiles with their environment, we re-valuate whether they were nomads, as the Chichimecas collectively have been labeled, or whether those living in tunales could live year-round in this habitat. As part of our analysis, we propose the primary plant and animal species that integrated their diet. Methods We draw information from a review of bibliographic sources, complemented with extensive searches in all pertinent Mexican archives. We carried out field work to define the geographical extent of the pre-Columbian territory of the southernmost Guachichiles, based on the Spanish Chronicles, remnant fragments of vegetation, landscape characteristics, and geographic names related with nopales. Using approaches from wildlife ecology, historical sciences and ethnobiological information on wild resources currently or recently used in the area, we proposed which resources were available to the southernmost Guachichiles, and how their primary diet might have been. Results The habitat of the southern Guachichiles, the tunal forest, was exuberant and rich in resources, having provided numerous plant products, of which tunas (prickly pears) and mesquite pods were of uttermost importance. At least 10 plant foods were available within the tunales. They would have consumed at least seven birds (including their eggs), six mammals, four reptiles, grubs, and honey, in addition to at least six vertebrate species hunted at the edges of the tunal with grasslands and shrublands or in more open patches of tunal. In addition to food, they prepared at least three alcoholic beverages, had access to two species of probable psychoactive beehive cacti and to one hallucinogenic mushroom species, and might have traded peyote from the north with outside-tunal Guachichiles. Conclusions The rich habitat in which southern Guachichiles lived allowed them to be largely sedentary, but this required that they prevented other groups from gathering and hunting in their habitat. As a result of them living in and defending the tunales, the Guachichiles could have been divided into two or three habitat-driven groups: Tunal Guachichiles, and grassland and, or shrubland Guachichiles.

Many studies have addressed the potential of low-input agroecosystems for biological conservation. However, most have been carried out on annual agroecosystems in temperate, developed countries. As agricultural surface will increase and natural protected areas alone will not warrant the conservation of biodiversity, it is crucial to include different types of agroecosystems in research and conservation efforts. In Mexico, perennial, low-input, fruit-oriented nopal orchards (Opuntia spp.), one of the few crops suitable for semiarid areas, are the 10th out of 61 most important fruit crops grown in the country. We assessed their value for conservation in an anthropized landscape by comparing their rodent assemblages with those in adjacent habitats and determined the influence of the latter on the rodent communities inside them. We live-trapped rodents in 12 orchards and adjacent natural xeric shrubland, grassland, and cropland. We captured 19 different species, of which 17 used the orchards. Four are Mexican endemics. Orchards have higher α diversity, species richness, and abundance than cropland and grassland and are not different from shrubland. The dominant rodent species are the same in orchards and shrubland, and where these two meet they integrate into one habitat. Within-habitat quality is a critical driver of the composition and diversity of rodent communities in the orchards studied, and the neighboring habitats do not modify them substantially. Increasing within-patch heterogeneity beyond a certain level is at the expense of habitat integrity and produces small-scale fragmentation reducing habitat quality. At a landscape scale, orchards contribute importantly to regional rodent diversity compared with other land use types, and appear to increase habitat connectivity between patches of shrubland. Orchards' higher α diversity would give them higher ecological resilience and make them better suited than grassland and cropland to contribute to the conservation of local biota. Nopal orchards should be considered conservation allies and incorporated in regional conservation plans. Regrettably, their future is unwarranted as producers face low revenues and lack of governmental support. Our confirmation that orchards have an important, positive impact on biodiversity can be used as a strong argument to lobby for incentives to safeguard this environmental friendly, low-input agroecosystem.

The importance of Laguna de Bustillos, Chihuahua, Mexico for waterbirds was evaluated during the 2011–2012 nonbreeding season. Thirty-seven percent of all birds were light geese (Chen caerulescens and C. rossii) and 44% consisted of three other species (Anas clypeata, Grus Canadensis, and Anser albifrons). Our data contrast with the historical counts of birds by the U.S. Fish and Wildlife Service using aerial surveys and may reflect recent land-use changes. Given the fact we observed some species in numbers that were far greater than previously recorded, our results provide evidence of the increasing importance of Laguna de Bustillos for wintering waterfowl.

Resumen ∙ El Bobo Café (Sula leucogaster) es un ave marina que anida en islas de mares tropicales y subtropicales. En el Pacífico mexicano ha sido objeto de varios estudios, pero, aún se conoce muy poco de la dinámica poblacional de sus colonias y la influencia de variables oceánicas sobre ellas. Estudiamos la ecología reproductiva del Bobo Café en tres islas del Pacífico mexicano: Pajarera y Cocinas, en Bahía Chamela, Jalisco y Peña Blanca, en Colima. Realizamos visitas mensuales a cada isla de enero de 2008 a diciembre de 2009. En 2008 hubo más nidos que en 2009, el número máximo estimado de parejas reproductoras en cada año (2008 y 2009 respectivamente) fue de 724 y 758 en Cocinas, 895 y 1,071 en Pajarera y 15,215 y 15,801 en Peña Blanca. Observamos nidos activos durante todo el año, pero la mayor densidad en ambos años ocurrió de abril a julio, coincidiendo con valores más altos de la temperatura superficial del mar y más bajos de concentración de clorofila a. El periodo reproductivo estuvo asociado con la presencia de masas de agua cálida, lo que es opuesto al patrón observado en colonias del Golfo de California, pero coincide con la presencia de peces migratorios. Así, los ajustes en la fenología reproductiva parecen asociados con condiciones locales favorables para la crianza de pollos (disponibilidad local de ciertas presas) durante el periodo cálido. Los parámetros reproductivos considerados indican que Peña Blanca, la colonia más grande, tiene las mejores condiciones para la reproducción (tamaño de puesta mayor, huevos más grandes y mejor éxito de eclosión). Las diferencias entre años y colonias parecen relacionadas con la variabilidad oceánica, la cual afecta a escala local la disponibilidad de presas. Con base en el número de individuos, que la hacen una de las colonias más grandes de la costa Pacífico mexicana, Peña Blanca califica para ser designada como un Área Importante para la Conservación de las Aves (AICA). Abstract ∙ Breeding ecology of the Brown Booby (Sula leucogaster) in three islands of the Mexican tropical Pacific Ocean The Brown Booby (Sula leucogaster) is a seabird that breeds in islands of tropical and subtropical seas. In the Mexican Pacific, it has been the subject of several studies, but little was known on the dynamics of its colonies and the influence of oceanic variables on them. We studied the breeding ecology of the Brown Booby at three southern Mexico islands: Pajarera and Cocinas in Bahía Chamela, Jalisco, and Peña Blanca in Colima. We visited each island monthly from January 2008 to December 2009. There were more nests in 2008 than in 2009, estimated maximum annual colony size (2008 and 2009, respectively) was 724 and 758 breeding pairs at Cocinas, 895 and 1,071 at Pajarera, and 15,215 and 15,801 at Peña Blanca. We observed active nesting year‐round, but the highest densities in both years were from April to July, when sea surface temperature was higher and levels of chlorophyll a, lower. The breeding period was associated with the presence of warm water masses, which is the opposite to the pattern previously recorded in Gulf of California colonies, but coincided with the presence of migratory fish. This difference in breeding phenology seems an adaptation to match local conditions (prey availability) during chick rearing. Breeding parameters (higher clutch size, egg volume, hatching success) point out that Peña Blanca, the largest colony, was superior to the other colonies in terms of breeding. Differences among years and colonies seem related to oceanic variability, which affects the local availability of prey. Based on the size of the colony, which makes it one of the largest colonies along the Mexican Pacific coast, the Peña Blanca colony qualifies to be nominated as Important Bird Area (IBA).

The California vole, Microtus californicus, from the high-altitude meadows of the Sierra San Pedro Martir, Baja California, Mexico had not been documented in 90 y and was thought to be extinct from this locality. In July of 2015, we documented an active, but reduced, population at one of its early collection sites. This population appears to be extremely restricted and should be protected and monitored.

El cambio antropico de uso de suelo es una de las principales amenazas para la conservacion de mamiferos carnivoros. Su impacto es heterogeneo geografica y biologicamente, por lo que es critico generar informacion local para valorar su estado y oportunidades de conservacion. Aqui actualizamos y sintetizamos la informacion sobre las 14 especies potenciales de carnivoros en los Llanos de Ojuelos, region que no obstante su fuerte antropizacion, retiene la mayor parte o toda la riqueza de varios grupos de vertebrados, aunque se desconocia el estado de los carnivoros. Analizamos registros nuestros de camaras automaticas, observaciones directas y rastros, la literatura disponible y registros en bases de datos digitales. Si bien las especies consignadas tienen distribucion amplia en Mexico, nuestro analisis evidencia cuan poca informacion existe sobre su presencia actual y puntual en los Llanos. La riqueza documentada y la presencia de individuos juveniles indican que la region aun conserva atributos biologicos que proveen recursos y condiciones para la mayoria de las especies originales de carnivoros. Nuestro trabajo muestra que algunos paisajes semiaridos agropecuarios pueden mantener una porcion considerable de las especies originales de carnivoros, y que con acciones de manejo oportunas podrian cimentarse como un eslabon de conservacion en contextos antropizados.

The Brown Booby Sula leucogaster is a seabird with a pantropical distribution across a wide variety of oceanic environments. Sexual size dimorphism in Brown Boobies has been proposed as an explanation for intersexual differences in foraging, but results have been inconsistent. We investigated whether there is context-dependent foraging behaviour driven by local environmental conditions. In this study, we evaluated (1) inter-sex differences in foraging behaviour (by capillary tubes, temperature and depth recorders, and diet) at two colonies in the Gulf of California: Isla San Jorge (ISJ) and Farallon de San Ignacio (FSI) and, (2) intercolonial and interannual differences in foraging behaviour, and (at ISJ) their relationship with local-scale environmental variation, using 5-day composite images of sea surface temperature (SST) and primary productivity (PP) as proxies. Inter-sex differences were few and inconsistent between years, and smaller than overall differences between years and localities. At ISJ, Br...

Breeding of Wood Storks (Mycteria americana) in western Mexico is limited to a few known sites from Guerrero to Chiapas. However, except for nesting at one Oaxaca site in 2005, all the colonies were reported over 35 years ago, while more recently published bird surveys in coastal wetlands of western Mexico have not reported any nesting Wood Storks. During April 2014, a newly established colony at Mogote Prieto, a mangrove-fringed island in Laguna Cuyutlan's Basin III, Colima, was documented. This colony was visited on seven occasions during the spring and summer of 2014 and 2015. Maximum numbers in 2014 were 300 adult Wood Storks, including 36 clearly on nests and four carrying nesting materials (15 April 2014); 17 large, feathered chicks (12 June 2014); and 15 fledglings (12 July 2014). During 2015, there were fewer adults and nests, but more fledglings (n = 25 on 20 July 2015). Although the source of the nesting adults cannot be established, attention should be given to the conservation of thi...

The Californian Floristic Province, ranging from Northern California, USA, to the northwestern portion of the state of Baja California, Mexico, is a region of great biological richness that has a high risk of loss of species due to the effect of human activities. The main stressor that threatens its biodiversity is the change in land use and vegetation cover, which severely impacts the environmental and socio-economic systems’ functioning, affecting the provision of environmental services including the maintenance of biodiversity. The Tijuana River Watershed (TRW) is located within this floristic province. It has experienced rapid population growth during the last 50 years, demanding development of infrastructure in areas where native vegetation existed. As a binational watershed, it is an ideal area to study the processes involved in fragmentation and connectivity of natural environments, since both countries, while sharing the same environment, contrast greatly in their economic and social systems, which impose different pressures to these shared natural resources. Our research addresses change in vegetation cover and land use in the TRW, analyzing the changes and differences between Mexico and the United States. This analysis will be a basis to propose future management strategies for the conservation of ecological processes and biodiversity, according to the policies and actions for land management and conservation in both countries.

Diving abilities of fledging Brown Boobies (Sula leucogaster) were characterized during the transition to independence period, and potential inter-sex differences (females are larger than males) were evaluated. Mean and maximum diving depths and mean dive duration increased gradually following the fledglings' first flights. The diving rate and the proportion of active dives (U type) increased notably between days 21 and 25 after first flight. However, maximum dive duration was not influenced by time since first flight, and none of the dive variables evaluated was influenced by sex. In Brown Boobies, acquisition of diving abilities by juveniles is a gradual process, and this can be an important driver of their extended post-fledging parental care.

The relatively small population size and restricted distribution of the Guadalupe fur seal Arctocephalus townsendi could make it highly vulnerable to infectious diseases. We performed a colony-level assessment in this species of the prevalence and presence of Brucella spp. and Leptospira spp., pathogenic bacteria that have been reported in several pinniped species worldwide. Forty-six serum samples were collected in 2014 from pups at Isla Guadalupe, the only place where the species effectively reproduces. Samples were tested for Brucella using 3 consecutive serological tests, and for Leptospira using the microscopic agglutination test. For each bacterium, a Bayesian approach was used to estimate prevalence to exposure, and an epidemiological model was used to test the null hypothesis that the bacterium was present in the colony. No serum sample tested positive for Brucella, and the statistical analyses concluded that the colony was bacterium-free with a 96.3% confidence level. However, a Brucella surveillance program would be highly recommendable. Twelve samples were positive (titers 1:50) to 1 or more serovars of Leptospira. The prevalence was calculated at 27.1% (95% credible interval: 15.6-40.3%), and the posterior analyses indicated that the colony was not Leptospira-free with a 100% confidence level. Serovars Icterohaemorrhagiae, Canicola, and Bratislava were detected, but only further research can unveil whether they affect the fur seal population.

Laguna Cuyutlán (Colima, Mexico), an Important Bird Area, used to provide breeding habitat for ground-nesting waterbirds. During 2014 and 2015, nesting efforts of laughing gull, black skimmer, and royal, gull-billed and Forster's terns failed almost completely due to inundation, while least terns and snowy plovers fared the same during 2014. No anomalies in rainfall, tidal level, or coseismic subsidence explained such failure. Rather, the inundations were due to the enlarging of Canal Tepalcates that connects the lagoon with the sea, which was widened from 100 to 300 m and dredged to 17-m deep. Before this, the hydrodynamics were regulated by evaporation and runoff. Now, increased seawater volumes dominate the basin's hydrodynamics. The failure of Laguna Cuyutlán as a breeding habitat for these birds is an important threat for these species, as this lagoon held one of the < 20 colonies known for several of these species along the western coast of North and Central America. Documenting this demise of Laguna Cuyutlán for ground-nesting waterbirds transcends the regional scale as it emphasizes the little consideration still given to biodiversity vs. economic development, and is a warning for coastal projects in other developing areas of the world.

Loss and fragmentation of natural and semi-natural vegetation caused by agricultural intensification are related to many declines in shrubland bird populations, but they have received little conservation attention and research effort. In the Llanos de Ojuelos, a semiarid agricultural landscape in Mexico, patches of natural shrubland and nopal (or prickly pear) Opuntia spp. orchards harbour 60% of the regional avifauna, but prior to this study their value as nesting habitat for birds has not been assessed. In 2014 we recorded 143 nests of 25 species, 45% of which were of Mourning Doves Zenaida macroura. The nesting birds recorded account for 38% of all species known to use these habitats in this region and the number of nesting species is larger than in other North American semiarid and arid shrublands. Shrublands and orchards were not different in any habitat attributes measured, nor in the densities of nests found in them, but there were significantly more species nesting in shrublands. Nest height and visibility were not different between habitats, except for Mourning Doves, which nested at a lower height in orchards. Neither attribute affected nest success, except for in Black-chinned Sparrow Spizella atrogularis for whom successful nests were less visible. The assemblages of nesting birds might be explained better by particular plants used as nest substrate than by habitat attributes. Catclaws Mimosa aculeaticarpa var. biuncifera, Huisaches Vachellia farnesiana and V. schaffneri and nopal plants supported 56% of all nests, the latter being particularly important for Mourning Doves, while scarce Central-Mexico Yucca Yucca decipiens trees supported 40% of nesting species. There were interspecific differences in the phenology of nesting, which matched the feeding requirements of the young. Nopal orchards seem to provide abundant complementary food for birds that nest in shrubland patches. Nopal orchards and shrubland patches dotting the landscape may make the dominant agricultural matrix of the southern part of the Central Plateau of Mexico less detrimental to shrubland birds. Our study supports the idea that small patches of secondary shrubland can aid in biodiversity conservation in anthropized landscapes, a role that in this region is provided by shrubland remnant patches as well as nopal orchards.

We clarify misleading published information on the distribution of the endangered California vole (Microtus californicus) in Baja California, Mexico. We photo-document recent records for 2 of the 4 subspecies reported from Mexico and provide a map that includes several locations not previously published.

We aimed to elucidate the factors that influence the frequency of adoption and infanticide in the Blue-footed Booby (Sula nebouxii), a seabird with biparental chick care and high chick-rearing costs. We obtained data from two colonies during four breeding seasons. In addition, we removed parents from their nests for short periods of time (10 min) and fitted their chicks with polyethylene foam protectors, in order to record chick behavior, particularly interactions with neighboring adults. Adoption and infanticide occurred mostly in zones of high nest density and during years of high breeding success. The chicks adopted were 20–40 days of age, the age at which they acquire mobility and parents still experience a certain inability to recognize them. Adopted chicks were slightly younger than chicks in the broods into which they were adopted. In most cases, adoptees were younger than their siblings in their natal broods. We also recorded short-term (lasting only a few hours) alloparental care for chicks older than 40 days. When we excluded parents from nests and their chicks were attacked, it was female neighbors that physically attacked them, whereas males were more prone to brood or preen them; therefore, the sex with certainty of parenthood was more prone to practice infanticide, presumably to avoid adoption. The lack of aggressiveness by males might be due to the possibility of paternity, given the occurrence of extra-pair copulations in this species.

Bahia de Chetumal, on the Caribbean coast of the Yucatan Peninsula, is a large mesohaline bay that receives significant runoff of fresh water and supports salt-tolerant macrophytes and seagrasses. This bay is important for the endangered Antillean manatees (Trichechus manatus) in Mexico, and the maintenance of submerged populations of macrophytes is a priority in the conservation plans for manatees because these plants play an important role in the habitat of the manatee. We surveyed the cover and biomass of aquatic macrophytes in the northern section of Bahia de Chetumal from November 1998–April 2000 and found them restricted to a small proportion of the area with Halodule wrightii and Ruppia maritima being the most frequent species. Less common species were Najas marina, Thalassia testudinum, and the algae Batophora oerstedii and Chara chara. Cover (

The Colorado River Delta is one of the most impacted wetland systems in the world and has experienced massive habitat loss owing to severe restrictions in freshwater inflow as a result of dam construction and diversion of water for irrigation. However, the delta still offers nesting and foraging habitats for waterbirds, although the habitats available are highly fragmented and limited. Stable isotope ratio (SIR) analysis was used to assess quantitatively isotopic niche width of gull-billed terns (Gelochelidon nilotica), laughing gulls (Leucophaeus atricilla) and snowy egrets (Egreta thula) that nest at an inland and coastal location. The variance in carbon and nitrogen SIR of egg albumen indicated that inland colonies have a much broader isotope niche width (range 2.9 to 23.9) than coastal colonies (

Aim The Llanos de Ojuelos in Mexico's Central High Plateau supports unique Opuntia scrublands and the southernmost Chihuahuan grasslands. Although human activities have modified strongly its landscape and impacted its biodiversity at an unknown scale, such impacts are poorly known. We aimed at understanding how nocturnal rodent species distributed across the landscape and formed assemblages and on the role and integration of the different habitats at the landscape level. Location The study was carried out at 43 sites in a study area of approximately 3350 km2 in the Llanos de Ojuelos Methods During the Spring of 2008, we surveyed nocturnal rodents, through live-trapping. We redefined habitat classes based on log-linear multinomial regressions of rodent captures. Species rarefaction curves and true alpha, beta and gamma diversities were calculated for the different habitat classes. A map of the different habitats was constructed based on Landsat imagery. Results We captured 458 individuals of 20 rodent species. Multinomial regressions caused the merger of 11 a priori defined habitat classes into 7. Leguminous scrub and mixed nopaleras, both secondary habitats, had the highest alpha and gamma diversity values. Closed arboreal nopaleras and grasslands had the highest within-habitat variability (1Db) and the lowest area coverage. Within habitat 1Db was larger than landscape 1Db, because of the great overlap in rodent assemblage composition between the habitats. Main conclusions There are no 'typical' rodent assemblages per habitat class, but they are organized loosely and have fuzzy borders. Rodent community organization was highly species-centred. At the landscape level, secondary habitats have a profound effect on rodent diversity and should be included in management schemes for biological conservation. The most endangered habitats seem to be the closed arboreal nopaleras and grasslands. Any conservation efforts must consider their conservation and an increase in the size of remaining patches.

Castillo-Guerrero J.A., Guevara-Medina M.A. & Mellink E. 2011. Breeding ecology of the Red-billed Tropicbird Phaethon aethereus under contrasting environmental conditions in the Gulf of California. Ardea 99: 61–71.

Labor division in parental care and reduction of inter-sex competition by division of the foraging niche have been suggested as part of the evolutionary basis for reversed sexual size dimorphism in boobies (Sulidae). To test the potential viability of both hypotheses for the maintenance of dimorphism, we studied parental care and foraging behavior of the Blue-footed Booby (Sula nebouxii) in two colonies in the Gulf of California, Mexico. Proportion of time spent at the nest, feeding frequency, and time devoted to nest defense were used as indicators of parental care. Foraging ecology was evaluated through the number and duration of foraging trips, proportion of time dedicated to flight and to active feeding, rate and depth of diving, and diet. We found some inter-sex differences in foraging only under high demand conditions, such as food shortage or large broods. Inconsistent inter-sex differences seem to be part of a strategy to maximize chick rearing under a variable environmental regime.

From April to July 2008, we surveyed for breeding plovers at 32 sites in the semiarid highlands of Jalisco, Aguascalientes, Zacatecas, and San Luis Potosi, in the Central Mexican High Plateau. We documented evidence or presumption of breeding Snowy Plovers (Charadrius alexandrinus) at 3 sites, Killdeer (C. vociferus) at 15 sites, and Mountain Plovers (C. montanus) at 1 site Our surveys showed that the region is important breeding ground for only the Killdeer. We documented an apparent breeding range extension of the Mountain Plover to slightly more than 200 km south of its previously known breeding range.