Site occupation and range expansion by the endangered, Mexican microendemic San Quintín Kangaroo Rat (Dipodomys gravipes).

The San Quintin Kangaroo Rat, a rodent species microendemic to the San Quintin-El Rosario region in Baja California that was considered potentially extinct in the wild, was recently rediscovered. This stimulated subsequent searches by us throughout its known distribution range and on sites that seemed suitable beyond its limits. We captured the species at 19 out of 42 localities surveyed, of which 6 are beyond its historically known distribution range, expanding the latter by ~60 km. Most sites occupied by the species occur on abandoned farmland in early ecological successional stages. Our data support that in the highly transformed agricultural landscape into which the region was converted in the 20th century, the species was able to survive undetected and colonize/recolonize sites once habitat became adequate after agricultural abandonment. This exhibits that the species is highly resilient and persisted as a metapopulation. Further research and conservation actions must be framed within context of the region's agricultural development.

Quintín­El Rosario, Baja California, considerada potencialmente extinta, se redescubrió recientemente. Ello estimuló búsquedas en todo su rango de distribución conocido y en sitios potenciales que parecían adecuados más allá de sus límites geográficos. Capturamos a la especie en 19 de 42 localidades, de las cuales 6 estaban fuera de su rango de distribución históricamente conocido, expandiendo este rango en ~60 km. La mayoría de los sitios ocupados por la especie se encuentran en tierras de cultivo abandonadas en etapas tempranas de sucesión ecológica. Nuestros datos respaldan la hipótesis de que el paisaje agrícola altamente antropizado, en el que se convirtió la región en el siglo XX, la especie sobrevivió en refugios y colonizó/recolonizó sitios una vez que el hábitat se volvió adecuado después de su abandono agrícola. Esto mostró que la especie es altamente resiliente y persistió como una metapoblación. Las futuras acciones de investigación y conservación deben enmarcarse en el contexto del desarrollo agrícola de la región.

Reconsideration of the nomadic condition of the southernmost Guachichiles based on the relationship with their environment.

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.

A semiarid fruit agroecosystem as a conservation-friendly option for small mammals in an anthropized landscape in Mexico.

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.

Biodiversity conservation in an anthropized landscape: Trees, not patch size drive, bird community composition in a low-input agro-ecosystem.

One of the most typical agro-ecosystems in the Llanos de Ojuelos, a semi-arid region of central Mexico, is that of fruit-production orchards of nopales (prickly pear cacti). This perennial habitat with complex vertical structure provides refuge and food for at least 112 species of birds throughout the year. Nopal orchards vary in their internal structure, size and shrub/tree composition, yet these factors have unknown effects on the animals that use them. To further understand the conservation potential of this agro-ecosystem, we evaluated the effects of patch-size and the presence of trees on bird community composition, as well as several habitat variables, through an information-theoretical modelling approach. Community composition was obtained through a year of census transects in 12 orchards. The presence of trees in the orchards was the major driver of bird communities followed by seasonality; bird communities are independent of patch size, except for small orchard patches that benefit black-chin sparrows, which are considered a sensitive species. At least 55 species of six trophic guilds (insectivores, granivores, carnivores, nectivores, omnivores, and frugivores) used the orchards. Orchards provide adequate habitat and food resources for several sensitive species of resident and migratory sparrows. The attributes that make orchards important for birds: trees, shrubs, herb seeds, and open patches can be managed to maintain native biodiversity in highly anthropized regions with an urgent need to find convergence between production and biological conservation.

Colony-level assessment of Brucella and Leptospira in the Guadalupe fur seal, Isla Guadalupe, Mexico.

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.

Waterbirds and human-related threats to their conservation in Laguna Cuyutlán, Colima, México.

Laguna Cuyutlán, the only large wetland in a span of 1,150 km along the Pacific coast of Mexico, has been neglected as to its importance for waterbird conservation. At least 25 waterbird species nest there, with some of their colonies being very relevant, and at least 61 waterbird species use the lagoon during their non-breeding season. This lagoon has been subject to several structural modifications, including levees and artificial channels which connect it to the sea, while water supply from continental sources has diminished, although its role has not been assessed yet. Salt extraction and artisanal fishery, the main economic activities, do not seem to pose a threat to waterbirds. Among potential threats to this acquatic ecosystem, are the raw sewage discharges that exist near urban areas, and pesticides from the surrounding agricultural lands might reach the lagoon. Seemingly, the most serious threat comes from waterway development in connection with a re-gasification plant to be built, and planned future port expansion, which could potentially increase water levels and alter important habitats for nesting and foraging. We recommend that: the area be declared an Important Bird Area; the development of the re-gasification plant and future port includes a levee to prevent alterations in water level in the remaining sections of the lagoon; supply of exogenous chemicals and waste products be prevented and monitored; alleged benefits from water interchange between the lagoon and the sea through artificial channels should be re-evaluated; and the role of fresh water supplies to the lagoon should be paid attention to.

Waterbirds and human-related threats to their conservation in Laguna Cuyutlán, Colima, México

Laguna Cuyutlán, the only large wetland in a span of 1 150 km along the Pacific coast of México, has been neglected as to its importance for waterbird conservation. At least 25 waterbird species nest there, with some of their colonies being very relevant, and at least 61 waterbird species use the lagoon during their nonbreeding season. This lagoon has been subject to several structural modifications, including levees and artificial channels which connect it to the sea, while water supply from continental sources has diminished, although its role has not been assessed yet. Salt extraction and artisanal fishery, the main economic activities, do not seem to pose a threat to waterbirds. Among potential threats to this acquatic ecosystem, are the raw sewage discharges that exist near urban areas, and pesticides from the surrounding agricultural lands might reach the lagoon. Seemingly, the most serious threat comes from waterway development in connection with a re-gasification plant to be built, and planned future port expansion, which could potentially increase water levels and alter important habitats for nesting and foraging. We recommend that: the area be declared an Important Bird Area; the development of the re-gasification plant and future port includes a levee to prevent alterations in water level in the remaining sections of the lagoon; supply of exogenous chemicals and waste products be prevented and monitored; alleged benefits from water interchange between the lagoon and the sea through artificial channels should be re-evaluated; and the role of fresh water supplies to the lagoon should be paid attention to. Rev. Biol. Trop. 57 (1-2): 1-12. Epub 2009 June 30.

Laguna Cuyutlán, el único humedal grande a lo largo de 1 150 km del Pacífico mexicano, no ha sido considerado un ecosistema natural importante para la conservación de aves acuáticas. Cuando menos 25 especies de aves acuáticas anidan ahí, y al menos 61 especies de aves acuáticas la usan fuera de la temporada reproductiva. Esta laguna ha sufrido varias modificaciones estructurales, y el aporte de agua dulce ha disminuido, sin que se conozcan sus consecuencias. La extracción de sal y la pesca artesanal, las principales actividades económicas, no parecen ser riesgo para las aves acuáticas. Entre los riesgos potenciales, están las aguas negras cerca de zonas urbanas y los plaguicidas de zonas agrícolas colindantes. Aparentemente, el riesgo más serio deriva del desarrollo marítimo asociado con una planta regasificadora a construirse pronto, y del desarrollo portuario futuro, que podrían incrementar los niveles de agua en la laguna y alterar los hábitats de las aves acuáticas. Recomendamos que: el área se declare como AICA; el desarrollo futuro incluya un dique para prevenir alteraciones en el nivel del agua en el resto de la laguna; el aporte de sustancias agroquímicas y aguas negras se monitoree; se reevalúen los supuestos beneficios del intercambio de agua entre la laguna y el mar por medio de canales artificiales; y se investigue científicamente los aportes de agua dulce a la laguna.

Organchlorine content and shell thickness in brown booby (Sula leucogaster) eggs in the Gulf of California and the southern Pacific coast of Mexico.

We determined egg concentrations of organochlorines and thickness of eggshells from brown boobies at eight colonies ranging from the northern Gulf of California to southern Mexico. The only common residue was that of DDE, which was found in almost all eggs. DDE content apparently reflected pre-1990 DDT use in nearby agricultural areas and, at one site, intensive mosquito control for high-end tourism development. There were no inter-colony differences in eggshell thickness, and variation in this variable likely reflected individual bird characteristics and/or individual feeding source. This variable was not a good proxy to DDE exposure of brown boobies, under current DDE levels in the brown booby trophic chain. In the northern Gulf of California, eggshell thickness has recovered to pre-DDT conditions. Our data indicate that the Gulf of California and southwestern coast of Mexico have a healthy near-shore marine environment, as far as organochlorines are concerned.

Waterbirds (other than Laridae) nesting in the middle section of Laguna Cuyutlán, Colima, México.

Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus), Tricolored Egret (Egretta tricolor), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Great Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Black-crowned Night-heron (Nycticorax nycticorax), Yellow-crowned Night-heron (Nyctanassa violacea), Green Heron (Butorides virescens), Roseate Spoonbill (Platalea ajaja), White Ibis (Eudocimus albus), Black-bellied Whistling-duck (Dendrocygna autumnalis), Clapper Rail (Rallus longirostris), Snowy Plover (Charadrius alexandrinus), and Black-necked Stilt (Himantopus mexicanus). These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla), Royal Terns (Thalasseus maximus), Gull-billed Terns (Gelochelidon nilotica), Forster's Terns (S. forsteri), Least Terns (Sternula antillarum), and Black Skimmer (Rynchops niger), and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status.

Waterbirds (other than Laridae) nesting in the middle section of Laguna Cuyutlán, Colima, México

Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus), Tricolored Egret (Egretta tricolor), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Great Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Black-crowned Night-heron (Nycticorax nycticorax), Yellow-crowned Night-heron (Nyctanassa violacea), Green Heron (Butorides virescens), Roseate Spoonbill (Platalea ajaja), White Ibis (Eudocimus albus), Black-bellied Whistling-duck (Dendrocygna autumnalis), Clapper Rail (Rallus longirostris), Snowy Plover (Charadrius alexandrinus), and Black-necked Stilt (Himantopus mexicanus). These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla), Royal Terns (Thalasseus maximus), Gull-billed Terns (Gelochelidon nilotica), Forster's Terns (S. forsteri), Least Terns (Sternula antillarum), and Black Skimmer (Rynchops niger), and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status.

Durante la prospección de la parte media de la Laguna Cuyutlán, una gran laguna costera en Colima, México, entre 2003 y 2006, documentamos la anidación de 15 especies de aves acuáticas que no pertenecer a la familia Laridae: Phalacrocorax brasilianus, Egretta tricolor, Egretta thula, Egretta caerulea, Ardea alba, Bubulcus ibis, Nycticorax nycticorax, Nyctanassa violacea, Butorides virescens, Platalea ajaja, Eudocimus albus, Dendrocygna autumnalis, Rallus longirostris, Charadrius alexandrinus e Himantopus mexicanus. Estas se suman a seis especies de Laridae que anidan en esta parte de la laguna: Larus atricilla, Thalasseus maximus, Gelochelidon nilotica, Sterna forsteri, Sternula antillarum y Rynchops niger, y a cuando menos 57 especies de aves acuáticas que la usan durante la época no reproductiva. Con estas comunidades ornitológicas, la Laguna Cuyutlán es un sitio importante para las aves acuáticas, que debería recibir estatus de protección.

Coastal waterbirds of El Chorro and Majahuas, Jalisco, México, during the non-breeding season, 1995-1996

We studied how waterbirds used two small estuaries during the non-breeding season of 1995-1996. These estuaries, El Chorro and Majahuas, were located in the middle of a large span of non-wetland habitat along the Pacific coast of México. Whereas El Chorro was basically a large and open waterbody, Majahuas was a long and narrow corridor flanked by mangroves. The two estuaries had 77 species throughout our study, but shared only 58, due to differences in their habitat. Seabirds comprised 66 of all the birds; grebes, ducks and rails 16; shorebirds 12 and herons and egrets 5. During late winter and early spring a very reduced number of migratory species accounted for the dominance of seabirds. Sterna hirundo and Phalacrocorax brasilianus accounted for 40 and 33, respectively, of all the seabirds. Opening or closure of the estuary mouth at El Chorro affected the bird communities at both sites, by exposing or inundating a large mudflat in that estuary. Overall, however, time of the year was more important in the composition of the bird assemblages. Both estuaries should be considered as a single unit.