Nuevos registros de distribución del gorrión de Worthen Spizella wortheni en San Luis Potosí, México

"El rango de distribución restringido y el pequeño tamaño poblacional del gorrión de Worthen han ocasionado que esta ave sea considerada una especie amenazada en México y a nivel internacional. Aquí reportamos nuevos registros de esta ave los cuales expanden su rango de distribución conocido en los últimos cuarenta años y abren la posibilidad del uso de hábitats adicionales que no habían sido documentados anteriormente. Por lo tanto es importante realizar esfuerzos para documentar posible actividad reproductiva en estos hábitats.

Raptor functional diversity in scrubland-agricultural landscapes of northern-central-Mexican dryland environments

"Raptor birds have widespread distributions in different environments throughout the planet. Yet, they are highly sensitive to landscape disturbances. We studied raptors in northern-central Mexico at the Highland plateau of San Luis Potosí and Zacatecas, in three landscape types that differed in proportion of agriculture. Our main goal was to determine whether small proportion of agriculture at the landscape level influences species richness, ecological diversity, and functional diversity. We conducted raptor road surveys during 1 year, from April 2015 to February 2016. We registered a total of 332 birds belonging to 14 diurnal raptor species. The most abundant species were Cathartes aura (turkey vulture), Falco sparverius (American kestrel), Caracara cheriway (crested caracara), and Buteo jamaicensis (red-tailed hawk). Three species: Aquila chrysaetos (golden eagle), Pandion haliaetus (osprey), and Falco columbarius (merlin) were exclusively recorded in the less-degraded, scrubland landscapes. However, no significant differences on average diversity were found between landscape types. Contrastingly, scrubland landscapes had the highest average functional diversity, followed by mixed landscapes, and then by agricultural landscapes, with significant differences in functional diversity between scrubland and agricultural landscapes. Overall, observed species richness in the study area formed four functional groups. These groups change and loose species as proportion of agriculture in the landscape progressively increases. The results suggested that the contribution of species richness to functional diversity, both for scrubland landscapes, which have the greatest functional diversity, and agricultural landscapes, which hold the smallest functional diversity, is important because there is substantial functional redundancy among landscape types.

First records of the White Ibis (Eudocimus albus) from the highland plateau of San Luis Potosi, Mexico

"Reportamos dos observaciones visuales del ibis blanco (Eudocimus albus) de la Laguna de Los Coyotes, un afluente natural del manantial la Media Luna que se localiza en el municipio de Rioverde, San Luis Potosí, México. Los avistamientos ocurrieron en septiembre de 2011 y febrero de 2012. Este es el primer reporte de la presencia de esta ave en dicha localidad, y es importante porque la especie ha sido escasamente encontrada en ambientes no ribereños del Altiplano Mexicano.""We report two visual records of the White Ibis (Eudocimus albus) at "Los Coyotes" lagoon, a natural affluent of the water spring "Media Luna" located at the "Rioverde" municipality of San Luis Potosi, Mexico. These visual encounters took place on September 2011 and February 2012. This is the first published report of the species at this locality, and our finding is important because this species has been barely found in non-coastal wetlands of the Mexican highland plateau.

Richness and density of grassland bird species assessed by two methods

"Dentro de las aves, las de pastizal son de las más amenazadas en el mundo. En México, estos ecosistemas se han visto afectados por el sobre-apacentamiento con ganado doméstico y la conversión a la agricultura. Para desarrollar planes de conservación es necesario evaluar las poblaciones y utilizar herramientas precisas que permitan conocer el estado de éstas. El objetivo del estudio fue comparar el conteo de aves por transecto y el puntual, para contrastar su efectividad al estimar la riqueza de especies y densidad de poblaciones, mediante cuatro diferentes distancias de detección en tres tipos de hábitats: pastizal mediano abierto, sabana y áreas agrícolas, las cuales diferían en su cubierta vegetal. La cuantificación se realizó en el periodo invierno-primavera 2004 - 2005. Las densidades más altas se obtuvieron con la técnica del conteo puntual en los intervalos de 0 - 25 y 25 - 50 m. El mayor número de especies se detectó con ambos métodos en las distancias de 0 a 75 m. Los resultados son consistentes para las dos estaciones y los tres hábitats, por lo que es posible combinar los métodos probados cuando se realicen inventarios referentes a la diversidad de aves de los pastizales semiáridos de México.""Inside the birds group, the grassland birds are the most threatened in the world. In Mexico, these ecosystems have been affected by overgrazing by domestic livestock and conversion of soil to agriculture. To develop conservation plans is necessary to evaluate birds populations and the use of tools that help us to accurately assess the status of bird populations. The main objective of our study was to compare two bird-count methods (transect and point count), to contrast the effectiveness of estimating species richness and population densities at four detection distances in three contrasting grassland habitats: open middle grassland, savanna grassland and agriculture lands, these habitats differ in vegetation cover. Bird counts were conducted during winter 2004 and spring 2005. Estimated population densities were highest when using the PC method at distances of 0 - 25 m and 25 - 50 m. The greatest number of species was detected when both methods at distances of 0 to 75 m. These results were consistent for both seasons and for the three grassland habitats, in base to these results, combining both methods when realizing birds' diversity inventories in Mexican semiarid grasslands.

Nuevos registros de distribución del gorrión de Worthen Spizella wortheni en San Luis Potosí, México

El rango de distribución restringido y el pequeño tamaño poblacional del gorrión de Worthen han ocasionado que esta ave sea considerada una especie amenazada en México y a nivel internacional. Aquí reportamos nuevos registros de esta ave los cuales expanden su rango de distribución conocido en los últimos cuarenta años y abren la posibilidad del uso de hábitats adicionales que no habían sido documentados anteriormente. Por lo tanto es importante realizar esfuerzos para documentar posible actividad reproductiva en estos hábitats

ABERRACIONES CROMÁTICAS EN AVES DE MÉXICO: UNA REVISIÓN Y REGISTROS RECIENTES EN EL ESTADO DE SAN LUIS POTOSÍ

Resumen · La presencia de aberraciones cromáticas en las aves ha llamado la atención de los investigadores desde hace mucho tiempo. En México se ha notado un reciente incremento de artículos publicados referente a este tema. Por ello se planteó como objetivo de este estudio llevar a cabo una amplia revisión sobre la literatura publicada sobre el tema de aberraciones cromáticas en México. Adicionalmente reportamos casos recientes de aberraciones cromáticas para cuatro especies de aves Paloma de Collar Turca (Streptopelia decaocto), Rascador Viejita (Melozone fusca), Gorrión de Worthen (Spizella wortheni) y Gorrión Doméstico (Passer domesticus) observadas en el estado de San Luis Potosí, México, correspondientes a un período de 10 años (2007–2017). En base a la revisión de literatura y datos del presente estudio, reportamos que existen registros de aberraciones cromáticas para México en 31 especies pertenecientes a 22 familias, presentado la familia Icteridae el mayor número de casos en las especies Tordo Sargento (Agelaius phoeniceus), Zanate Mayor (Quiscalus mexicanus), Tordo Ojos Rojos (Molothrus aeneus) y Tordo Cabeza Café (Molothrus ater). Seguido de seis familias representadas por dos especies (Columbidae, Cuculidae, Rallidae, Scolopacidae, Tyrannidae, Emberizidae).Abstract · Color aberrations in Mexican birds: a review and new records from San Luis Potosi Color aberrations in birds have attracted the attention of researchers for a long time. Mexico has seen a recent increase in articles published on this subject. Here, we conducted a comprehensive review of the literature published on the topic of chromatic abnormalities in Mexico. Additionally, we report new records of chromatic aberrations in the plumage of four species Eurasian Collared-Dove (Streptopelia decaocto), Canyon Towhee (Melozone fusca), Worthen᾽s Sparrow (Spizella wortheni), and House Sparrow (Passer domesticus) based on 10 years (2007–2017) of observations in the state of San Luis Potosí, Mexico. Based on the literature review and on our data from this study, we show that there are reports of chromatic abnormalities for Mexico in 31 species belonging to 22 families. Family Icteridae presented the greatest number of cases for the following species: Red-Winged Blackbird (Agelaius phoeniceus), Great-Tailed Grackle (Quiscalus mexicanus), Bronzed Cowbird (Molothrus aeneus), and Brown-Headed Cowbird (Molothrus ater). For other six families, we recorded two species with chromatic aberration records (Columbidae, Cuculidae, Rallidae, Scolopacidae, Tyrannidae, Emberizidae)

Haemosporidian parasite prevalence, parasitemia, and diversity in three resident bird species at a shrubland dominated landscape of the Mexican highland plateau

"Background: Studies of avian haemosporidians allow understanding how these parasites affect wild bird populations, and if their presence is related to factors such as habitat loss, degradation and fragmentation, and climate change. Considering the importance of the highland Plateau of Mexico as part of the North American bird migratory route and as a region containing important habitat for numerous bird species, the purpose of this study was to document haemosporidian species richness and how habitat degradation, bird body condition, and distance from water sources correlate with bird parasitemia. Methods: We assessed the presence of avian haemosporidians in three resident bird species through microscopy and PCR amplification of a fragment of the haemosporidian cytochrome b gene. Average parasitemia was estimated in each species, and its relationship with habitat degradation through grazing, bird body condition and distance from water bodies was assessed. Results: High levels of parasitemia were recorded in two of the three bird species included in this study. Four lineages of haemosporidians were identified in the study area with nearly 50 % prevalence. Areas with highly degraded shrublands and villages showed higher parasitemia relative to areas with moderately degraded shrublands. No strong relationship between parasitemia and distance from water bodies was observed. There were no significant differences in prevalence and parasitemia between the two bird species infected with the parasites. Two of the sequences obtained from the fragments of the parasite's cytochrome b gene represent a lineage that had not been previously reported. Conclusions: Haemosporidian diversity in arid zones of the Mexican highland plateau is high. Shrubland habitat degradation associated to the establishment of small villages, as well as tree extraction and overgrazing in the surroundings of these villages, significantly enhances parasitemia of birds by haemosporidians.

BREEDING BIOLOGY OF THE LOGGERHEAD SHRIKE LANIUS LUDOVICIANUS IN CENTRAL MEXICO

The Loggerhead Shrike Lanius ludovicianus has an exceptionally broad distribution in North America, with the southernmost populations found in central Mexico. The species has experienced severe declines throughout its range, and thus, is of conservation concern, particularly in USA and Canada. Life history data is scarce for Mexico, where both resident and migratory populations are found. In this study we provide information on the breeding biology of a population of Loggerhead Shrikes near the southern limit of its distribution in central Mexico. Based on data from 70 nests over three breeding seasons (2007–2009), we estimated the average nest density as 0.85 nests/ha with most nests built in mesquite trees Prosopis laevigata. Average clutch initiation date was March 28, with variation among years. The breeding period averaged 3.5 months, starting at the end of February, and extending to early June. The laying period averaged 4.6 days, incubation averaged 18 days, and the average brooding period 16.6 days, for a total average of 39.2 days from egg laying to the end of brooding. Clutch size averaged 4.1 eggs (range 2–5) with a mode of four eggs. The nesting success for the three years combined was 64.3% (range 54.5–68.9%). Daily survival rate was estimated to be 0.749 using logistic exposure. The average number of fledglings at successful nests was 1.5. Predation was the main cause of nest failure, accounting for 35.7% of all active nests. In general, life history traits of this Mexican Loggerhead Shrike population are like those reported for breeding populations in more northern parts of its range; however, clutch size was smaller and average incubation period was significantly longer, probably because of latitudinally-related environmental factors

Luis mayor (Pitangus sulphuratus) en el Altiplano Mexicano

The Great kiskadee (Pitangus sulphuratus) has a continuous distribution in both slopes of Mexico, mainly in tropical zones. As a result of monthly samplings from December 2006 to August 2013, we report the occurrence of this species in eastern Aguascalientes and the Highland Plateau region of San Luis Potosi. Based on these records, we suggest that this species can be considered as a resident for this region, thus suggesting that its geographic distribution could be extended to the central plateau of Mexico

Potential distributional patterns of three wild ungulate species in a fragmented tropical region of northeastern Mexico

"In the northernmost American tropical forests of eastern Mexico, we analyzed the potential distribution of three ungulate species, Odocoileus virginianus, Mazama temama and Pecari tajacu, in response to several physical, climatic, biological, and anthropogenic variables, in order to identify environmental factors affecting distribution and potential key areas for ungulate conservation. Current presence records for these species were gathered, and potential distribution models were built using Maximum Entropy niche modeling (MaxEnt). Model suitability surfaces were used to calculate remaining potential habitat areas in the region, as well as the potential sympatric area and representation of these areas in Natural Protected Areas. Biological and anthropogenic variables were the best species distribution predictors. Landscape composition (the proportion of different land-use and land-cover classes: forest, agriculture, and pasture) within approximately 120 ha, was the most important variable for all models, influencing each species differently with respect to their tolerance of altered habitats. The remaining potential area of all three species is fragmented and has apparently been nearly lost in plains (<14% remaining). Distribution models allowed us to detect an important location in the western portion of our study area which may function as a large biological corridor in the Sierra Madre Oriental mastogeographic province, a region heavily transformed by land use change. In the context of habitat transformation, management promoting quality matrix at the landscape level promises to be a viable alternative for ungulate conservation in tropical regions of Mexico.