ResumenLas anormalidades pigmentarias en aves han adquirido mayor importancia e interés entre la comunidad ornitológica; sin embargo, resulta necesario contar con una herramienta de diagnóstico apropiada que brinde los criterios para lograr un sistema de identificación entre los distintos tipos de anormalidades. Para ello, proponemos una clave dicotómica para su identificación en campo con base en terminología obtenida de literatura especializada y una asociación de caracteres fenotípicos de aves. También, reportamos la presencia de anormalidades pigmentarias en la coloración corporal y de plumaje de cinco especies de aves que han sido observadas de forma ocasional en áreas perturbadas por impacto antropogénico en Tamaulipas, México: melanismo en la tortolita mexicana (Columbina inca), aberración ino en la paloma turca (Streptopelia decaocto), aberración ino en el correcaminos norteño (Geococcyx californianus), leucismo parcial en el pijuy (Crotophaga sulcirostris) y leucismo parcial en el tordo de ojo rojo (Molothrus aeneus). Las evidencias de casos actuales sugieren un aparente aumento de especies en vida libre con variación en la pigmentación. Las causas que lo provocan aún son discutibles, por lo cual, relacionar qué factores naturales o artificiales están involucrados en estos padecimientos podrá contribuir a determinar su origen y detectar problemas a nivel de poblaciones. La clave dicotómica propuesta en la identificación de anormalidades pigmentarias puede ser una herramienta continua en contextos modernos, si se unifica la terminología empleada.Palabras clave: Aberraciones cromáticas, coloración atípica, melanina, carotenos, leucismo, albinismo. AbstractColor abnormalities in birds have been receiving increasing attention within the ornithological community. However, it is important to create an appropriate tool to provide criteria to allow the accurate identification of the different types of abnormalities. Towards this end we have developed a dichotomous key for field identification of common abnormalities based on the termino logy on the scientific literature and visible phenotypic characteristics of the birds. In addition, we report on color abnormalities in the body and plumage of five species of birds observed in anthropogenically disturbed areas in Tamaulipas, Mexico: melanism in the Inca Dove (Columbina inca), ino in the Eurasian Collared Dove (Streptopelia decaocto), ino in the Greater Roadrunner (Geococcyx californianus), leucism in the Groove-billed Ani (Crotophaga sulcirostris), and partial leucism in the Bronzed Cowbird (Molothrus aeneus). Evidence of current cases suggest a significant increase in free-living species with variation in pigmentation. The causes that trigger it are still disputable, therefore, to relate which natural or man-made factors are involved in these conditions will help determine its origin and to detect problems on a population level. This dichotomous key proposed for the identification of abnormalities in pigmentation can be a continuous tool in modern research, st...

Recent models suggest a relationship exists between community diversity and pathogen prevalence, the proportion of individuals in a population that are infected by a pathogen, with most inferences tied to assemblage structure. Two contrasting outcomes of this relationship have been proposed: the "dilution effect" and the "amplification effect." Small mammal assemblage structure in disturbed habitats often differs from assemblages in sylvan environments, and hantavirus prevalence is often negatively correlated with habitats containing high species diversity via dilution effect dynamics. As species richness increases, prevalence of infection often is decreased. However, anthropogenic changes to sylvan landscapes have been shown to decrease species richness and/or increase phylogenetic similarities within assemblages. Between January 2011 and January 2016, we captured and tested 2406 individual small mammals for hantavirus antibodies at 20 sites across Texas and México and compared differences in hantavirus seroprevalence, species composition, and assemblage structure between sylvan and disturbed habitats. We found 313 small mammals positive for antibodies against hantaviruses, evincing an overall prevalence of 9.7% across all sites. In total, 40 species of small mammals were identified comprising 2 taxonomic orders (Rodentia and Eulipotyphla). By sampling both habitat types concurrently, we were able to make real-world inferences into the efficacy of dilution effect theory in terms of hantavirus ecology. Our hypothesis predicting greater species richness higher in sylvan habitats compared to disturbed areas was not supported, suggesting the characteristics of assemblage structure do not adhere to current conceptions of species richness negatively influencing prevalence via a dilution effect.

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Aberrant plumages in Mexican birds are rarely documented; in this work we report a record of partial leucism in the House Sparrow (Passer domesticus) in Cd. Victoria, Tamaulipas, Mexico. We discuss on the low incidence of this phenotypic alteration

La distribución geográfica de la tángara azul-gris (Thraupis episcopus) en hábitats modificados antropogénicamente en MéxicoResumen. Mediante trabajo de campo, la revisión de bases de datos biológicos e información de la distribución geográfica histórica y actual de Thraupis episcopus se establecieron nuevos registros de anidación en el noreste de México y su ampliación hacia hábitats modificados por actividades humanas en la península de Yucatán y el noreste de México. Además, se evaluó si existía preferencia de la especie por hábitats conservados vs. modificados, por medio de un análisis de escenarios de cambio de uso de suelo de 3 décadas diferentes (1970, 1980 y 1990), obteniendo porcentajes de presencia. Se encontró que no existe una diferencia significativa entre preferencias de hábitat a través del tiempo.Palabras clave: tángara azul-gris, áreas urbanas, registros de anidación, cambio de uso de suelo, expansión geográfica, este de México.Abstract. We analyzed the historical and current distributional range data of the Blue-gray Tanager, and reported new nesting records in northeastern Mexico. We also assessed the range extension of this species into human-altered habitats in the Yucatán Peninsula and northeastern Mexico, based both on records from fieldwork and biological databases. We identified habitat preference (conserved vs. human altered) using land use change scenarios from 3 decades (1970, 1980, and 1990) and percentages of occurrence in a multitemporal approach, finding no significant differences in habitat use through time.