PRIMER REGISTRO DE UNA ABERRACIÓN MARRÓN PARA EL CORMORÁN NEOTROPICAL NANNOPTERUM BRASILIANUM DE MÉXICO

En esta nota, reportamos un caso de aberración del plumaje en el cormorán neotropical Nannopterum brasilianum. Se registró la presencia de un color atípico en el plumaje de un individuo observado en un humedal del norte de México. El ave presentaba una aberración marrón, en la que el color negro original fue sustituido por tonos marrón claro y beige pálido. Observamos el ave alimentándose junto a otros cormoranes con una coloración normal y no mostró comportamientos diferentes. La documentación de fenotipos aberrantes es importante para determinar su frecuencia y patrones geográficos de aparición, especialmente en aves acuáticas con distribuciones geográficas extensas como N. brasilianum. Esta observación representa el primer reporte de aberración de plumaje marrón en esta especie

Variación fenotípica en palomas de collar (Streptopelia decaocto Frivaldszky) en Durango, México

Objective: To estimate the phenotypic variation of six external somatic variables (head length, beak, culmen, tarsal-metatarsal, wing and tail) in Eurasian Collared Dove. Design/methodology/approach: Head, beak, culmen, tarsal-metatarsal, wing and tail lengths were measured in Eurasian Collared Dove (n = 40). Kruskal-Wallis non-parametric analysis (z ? 1.96) and Guillaumin profiles were used to determine the influence of sex on each variable. The principal component analysis determined the degree of influence of each variable on the phenotypic variation of each variable. Results: The size of the structures analyzed were different between males and females. The tarsal-metatarsal, head and wing length were structures whose coefficient of variation was lower in both sexes (P ? 0.05). The principal component analysis explained from three components, 72.77% of the morphological variation. Limitations on study/implications: In the literature review, little information was found describing the morphological variation of birds (Streptopelia decaocto) in colonized and non-colonized environments. Findings/conclusions: The variables that present the greatest variation among individuals have a corneal component.Objetivo: Estimar la variación fenotípica de seis variables somáticas externas (longitud de cabeza, pico, culmen, tarso-metatarso, ala y cola) en Streptopelia decaocto Frivaldszky Diseño/metodología/aproximación: Se midieron las longitudes de cabeza, pico, culmen, tarso-metatarso, ala y cola en aves Streptopelia decaocto (n=40). Se utilizó el análisis no paramétrico de Kruskal-Wallis (z ? 1.96) y los perfiles de Guillaumin para determinar la influencia del sexo sobre cada variable. El análisis de componentes principales determinó el grado de influencia de cada variable sobre la variación fenotípica de cada variable. Resultados: Los tamaños de las estructuras analizadas fueron diferentes entre los machos y las hembras. La longitud del tarso-metatarso, de la cabeza y del ala, fueron estructuras cuyo coeficiente de variación fue menor en ambos sexos (P ? 0.05). El análisis de componentes principales explicó a partir de tres componentes, el 72.77% de la variación morfológica. Limitaciones del estudio/implicaciones: En la revisión de literatura se encontró poca información que describa la variación morfológica de las aves (Streptopelia decaocto) en ambientes colonizados y no colonizados. Hallazgos/conclusiones: Las variables que presentan mayor variación entre individuos tienen un componente córne

Avances científicos del búho manchado mexicano (Strix occidentalis lucida Nelson 1903)

Objective: Evaluate quantitatively the research trends of the Mexican Spotted Owl. Design/methodology/approach: Scientific articles published between 2012 and February 2020 for the Mexican spotted owl were analyzed. The content of each article was classified into nine categorical variables: 1) biological description, 2) habitat, 3) distribution and abundance, 4) dispersion and movement, 5) diet and prey, 6) genetics and reproduction, 7) threats, 8) predictive models and 9) others. The published information was classified into similar groups by means of a hierarchical cluster analysis. Subsequently, were calculated and graphed the frequency and proportional representation of each attribute generated by country. Results: Of the 23 scientific articles analyzed, the most studied attribute was habitat. The hierarchical cluster analysis grouped all the published information into five representative topics: a) habitat relationships, b) threats, c) distribution, d) bibliographic review and e) population relationship. The United States was the country with the highest scientific contribution. However, in the last three years of the period studied, publications in Mexico increased. Limitations on study/implications: This study analyzes the research trends of the Mexican spotted owl and provides an overview for future research. Findings/conclusions: There is little published information for this spotted owl subspecies. Although the characteristics of the habitat are widely described; it is necessary to venture into more complex ecological phenomena.Objetivo: Evaluar cuantitativamente las tendencias de la investigación del Búho Manchado Mexicano. Diseño/metodología/aproximación: Se analizaron los artículos científicos publicados entre 2012 y febrero de 2020 para el búho manchado mexicano. El contenido de cada artículo se clasificó en nueve variables categóricas: 1) descripción biológica, 2) hábitat, 3) distribución y abundancia, 4) dispersión y movimiento, 5) dieta y presas, 6) genética y reproducción, 7) amenazas, 8) modelos predictivos y 9) otros. La información publicada, se clasificó en grupos similares mediante un análisis de conglomerado jerárquico. Posteriormente, se calcularon y graficaron la frecuencia y representación proporcional de cada atributo generado por país. Resultados: De los 23 artículos científicos analizados, el atributo más estudiado fue el hábitat. El análisis de conglomerados jerárquicos agrupó toda la información publicada en cinco temas representativos:  a) relaciones del hábitat, b) amenazas, c) distribución, d) revisión bibliográfica y e) relación de las poblaciones. Estados Unidos fue el país con mayor contribución científica. Sin embargo, en los últimos tres años del periodo estudiado, las publicaciones en México incrementaron. Limitaciones del estudio/implicaciones: Este estudio analiza las tendencias de investigación del búho manchado mexicano y permite establecer un panorama para investigaciones futuras. Hallazgos/conclusiones: Existe poca información publicada para esa subespecie de búho manchado. Aunque las características del hábitat son ampliamente descritas; es necesario incursionar en fenómenos ecológicos más complejos

Effect of annual rainfall and temperature on the selection of habitat and overwintering home range of grassland birds

Objective: To determine the effect of annual precipitation and winter temperature on habitat and winter home range size of two grassland birds in a native grassland of northern Durango, Mexico. Design/methodology/approach: Using telemetry techniques over four consecutive winters (2016-2019), we estimated the home range size (HR; by Kernel method), of Centronyx bairdii and Ammodramus savannarum. Likewise, we estimated the cover of grass, bush, grass, bare ground, dead vegetation, animal excrement and counted the seeds available in the soil (biomass, gr/m2) of the habitat. We compared these dependent variables with non-parametric statistics, with the minimum and maximum annual precipitation (mm) and temperature (°C) of the site. Results: The grassland sparrows used sites with equal coverage of grass, herbaceous plants, shrubs, bare ground, and others (Kruskal-Wallis, p≤0.05). In general, annual rainfall has no effect on the structure and vegetation cover. HR was negatively correlated (Sperman, p≤0.05) with annual rainfall for C. bairdii (rs=-0.90, n=45) and for A. savannarum (rs=-0.80, n=33). When the maximum temperature was higher, both species had a smaller HR. In contrast, when the minimum temperature was low, the HR increased for C. bairdii and decreased for A. savannarum. Study limitations/implications: We demonstrate the importance of considering quantifying the largest number of variables when research is required on the selection and use of grassland bird habitat. Findings/conclusions: This study allows us to increase our knowledge about the winter ecology of grassland birds and demonstrates that environmental variables such as annual rainfall and temperature influence habitat selection of C. bairdii and A. savannarum.Objective: To determine the effect of annual precipitation and winter temperature on the habitat and size of the overwintering home range of two grassland birds in a native grassland in northern Durango, Mexico. Design/ Methodology/ Approach: Using telemetry techniques during four consecutive winters (2016-2019), we estimated the size of the home range (HR; by the Kernel method) of Centronyx bairdii and Ammodramus savannarum. Likewise, the coverage of grassland, scrubland, bare soil, dead vegetation, and animal excrement was estimated and the seeds available in the soil (biomass, g m-2) of the habitat were counted. We correlated these dependent variables with non-parametric statistics, to the minimum and maximum annual rainfall (mm) and temperature (°C) of the site. Results: Grassland sparrows used sites with equitable cover of grass, herbaceous plants, shrubs, bare soil and others (Kruskal-Wallis, p≤0.05). Overall, annual precipitation has no effect on structure and vegetation cover. The HR was negatively correlated (Spearman, p≤0.05) with the annual precipitation for C. bairdii (rs=-0.90, n=45) and for A. savannarum (rs=-0.80, n=33). When the maximum temperature was higher, both species had lower HR. In contrast, when the minimum temperature was low, the HR increased for C. bairdii and decreased for A. savannarum. Study Limitations/ Implications: We demonstrated the importance of considering quantifying the greatest number of variables when research is required on the selection and use of grassland bird habitat. Findings/ Conclusions: This study allowed us to increase our knowledge about the winter ecology of grassland birds and demonstrated that environmental variables such as annual precipitation and temperature influenced the habitat selection of C. bairdii and A. savannarum

Development of an application for the differentiation of the genus of Baird’s sparrow (Centronyx bairdii) based on an artificial neural network: Baird's sparrow sexing using a computer application

Objective: Develop a computer application with the possibility of being used in the field with high reliability to differentiate the sex of sparrows of the species Centronyx bairdii. Design/methodology/approach: A previously developed artificial neural network was used to predict the sex of C. bairdii individuals. This algorithm was installed in an application developed using the MATLAB GUIDE environment for building graphical user interfaces. Results: The computer application developed allows the introduction of morphometric data of individuals and predicts their sex with a confidence level of 92.3%. Study limitations/implications: To install and run the application it is necessary to have a Windows operating system version 7 or later versions and the Matlab Ver. 7.5.0 program. Findings/conclusions: Through the computational application generated here, it is possible to determine the genus of the species Centronyx bairdii with an accuracy of 92.3%. This is a useful tool for sexing birds of this species in the field.Objective: To develop a computer application with the possibility of being used in the field with high reliability to differentiate the sex of sparrows of the species Centronyx bairdii. Design/Methodology/Approximation: A previously developed neural network was used to predict the sex of C. bairdii individuals. This algorithm was installed in an application developed using the MATLAB GUIDE environment for using graphic user interfaces. Results: The computer application developed allows the introduction of morphometric data of individuals and predicts their sex with a confidence level of 92.3%. Study Limitations/Implications: To install and run the application it is necessary to have a Windows version 7 operating system or later versions and the Matlab Ver. 7.5.0 software. Findings/Conclusions: Through the computational application generated, it is possible to determine the genus of the species Centronyx bairdii with an accuracy of 92.3%. This is a useful tool for sexing birds of this species in the field

Seasonal abundance of waterfowl for hunting in the southern portion of the Malaga wetland, Durango, Mexico

Objective: Estimate the composition and winter abundance of waterfowl of hunting interest in a Management Unit for the Conservation of Wildlife (MUCW), within the Malaga wetland complex, Durango, Mexico. Design/methodology/approach: In the winter of 2019, we identified and quantified the waterfowl of hunting interest in an MUCW of the Malaga wetland complex, Durango, Mexico. We performed the counts with fixed points in five repetitions to estimate the specific richness and abundance of birds. We compared these variables using the Kruskal-Willi’s test (P<0.05). Results: We registered 21,620 waterfowl of 18 species. The most frequent families were the Anatidae, Rallidae and Gruidae. The species Anser albifrons, A. caerulescens and Anas crecca were the most abundant. This abundance increased according to the number of recordings, being the last one, where the highest proportion of waterfowl was produced (P<0.05). Study limitations/implications: This study provides baseline demographic information for this group of birds that inhabit the wetlands of Durango. However, to determine the demographic dynamics of these species, it is necessary to carry out long-term monitoring. Findings/conclusions: This research allows us to recognize the study site as diverse and important for hunting waterfowl that winter in Durango, Mexico.Objective: To estimate the composition and winter abundance of waterfowl for hunting in a Wildlife Conservation Management Unit (UMA), within the Malaga wetlands complex, Durango, Mexico. Design/Methodology/Approach: In the winter of 2019, waterfowl for hunting were identified and quantified in an UMA of the Malaga wetlands complex, Durango, Mexico. The birds were counted with the point count methodology in five repetitions, in order to estimate their specific richness and abundance in each one. These variables were compared using the Kruskal-Wallis test (p < 0.05). Results: A total of 21,620 birds from 18 species were registered. The most frequent families were the Anatidae, Rallidae, and Gruidae. Anser albifrons, A. caerulescens, and Anas crecca were the most abundant species. This abundance increased according to the number of tests. Therefore, the highest proportion of birds was recorded in the last sampling (p < 0.05). Study Limitations/Implications: This study provides baseline demographic information for this group of birds that inhabits the Durango wetlands. However, long-term monitoring is necessary to determine the demographic dynamics of these species. Findings/Conclusions: The study site is diverse and important for the waterfowl for hunting that spend the winter in Durango, Mexic