Abundancia, distribución espacial y temporal de aves playeras (Orden: Charadriiformes) en Marismas Nacionales, México

El noroeste de México alberga las mayores abundancias de aves playeras del país. Sin embargo, para muchos de estos humedales, información sobre comunidades de aves playeras, como abundancia, tendencias poblacionales y riqueza es limitada. Actualmente, los sitios de descanso son críticos para la conservación porque las poblaciones de aves playeras han decaído en las últimas décadas. Marismas Nacionales (MN) es un humedal tropical importante con un ecosistema dinámico donde los estudios de aves playeras están limitados a unos pocos censos aéreos y terrestres. Así el objetivo del trabajo fue describir la abundancia y distribución espacial y temporal de las aves playeras en MN (temporada 2010-2011). Se seleccionaron ocho unidades de muestreo en las que se llevaron a cabo censos mensuales (noviembre 2010 a junio 2011). Se determinaron las riquezas y abundancias por sitio-mes, además se realizó un análisis espacial y temporal de las especies dominantes. Se registraron 27 especies de aves playeras y un género, con un estimado mínimo de 136 236 individuos. Este número hace a MN uno de los humedales prioritarios para la conservación en México, pues alberga al 10 % de la abundancia general del noroeste. Las especies dominantes fueron el Playerito occidental (Calidris mauri, 33 % del total), la Avoceta americana (Recurvirostra americana, 31 %) y los Costureros (Limnodromus spp., 17 %). Espacialmente las lagunas de mayor importancia fueron: Chumbeño (37 % del total registrado), Las Garzas-Chahuin (24 %) y La Polca (24 %). Este trabajo actualiza la información sobre aves playeras que utilizan MN y podría permitir el establecimiento de un programa de monitoreo, lo cual es prioritario sobre todo porque el área es un Sitio de Importancia Internacional por parte de la Red Hemisférica de Reserva para las Aves Playeras.

Northwest Mexico is an important region for shorebirds associated with an extensive series of wetlands. However, for many of these wetlands, basic information about shorebirds communities like abundance, population trends, and richness are limited. Currently, wintering and stopover sites are critical for conservation because many populations of shorebirds have declined in the last decades. Marismas Nacionales (MN) is an important tropical wetland with a dynamic ecosystem and where shorebirds studies are limited to few wintering aerial and ground surveys. Our goals were analyzing shorebirds abundance and spatial and temporal distribution patterns in 2010-2011 season. We selected eight monitoring sites from two prospective visits to the study area. We observed shorebirds monthly between November 2010 and June 2011 to analyze richness and abundance patterns by site and month. Additionally, we describe specific spatial and temporal distribution for dominant species. A total of 27 shorebirds species and one genus, with a minimum global abundance of 136 236 individuals were found. Shorebird abundance at MN is among the most important in the region with around 10 % of total abundance in northwest Mexico; therefore, MN is a priority conservation site for this group of birds. Additionally, MN presents a suitable habitat for breeding of some shorebirds species such as Snowy and Wilson' Plover, Killdeer, Northern Jacana, Black-necked Stilt and Pacific American Oystercatcher. Dominant species were: Western Sandpiper (33.5 % of total in MN), American Avocet (31 %) and Dowitchers (17 %). These taxa are very common in others wetlands in Northwest Mexico region. Spatially, shorebirds were distributed in three sites: Chumbeño lagoon (37 % of abundance total), Las Garzas-Chihuin lagoons (24.2 %) and La Polca lagoon (24 %). The less used sites by shorebirds are located in the southern part of MN. Our results update MN information and can help to establish monitoring programs in the area.

Tropical forest remnants as shelters of avian diversity within a tourism development matrix in Yucatan Peninsula, Mexico / Remanentes de bosque tropical como refugios de la diversidad de aves dentro de una matriz de desarrollo turístico en la Península de Yucatán, México

Abstract Tropical forests have undergone extensive transformation because of increasing tourism development, in addition to historic clearing for agricultural and cattle grazing activities. Altogether, these activities have had an important effect on bird diversity, reducing the habitat available to many species. In this study, the role of tropical forest remnants located between different land use types was evaluated for species diversity, composition, and distribution of the bird community at Akumal region in Quintana Roo, Mexico. Point counts were used to quantify the avifauna by habitat, and Shannon´s and Simpson´s diversity index were used to determine bird diversity. Additionally, bird species were classified according to seasonality and trophic guild by type of habitat. A total of 160 species and 50 families was recorded, of which 100 species were permanent residents, 47 winter visitors and 11 transients. Mature tropical forest and tropical forest remnants had higher species richness than those of modified environments. This study supports the importance of tropical forest remnants as shelters for bird species in landscapes with tourism developments, and the relevance of these remnants to maintaining high bird diversity. Rev. Biol. Trop. 66(2): 799-813. Epub 2018 June 01.

Resumen Los bosques tropicales han sufrido una transformación extensa debido al aumento de los desarrollos turísticos, además de la compensación histórica de las actividades agrícolas y de pastoreo del ganado. En conjunto, estas actividades han tenido un efecto importante en la diversidad de aves, reduciendo el hábitat disponible para muchas especies. En este estudio, se evaluó el papel de los remanentes de bosque tropical para la diversidad de especies y composición de la comunidad de aves ubicados en diferentes tipos de uso de suelo en la región de Akumal en Quintana Roo, México. Se utilizaron puntos de conteo para caracterizar la avifauna por hábitat, y se utilizó el índice de diversidad de Shannon y Simpson para determinar la diversidad de aves. Además, las especies de aves se clasificaron según la estacionalidad y el gremio alimenticio. Se registraron 160 especies, distribuidas entre 50 familias; 100 especies fueron residentes permanentes, 47 visitantes de invierno y 11 transitorias. El bosque tropical maduro y remanentes de bosque tropical tuvieron una mayor riqueza de especies y valores de diversidad que los ambientes modificados. La composición de las especies de aves de los remanentes de bosque tropical fue similar a la del bosque tropical maduro, pero mayor que los ambientes modificados. Este estudio demuestra la importancia de los remanentes forestales tropicales como refugios y corredores biológicos en paisajes con desarrollos turísticos, y la relevancia de estos remanentes en el mantenimiento de una alta diversidad de aves.

Heterogeneity of bird communities in a mosaic of habitats on a restinga ecosystem in southeast Brazil

Restinga occurs as a narrow band of coastal habitats throughout the Atlantic Forest, although it presents considerable variation in vegetation structure, which likely contributes to heterogeneity in species inhabiting this endangered ecosystem. The goal of this study is to examine how variation in vegetation and abiotic conditions in the restinga ecosystem may contribute to heterogeneity of bird communities in Restinga de Jurubatiba, Brazil. Temperature, relative humidity, and vegetation structure were sampled to characterize four sites (dry forest, flooded forest, open scrub and closed scrub). Birds were sampled using observations, mist-netting and voice recordings. Results indicate that major differences of all variables occur between forest and scrub in both vegetation and birds. In addition, differences also exist within forests and within scrub, resulting in considerable heterogeneity among sampled areas. Scrub sites were richer in bird species (n = 58) than forest sites (n = 41), while closed scrub had the most species (n = 49). Also, 64% (47 of 73) of bird species were exclusive to forest or scrub habitats. Scrub habitats were more similar to each other than forest habitats. Normalized Difference Vegetation Index (NDVI) calculated from satellite images distinguished scrub sites and may be useful to monitor changes in vegetation patches through time. The restinga ecosystem is quite heterogeneous with considerable turnover in bird species composition and differences in vegetation structure. Forest strips may serve as connectors on the landscape and to help maintain species diversity and conservation of forest species. Also, this highly dynamic ecosystem, which includes a mosaic of habitat types, likely promotes resilience of bird populations under changing conditions.(AU)

Heterogeneity of bird communities in a mosaic of habitats on a restinga ecosystem in southeast Brazil

Restinga occurs as a narrow band of coastal habitats throughout the Atlantic Forest, although it presents considerable variation in vegetation structure, which likely contributes to heterogeneity in species inhabiting this endangered ecosystem. The goal of this study is to examine how variation in vegetation and abiotic conditions in the restinga ecosystem may contribute to heterogeneity of bird communities in Restinga de Jurubatiba, Brazil. Temperature, relative humidity, and vegetation structure were sampled to characterize four sites (dry forest, flooded forest, open scrub and closed scrub). Birds were sampled using observations, mist-netting and voice recordings. Results indicate that major differences of all variables occur between forest and scrub in both vegetation and birds. In addition, differences also exist within forests and within scrub, resulting in considerable heterogeneity among sampled areas. Scrub sites were richer in bird species (n = 58) than forest sites (n = 41), while closed scrub had the most species (n = 49). Also, 64% (47 of 73) of bird species were exclusive to forest or scrub habitats. Scrub habitats were more similar to each other than forest habitats. Normalized Difference Vegetation Index (NDVI) calculated from satellite images distinguished scrub sites and may be useful to monitor changes in vegetation patches through time. The restinga ecosystem is quite heterogeneous with considerable turnover in bird species composition and differences in vegetation structure. Forest strips may serve as connectors on the landscape and to help maintain species diversity and conservation of forest species. Also, this highly dynamic ecosystem, which includes a mosaic of habitat types, likely promotes resilience of bird populations under changing conditions.