RESUMO
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.
RESUMO
This study was conducted to investigate the effects of melatonin implantation on basic testicular characteristics and reproductive performance of Kivircik and Charollais rams and ewes during the non-breeding season. In this study, 8 Kivircik and 6 Charollais rams were used. Rams were implanted with 54 mg melatonin according to the manufacturer's instructions. At melatonin implantation and at ram introduction the reproductive performance and testicular characteristics were evaluated. Throughout the experimental period, rams were permanently kept outdoors under conditions of natural day length and at ambient temperature. The effects of exogenous melatonin treatments on the reproductive performances of rams and ewes, estrus response, pregnancy rate, litter size and twinning rate of ewes were evaluated in all groups. Libido values were significantly higher in Charollais rams compared to Kivircik rams (P<0.001). Testicular volume (TV) was increased in both ram breeds. Scrotal length (SL) was also increased in both Kivircik and Charollais rams (P<0.01). In conclusion, we showed that the treatment of rams with slow release melatonin implants increased scrotal diameters and testicular volumes in both Kivircik and Charollais rams. Furthermore, melatonin implantation improved the reproductive performances of ewes naturally mated with these melatonin implanted rams during non-breeding season.(AU)
Esse estudo foi conduzido para investigar os efeitos de implantação de melatonina em características testiculares básicas e desempenho reprodutivo de carneiros Kivircik e Charollais durante a estação não reprodutiva. Nesse estudo, oito carneiros Kivircik e 6 Charollais foram utilizados. Foi implantado 54 mg de melatonina nos cordeiros de acordo com as instruções do produtor. Ao implantar a melatonina e à introdução do carneiro, foram avaliados o desempenho reprodutivo e as características testiculares. Ao longo do período experimenta, os cordeiros foram mantidos em ambiente externo sob condições de luz e ritmo circadiano naturais e à temperatura ambiente. O efeito de tratamento com melatonina exógena no desempenho reprodutivo de carneiros e ovelhas, resposta estral, taxa de prenhez, tamanho de ninhada e taxa de gemelaridade foram avaliados em todos os grupos. Valores de libido foram significativamente maiores em Charollais comparados a Kivircik (P<0.001). Volume testicular (VT) estava aumentado em ambas as raças. Comprimento escrotal (CE) também estava aumentado tanto em Kivircik quanto em Charollais (P<0.01). Conclui-se que o tratamento de carneiros com implantes de liberação lenta de melatonina aumentou diâmetro e volume testiculares tanto em carneiros Kivircik quanto em Charollais. Ademais, implantação de melatonina melhorou o desempenho reprodutivo de ovelhas naturalmente cruzadas com esses carneiros implantados com melatonina durante o período não reprodutivo.(AU)