Riqueza y conservación de las aves del suroeste de Oaxaca

La vertiente del Pacífico mexicano en el suroeste de Oaxaca alberga una gran diversidad de aves que ha sido poco estudiada. Presentamos un inventario y análisis de la avifauna de esa región, mediante transectos, redes de niebla y observaciones no sistemáticas, en 12 localidades repartidas en cuatro tipos de vegetación (selva mediana subcaducifolia, vegetación ribereña, áreas sujetas a manejo agropecuario y selva baja caducifolia). Contabilizamos 120 especies, correspondientes a 39 familias y 19 órdenes. Del total de especies, 72% fueron residentes todo el año y 24%, de invierno. Por el tipo de alimentación, las terrestres insectívoras (52%) fueron las más abundantes, seguidas de las carnívoras (20%) y terrestres herbívoras (15%). El mayor número de especies (68%) estuvo asociado a vegetación ribereña. Esta región de Oaxaca alberga 16% de la riqueza de aves de México, entre ellas a nueve especies endémicas o cuasiendémicas de México y 12 en categorías de riesgo a nivel nacional o internacional, como el pato real (Cairina moschata), loro corona lila (Amazona finschi), loro cabeza amarilla (Amazona oratrix) y vireo de Bell (Vireo bellii). Recomendamos la protección de la vegetación ribereña y de las selvas como la mejor estrategia para la conservación de la avifauna.

The relationship between forest fragmentation and the potential geographical distribution of psittacids (Psittaciformes: Psittacidae) in the Yucatan Peninsula, Mexico

Parrots are a seriously threatened group because of the illegal pet trade, their habitat fragmentation and the destruction of tropical forests. This study aimed to determine the relationship between forest fragmentation and the geographic potential distribution of parrot species in the Yucatan Peninsula, Mexico. The research was carried out in the Mexican portion of the Yucatan Peninsula Biotic region, which includes the states of Campeche, Quintana Roo and Yucatan. We worked with the eight species of psittacids that inhabit the selected areas: Eupsittula nana, Amazona albifrons, Amazona xantholora, Amazona autumnalis, Pionus senilis, Pyrilia haematotis, Amazona oratrix and Amazona farinosa. For these species, we used the potential geographical distribution maps that were obtained through the Maximum Entropy algorithm, published in 2014. To measure the levels of forest fragmentation in the Peninsula, we employed the land use and vegetation maps from series IV (2007-2010) of the National Institute of Statistics and Geography. We calculated different landscape metrics at 100 sites randomly distributed within the predicted presence and absence areas for the species. Multivariate methods were used to shorten dimensionality in the analysis, as well as to explore the observed patterns. We did not find any pattern regarding the number of variables that contribute to the logistic regression models (LR) and the size of the parrots’ potential geographical distribution area within the Peninsula. For Pyrilia haematotis and Amazona oratrix, the fragmentation variables used did not seem to have any relationship with their potential geographical distribution in the Peninsula (intersection, Pr < 0.0001). Only for Eupsittula nana, Amazona xantholora and Pionus senilis, we found that the mean patch edge, the mean shape index and the mean perimeter-area ratio were important to determine their potential distribution patterns, respectively; and, in general, the variables indicated the preferences of these parrots to occupy larger habitat patches. Parrots must be given a special care and protection within the states of Campeche and Quintana Roo, since there are areas with high parrot diversity and are importantly affected by human activities. The best recommendation for managers and users of protected areas within the Yucatan Peninsula is that extensive areas of forest should be maintained in order to guarantee the suvival of psittacid populations.