Avifauna diversity assessment in the Communal Natural Protected Area El Gavilán, Central Coast of Oaxaca, Mexico

Tropical dry forest (TDF) is an ecosystem with a pronounced seasonality and high animal diversity. It is threatened by a wide variety of anthropogenic activities such as human population growth, deforestation rate, tourism development, forest fires, overhunting, and wildlife trade. One of the strategies for this biodiversity conservation is the creation of Communal Natural Protected Areas (CNPA), which are poorly explored. The aim of this study was to supply an assessment of the avian diversity in the CNPA El Gavilán on the Central Coast of Oaxaca (Mexico) during two seasons (dry and rainy). Sampling has been carried out at two localities (named as Centre and Mountain) between November 2018 and September 2019, using a point count method. At each locality, we sampled one transect varying in length, but with five-point counts separated by a minimum of 200 m. We made monthly two visits per transect. Birds were counted from a fixed raising position within a circle of 50-m radius for a specific period (10 min.) at every point. In total, 85 species were recorded, which belong to 65 genera, 24 families, and 13 orders. The most representative order was Passeriformes with 53 species. Most species (83) were considered very rare, and two species (Aratinga canicularis and Calocitta formosa) were rare. Regarding the avian diversity, 0D, the Centre locality had 74 species (19 exclusive species), while the Mountain locality had 65 species (11 exclusive species). The dry season had a higher diversity (Hʹ = 3.44) than the rainy season (Hʹ= 3.41), but there were no significant differences (Hutcheson t = 0.365, d.f. = 1, p > 0.05). Eighty-two percent (70 species) were considered residents, 15.3% (13 species) were winter migrants, 1.2% (one species) were summer migrants, and 1.2% (one species) were transient. Of the total registered taxa, 50 species were principally insectivorous, 14 species were grain-frugivorous, eight species were omnivorous, six species were carnivorous, and six species were nectarivorous. The avifauna of CNPA El Gavilán shows that a marked effect does not exist in the species composition between seasons. Due to the species richness recorded and estimated there, the study area should be considered in conservation policies, particularly because this territory is under intense pressure due to changes in land use.