Association between Landscape Features and Owl Assemblages in a Tropical Rainforest of Southeastern Mexico
Tropical owls are one of the most threatened groups of birds. Studying the association between landscape features and owl assemblages is challenging due to the logistical difficulties of nocturnal fieldwork. We analyzed the association of landscape composition and spatial configuration of forest cover with the composition of the owl assemblages in a tropical rainforest in southeastern Mexico. During the 2014 reproductive season (April to June), we estimated owl abundance through auditory detection and playbacks at 60 survey points distributed in 12 landscapes (625 ha each) within a gradient of forest cover. We found that the owl community comprised six out of the 10 expected resident species. The landscape unit with 41% forest cover contained the most diverse assemblage. The owl species most susceptible to local extinction were specialists of interior areas of old-growth forest. The abundances of the Middle American Screech-Owl (Megascops guatemalae), Great Horned Owl (Bubo virginianus), and Black-and-white Owl (Ciccaba nigrolineata) were positively associated with the proportion of forest cover as well as with the average size of the patches, but negatively associated with environmental temperature. The abundances of the Barn Owl (Tyto alba) and Ferruginous Pygmy-Owl (Glaucidium brasilianum) were positively related to the amount of urban area in the landscape. The only species recorded along the entire gradient was the Mottled Owl (Ciccaba virgata), a species that is a generalist in habitat and diet; its abundance was positively related to the proportion of forest cover and the amount of water surface (lakes and rivers) in the landscape. Four resident species were not recorded: Crested Owl (Lophostrix cristata), Spectacled Owl (Pulsatrix perspicillata), Striped Owl (Pseudoscops clamator), and Central American Pygmy-Owl (Glaucidium griseiceps). Asociación Entre las Características del Paisaje y los Ensambles de Búhos en un Bosque Tropical del Sureste de México Los búhos tropicales constituyen uno de los grupos de aves más amenazados. Estudiar su asociación con las características del paisaje representa un desafío dadas las dificultades logísticas que implica el trabajo nocturno en el campo. Analizamos la asociación de la composición del paisaje y la configuración espacial de la cobertura forestal con la composición de los ensambles de búhos en un bosque tropical húmedo en el sureste de México. Durante la temporada reproductiva (abril a junio 2014), estimamos la abundancia de los búhos mediante detección auditiva y reclamos en 60 puntos de conteo distribuidos en 12 paisajes de 625 ha cada uno que conformaron un gradiente de cobertura forestal. Nuestros resultados muestran que la comunidad de búhos estuvo constituida por seis de las 10 especies residentes esperadas. El paisaje con 41% de cobertura forestal presentó el ensamble más diverso. Las especies más susceptibles a sufrir extinción local son especialistas que habitan el interior del bosque maduro. La abundancia de Megascops guatemalae, Bubo virginianus y Ciccaba nigrolineata estuvo asociada positivamente con la proporción de cobertura forestal y con el tamaño promedio de los parches, pero negativamente asociada con la temperatura ambiental. La abundancia de Tyto alba y Glaucidium brasilianum estuvo asociada positivamente con el área urbana en el paisaje. La única especie registrada a lo largo de todo el gradiente fue Ciccaba virgata, una especie generalista de hábitat y de dieta. Sin embargo, su abundancia estuvo asociada positivamente con la proporción de cobertura forestal y con la superficie de agua en el paisaje. Cuatro especies residentes, Lophostrix cristata, Pulsatrix perspicillata, Pseudoscops clamator y Glaucidium griseiceps no fueron registradas en este estudio. [Traducción de los autores editada]ABSTRACT
RESUMEN
Map of study area and study landscapes in Los Tuxtlas Biosphere Reserve, Veracruz, Mexico. The black line depicts the limit of the biosphere reserve. The dotted gray lines within the biosphere reserve represent the grid used for the selection of the study landscapes. The inset in the upper right corner is a close-up of one of the study landscapes (Identification number: 11). The identification number of each landscape is the same as in Table 1.
Accumulation curve of owl species detected in the 12 landscapes surveyed. We constructed this curve using individual-based abundance data to confirm the effectiveness of the sampling effort. We used the EstimateS 9.1.0 program and determined that survey completeness was 91%. The black line represents the observed species, the gray line is the nonparametric Chao estimator, and the dotted lines depict the 95% confidence intervals.
Abundance of owl species in the 12 study landscapes within a gradient of tropical rainforest cover in Los Tuxtlas Biosphere Reserve, Veracruz, Mexico. (A) Forest interior species: Middle American Screech-Owl (Megascops guatemalae), Great Horned Owl (Bubo virginianus), and Black-and-white Owl (Ciccaba nigrolineata). (B) Interior and forest edge species: Mottled Owl (Ciccaba virgata). (C) Forest edge and open area species: Barn Owl (Tyto alba) and Ferruginous Pygmy-Owl (Glaucidium brasilianum).
Assemblages of owl species per landscape in the Los Tuxtlas Biosphere Reserve. The filled squares represent the presence of the species in each landscape. The color of the squares represents the habitat associations of species as reported by Schaldach and Escalante-Pliego (1997) and Lee and Meerman (2015): black=forest interior; dark gray=forest interior and forest edge; light gray = forest edge and open areas.
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