Abstract Background Characterizations of the dynamics of hybrid zones in space and time can give insights about traits and processes important in population divergence and speciation. We characterized a hybrid zone between tanagers in the genus Ramphocelus (Aves, Thraupidae) located in southwestern Colombia. We tested whether this hybrid zone originated as a result of secondary contact or of primary differentiation, and described its dynamics across time using spatial analyses of molecular, morphological, and coloration data in combination with paleodistribution modeling. Results Models of potential historical distributions based on climatic data and genetic signatures of demographic expansion suggested that the hybrid zone likely originated following secondary contact between populations that expanded their ranges out of isolated areas in the Quaternary. Concordant patterns of variation in phenotypic characters across the hybrid zone and its narrow extent are suggestive of a tension zone, maintained by a balance between dispersal and selection against hybrids. Estimates of phenotypic cline parameters obtained using specimens collected over nearly a century revealed that, in recent decades, the zone appears to have moved to the east and to higher elevations, and has apparently become narrower. Genetic variation was not clearly structured along the hybrid zone, but comparisons between historical and contemporary specimens suggested that temporal changes in its genetic makeup may also have occurred. Conclusions Our data suggest that the hybrid zone likey resulted from secondary contact between populations. The observed changes in the hybrid zone may be a result of sexual selection, asymmetric gene flow, or environmental change.
Objectives: To conduct a bird inventory at the Barcelona campus of Universidad de los Llanos Villavicencio, Colombia, with the aim of estimating species richness, abundance and habitat associations of the local avifauna. Scope: Characterization of the local avian diversity and its association with different types of natural and transformed ecosystems. Methodology: We inventoried birds using sight and auditory records made weekly between August 2013 and August 2014, plus opportunistic observations made between 2013 and 2018. We estimated species richness using non-parametric estimates, and categorized local abundances and habitat associations based upon encounter frequencies. Main results: We recorded a total of 210 species (189 species through systematic observations, plus 21 recorded non-systematically). The list includes one Colombian near-endemic, 20 migrant species, and four range extensions for the Orinoco basin. The heterogeneous vegetation sustains a rich community composed mainly by species associated with urban zones, gallery forest and artificial lakes. Most species were rare and occasional, which suggests that they are visitors or maintain small populations within the campus. Conclusions: This study provides basic data on bird diversity of transformed ecosystems in the Orinoco basin, and highlights the importance of mosaics of savanna, forest and transformed ecosystems as refuges and stopover areas of resident and migratory birds.
Abstract Context The patch-mosaic model (PMM) is the most common way to describe the landscape in ecological research. Despite this, the gradient model (GM) was proposed as a more accurate representation of the heterogeneity of landscapes; however, little has been explored on the behavior and performance of continuous variables and surface-based metrics from GM under different analytical scenarios. Objectives We address the question: which landscape metrics, patch-based or surface-based, best explain habitat occupancy patterns of six bird species with different ecological preferences? Methods We generated detection histories for six bird species in a fragmented Andean landscape from Colombia. We obtain patch-based metrics from a land cover classification and surface-based metrics from the principal polar spectral indices (PPSi) to describe the landscape. Finally, we fitted dynamic occupancy models using variables derived from landscape models and compared their performance using quasi-AIC for each species. Results We obtained 909 detections for the six selected bird species. We found that PPSi and surface-based metrics were more informative when assessing occupancy patterns for five of the six species studied. In addition, surface-based metrics allowed to detect interspecific differences between species beyond an affinity for a particular cover type. Conclusions Surface-based metrics can be an alternative for assessing species response to landscape heterogeneity, particularly those that may be more sensitive to fine-scale changes in vegetation cover. However, there is no single “best” model to describe the landscape for all cases. PPSi can be very useful for land cover analysis in landscape ecology studies as an alternative to more popular vegetation indices.
Baseline information is a priority for conservation plans of protected areas, especially when they are of great importance for the maintenance of biodiversity. In order to increase the knowledge about Fuquene River watershed (Cundinamarca, Colombia), we carried out a characterization of the avifauna with local communities. We visited the area eight times (May-August 2012), covering 15 observation points in different land covers: Grassland and paramo, riparian forest, high Andean forest, low Andean forest, dense scrub, and plantation. We found 53 species of birds, of which two are endemic to Colombia: Silvery-throated Spinetail ( Synallaxis subpudica ), found in four types of habitats, and the Rufous-browed Conebill ( Conirostrum rufum ), found only in Andean forest. The avifauna recorded in this study, is an indicator of the importance of the forest cover in a landscape transformed and base line to establish the management tools.
New localities for the Carib Grackle (Quiscalus lugubris) in Colombia are detected, records for the Caribbean coast of Colombia come from the departments of Magdalena and La Guajira. The records are obtained in the birds in Tropical dry Forests and coastal wetlands monitoring program. The range extension of populations are an indicator of the deterioration of the natural ecosystems of the region, according to the anthropophily of the species.
Registramos el paisaje sonoro en cuatro fincas ganaderas en el piedemonte llanero del departamento del Meta, Colombia. Se utilizaron ocho grabadoras acústicas, cuatro en silvopastoriles de potreros arbolados y cuatro en sistemas de ganadería tradicional. Cada grabadora estuvo grabando 1 minuto cada 10 minutos, durante un promedio de 4 días, en noviembre de 2019. Se obtuvieron 4743 grabaciones de un minuto, 57.3% para sistemas de potreros tradicionales y 42.7% para potreros arbolados. Se encontraron diferencias en la actividad acústica y el uso del espacio acústico, el cual está relacionado a la distancia a las quebradas. Las variables distancia a vías y a quebradas explicaron la variación de riqueza de aves y anuros, la cual fue menor para potreros arbolados en relación a los potreros tradicionales, lo que puede estar relacionado con el diseño del sistema silvopatoril (monocultivo de falso yopo, Mimosa trianae). Futuras iniciativas silvopastoriles deberían incluir diseños más diversos para poder contrastar el tipo de métricas evaluadas en este estudio.
Abstract Context: The patch-mosaic model (PMM) is the most common way to describe the landscape in ecological research. Despite this, the gradient model (GM) was proposed as a more accurate representation of the heterogeneity of landscapes; however, little has been explored on the behavior and performance of continuous variables and surface-based metrics from GM under different analytical scenarios.Objectives: We address the question: which landscape metrics, patch-based or surface-based, best explain habitat occupancy patterns of six bird species with different ecological preferences?Methods: We generated detection histories for six bird species in a fragmented Andean landscape from Colombia. We obtain patch-based metrics from a land cover classification and surface-based metrics from the principal polar spectral indices (PPSi) to describe the landscape. Finally, we fitted dynamic occupancy models using variables derived from landscape models and compared their performance using quasi-AIC for each species.Results: We obtained 909 detections for the six selected bird species. We found that PPSi and surface-based metrics were more informative when assessing occupancy patterns for five of the six species studied. In addition, surface-based metrics allowed to detect interspecific differences between species beyond an affinity for a particular cover type.Conclusions: Surface-based metrics can be an alternative for assessing species response to landscape heterogeneity, particularly those that may be more sensitive to fine-scale changes in vegetation cover. However, there is no single “best” model to describe the landscape for all cases. PPSi can be very useful for land cover analysis in landscape ecology studies as an alternative to more popular vegetation indices.
El habia ceniza (Habia gutturalis) y el torito capiblanco (Capito hypoleucus) son aves amenazadas y endémicas de Colombia. Ambas especies tienen rangos geográficos y tamaños poblacionales pequeños posiblemente como resultado de la destrucción y fragmentación de sus hábitats. Con el fin de obtener estimados cuantitativos de los efectos de características del paisaje sobre la ocupación de ambas especies, muestreamos una variedad de configuraciones del paisaje al interior de las zonas de amortiguamiento de dos hidroeléctricas en la cordillera Central de los Andes de Colombia y empleamos modelos de ocupación para estimar la proporción del área ocupada en función de estas covariables. Realizamos 35 puntos de conteo en cada zona de amortiguamiento entre junio y julio del 2014 y 2015. Utilizamos modelos de ocupación de una sola temporada para estimar la ocupación reconociendo la detección imperfecta. Los promedios de ocupación para ambas especies en el área de estudio fueron similares (0.61 SD=0.33 para el habia ceniza y 0.63 SD=0.25 para el torito capiblanco). Sin embargo, la distribución de la ocupación al interior del área de estudio fue muy diferente entre ellas. El mejor modelo para la habia ceniza propone que su ocupación disminuye con la elevación, mientras que el mejor modelo para la ocupación del torito capiblanco propone un aumento en la ocupación con la distancia a quebradas. Las probabilidades de detección fueron similares para ambas especies (<0.4) y declinaron significativamente durante el segundo año. Nuestros resultados proveen lineamientos cuantitativos para evaluar y monitorear el estado de estas poblaciones a corto y largo plazo.
Se presentan nuevas localidades para el Chango Llanero (Quiscalus lugubris) en Colombia, los primeros registros para la costa Caribe de Colombia provienen de los departamentos del Magdalena y La Guajira. Los registros son resultado del monitoreo de avifauna en Bosques secos Tropicales y Humedales costeros. La ampliacion del rango de distribucion de las poblaciones es indicador del deterioro que han sufrido los ecosistemas naturales de la region, dada la antropofilia de la especie.
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