Cruzando o desviando los Andes: un comentario sobre extensiones de distribución recientes de aves cis-Andinas al oeste de los Andes de Colombia.

Jorge E. Avendaño,Diego A. Rincón-Guarín,Elkin R. Briceño-Lara,José O. Cortés-Herrera

doi:10.22579/20112629.18

Abstract

Título en ingles: Crossing or bypassing the Andes: a commentary on recent range extensions of cis-Andean birds to the West of the Andes of Colombia Titulo en Español: Cruzando o desviando los Andes: un comentario sobre extensiones de distribución recientes de aves cis-Andinas al oeste de los Andes de Colombia.titulo en Portugues: Cruzando ou desviando os Andes: um comentário sobre extensões de distrubuição recentes de aves cis-Andinas ao oeste dos Andes da Colômbia.Resumen: Varias especies de aves cis-Andinas (i.e. Orinoco-Amazonas) han sido reportadas recientemente en la ver- tiente occidental de la Cordillera Oriental y el valle medio del Magdalena de Colombia (i.e. trans-Andes). En este artículo presentamos los registros adicionales para tres de estas especies. El Colibrí Llanero (Polytmus guainumbi), la Mirla Caripelada (Turdus nudigenis) y el Chango Llanero (Quiscalus lugubris). Reportamos por primera vez el Moriche Blanco (Cissopis leverianus) en la región trans-Andina. También discutimos algunas hipótesis que explicarían estos registros trans-Andinos con base en la ecología de estas especies y las caracte- rísticas del paisaje. Dada la acelerada tasa de pérdida de hábitat y fragmentación a lo largo de las laderas An- dinas y tierras bajas circundantes, en conjunto con el efecto del calentamiento global sobre los rangos de las especies, sugerimos que las expansiones a través y alrededor de los Andes podrían ser más comunes durante las próximas décadas. Las especies generalistas podrían liderar las expansiones, mientras que las especies especialistas podrían enfrentar reducciones poblacionales debido a sus limitadas habilidades de dispersión. Estos registros evidencian la necesidad de monitorear la transformación del paisaje, la colonización y viabili- dad de las poblaciones de aves, así como la necesidad de continuar el trabajo de campo, incluso en regiones consideradas relativamente bien muestreadas en el país.Palabras clave: Dispersión, extensión de distribución, levantamiento de los Andes, pasos de montaña, trans-Andino, transformación del paisaje.Abstract: Several cis-Andean (i.e. Orinoco-Amazon) bird species have been recently recorded on the west slope of the Cordillera Oriental and the middle Magdalena valley, in Colombia (i.e. trans-Andes). Here, we provide additional records for three of these species. White-tailed Goldenthroat (Polytmus guainumbi), Spectacled Thrush (Turdus nudigenis) and Carib Grackle (Quiscalus lugubris). We report Magpie Tanager (Cissopis leverianus) for the first time in the trans-Andean region. We also discuss some hypotheses explaining these trans-Andean records based on the ecology of these species and landscape characteristics. Given the accelerated rate of habitat loss and fragmentation along the Andean slopes and adjacent lowlands, coupled with the effect of global warming on species’ ranges, we suggest that cross- and bypass-Andean expansions could become more common in the next decades. Generalist species could lead those expansions, whereas specialist species could face population reductions due to their limited dispersal abilities. These records show the necessity of monitoring the dynamics between landscape transformation, colonization and population viability of birds, and continuing fieldwork, even in areas considered relatively well sampled in the country.Key words: Andean uplift, dispersal, landscape transformation, mountain passes, range extension, trans-Andean.Resumo: Várias espécies de aves cis-Andinas (ex. Orinoco-Amazonas) têm sido reportadas recentemente na vertente ocidental da cordilheira Oriental e o vale Meio do Magdalena, em Colômbia (ex. trans-Andes). Nesse artigo apresentamos registros adicionais para três dessas espécies. Beija-flor-de-bico-curvo (Polytmus guainumbi), Caraxué (Turdus nudigenis) e Iraúna-do-norte (Quiscalus lugubris).Reportamos pela primeira vez a Tietinga (Cissopis leverianus) na região trans-Andina. Também discutimos algumas hipóteses que explicariam esses re- gistros trans-Andinos com base na ecologia dessas espécies e características da paisagem. Devido à acelerada taxa de perda de habitat e fragmentação ao longo das encostas Andinas e terras baixas ao redor, em conjunto como efeito do aquecimento global sobre o território das espécies, sugerimos que as expansões através e ao redor dos Andes poderiam ser mais comuns durante as próximas décadas; As espécies generalistas liderar as expansões, enquanto que as espécies especialistas poderiam enfrentar reduções populacionais por causa de suas limitadas habilidades de dispersão. Esses registros mostram a necessidade de monitorar a transformação da paisagem, a colonização e a viabilidade das populações de aves, assim como continuar o trabalho de campo, incluso nas regiões consideradas relativamente bem amostradas no país.Palavras chaves: Dispersão, extensão de distribuição, levantamento dos Andes, passagem de montanha, trans- Andino, transformação da paisagem.

Highlights

The Eastern Cordillera (Cordillera Oriental) of Colombia have played a significant role in the biogeography of northwestern South America, by separating tropical lowland forests of the Amazonian basin from those of west of the Andes in Colombia and Central America (Chapman 1917; Haffer, 1967; Brumfield and Caparella 1996)
The occurrence of species with predominantly Amazonian distributions in the west of the Andes is often explained by four additive mechanisms operating at different time scales: (i) species could have been widely distributed in the whole northwestern South America before the final uplift of the Andes (Chapman 1917); (ii) dispersal over low passes in the northern Andes (Chapman, 1917); (iii) dispersal via corridors of tropical wet forest or grasslands around the northern tip of the Colombian Andes during the Quaternary (Haffer, 1967); and (iv) recent range extensions caused by deforestation, which facilitates expansion of non-forest dwelling species
The records brought here are into two classes: grassland-restricted species previously unrecorded west of the Andes or overlooked in museums (P. guainumbi), and open-country species (T. nudigenis, C. leverianus, and Q. lugubris) that have presumably expanded their distributions recently

Summary

Introduction

The Eastern Cordillera (Cordillera Oriental) of Colombia have played a significant role in the biogeography of northwestern South America, by separating tropical lowland forests of the Amazonian basin from those of west of the Andes in Colombia and Central America (Chapman 1917; Haffer, 1967; Brumfield and Caparella 1996). The occurrence of species with predominantly Amazonian distributions in the west of the Andes is often explained by four additive mechanisms operating at different time scales: (i) species could have been widely distributed in the whole northwestern South America before the final uplift of the Andes (Chapman 1917); (ii) dispersal over low passes in the northern Andes (Chapman, 1917); (iii) dispersal via corridors of tropical wet forest or grasslands around the northern tip of the Colombian Andes during the Quaternary (Haffer, 1967); and (iv) recent range extensions caused by deforestation, which facilitates expansion of non-forest dwelling species (i.e. grassland and/or open country species). Little discussion has been developed about the ecological and biogeographical implications of these range ex-

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Conclusion