Birds face barriers to relocation as climate change onslaught continues
Relentless climate change is forcing people worldwide to make adjustments to their lives. But how are the Earth's creatures, birds in particular, adapting to the environment's transformation? New research from the UK shows that natural barriers mean many African birds will struggle to adapt to the changing climate. The key findings are published in the Proceedings of the Royal Society B journal. Global warming will wreak havoc on birds' habitats, forcing them to move to more suitable areas. However, natural features of the landscape will restrict where they will be able to move, according to the researchers at Imperial College London in the UK. Furthermore, some land bird species will be obliged to move to new habitats. Some sub-Saharan species will be forced to live in areas that will become too hostile for their survival. According to the researchers, a perturbing discovery is the growing risk that these birds will not be able to move across areas that vary significantly from their familiar landscapes because they have not adapted to life across multiple habitats. 'As the climate changes and some habitats become inhospitable, bird species may start to move - stretching their ranges as they track the changing climate across the landscape, looking for new, agreeable habitats,' explained Lynsey McInnes of the Grantham Institute for Climate Change at Imperial College London. 'Our study suggests that these vital movements could run into difficulties if the birds' escape routes cross regions that they're not well adapted to survive in - such as mountain ranges, arid plains or tropical forests,' she added. 'These regions create barriers which many birds cannot cross because they do not provide the right kind of food and shelter.' In this study, the researchers evaluated digital maps of the current geographical ranges of almost 1,900 species of sub-Saharan land birds. The results are worrisome. Based on the data, a sizeable number of species' ranges end abruptly and these 'barriers' correspond with dramatic changes in Africa's terrain, vegetation and topography. Examples of the ranges of species - like the Violet-Tailed Sunbird and the Congo Serpent Eagle - end where the tropical rainforests of Central Africa meet the surrounding savannah, the researchers said. The ranges of other species, such as the Udzungwa Forest Partridge and the Usambara Eagle Owl, end on the slopes of the Eastern Arc Mountains of Kenya and Tanzania. 'We find strong, broad-scale patterns of impermeability across Afrotropical birds, despite the idiosyncrasies of survival, reproduction and immigration that inevitably define individual species' range limits,' the authors write. 'Of the variables assessed, measures of habitat variability (biome and landscape heterogeneity and elevational range) are the most consistent predictors of impermeability.' Said Dr David Orme of the Department of Life Sciences at Imperial College London: 'We hope to combine our data showing the locations of these 'barriers' with African climate projections, so we can predict species which may be most at risk of getting stuck if they try moving to escape climate change.' He added that if the researchers could identify the species that may face these natural barriers, 'conservationists may be able to help them across, perhaps through assisted migration programmes'. For his part, Professor Sir Brian Hoskins, Director of the Grantham Institute, commented: 'This study highlights the scope of the problems animals across the world are facing as the climate of their natural habitat changes.'
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