Nepal’s government has recently adopted guidelines to make infrastructure such as roads, dams and railway lines wildlife-friendly, following pressure from conservationists and NGOs.
But not all wildlife have been included, with birds, especially those living in dense forests, likely to still be negatively impacted despite the mitigation measures.
The guidelines, issued in April, classify wildlife that could be impacted by infrastructure into five categories Small (such as tortoise, snakes and other reptiles and amphibians); small mammals (squirrels, rabbits, porcupines and civets); medium-sized animals (wild cats, dholes, hyenas and monkeys); big animals (rhinos, tigers, bears, deer and buffalo); and mega animals (wild elephants).
“Linear infrastructure such as roads and power lines severely impact birds, especially those that live in dense forests,” or forest specialist birds, said prominent Nepali ornithologist Hem Sagar Baral. “However, 90 out of 100 infrastructure projects in Nepal don’t take the potential impacts on birds into consideration,” he added.
“As tigers and rhinos get killed in collision with vehicular traffic, authorities tend to focus on these mega faunas when designing wildlife-friendly infrastructure,” Baral said. “Birds, who also suffer, mainly due to the fragmentation of their habitat, get little attention.”
Fragmentation of habitat is one of the key challenges facing forest birds in the region, according to a recent study conducted in the Mai Valley in eastern Nepal, designated by BirdLife International as an Important Bird and Biodiversity Area. The valley is home to birds such as the rufous-throated wren-babbler (Spelaeornis caudatus), the spiny babbler (Acanthoptila nipalensis), and the hoary-throated barwing (Sibia nipalensis).
Under the study, lead author Aastha Joshi and her team, including Baral, compared the diversity of birds found in two forests in the Mai Valley:
one contiguous (Hangetham Community Forest) and the other isolated (Maipokhari Religious Forest).
“We chose the Maipokhari forest habitat as a test case for isolated forests as the development of infrastructure around it caused the religious forest to be fragmented eventually and be surrounded by agriculture land,” Joshi said.
The Hangetham Community Forest, by contrast, developed as a contiguous forest within the Panchthar-Ilam corridor of Nepal, connecting forests of two different districts, thanks to the active participation of the community in its conservation.
Climatic conditions were assumed to be identical for both forests, which are just 20 kilometers (12 miles) apart, Joshi said.
The researchers recorded bird sightings in the two forests from December 2019 to January 2020, and then again in March 2020 and March 2021 (curtailed due to COVID-19 restrictions). They found that the contiguous forest supported a significantly higher bird diversity than the isolated forest.
“As the continuous forest is surrounded by forests, it offers a wide range of micro habitats, food sources, and nesting sites away from predators and competitors,” Baral said. When the forest habitat is fragmented, the specific requirements of these birds can’t be met, he added. That’s why measures such as building overpasses and underpasses and culverts don’t necessarily help mitigate the impacts of roads on birds, he said.
The team recorded a total of 1,138 individual birds belonging to 141 species throughout the entire study.
The overall result showed a higher number of species in the contiguous forest (116) compared to the isolated forest (84).