(A) Hodgson’s frogmouth, (B) Gould’s shortwing, (C) Fire-tailed myzornis (Phub Dorji)

The fragile Himalayas and the balancing act!

Ugyen Penjor discusses their latest research, conducted with colleagues Sherub Sherub and Rinzin Jamtsho, which explores the effects of land-use change on the functional and phylogenetic diversity of Eastern Himalayan bird communities.

Envision the Himalayas – snow-clad mountains, jagged peaks, ruddy-cheeked people, and of course the ‘Abominable Snowman’ or The Yeti. But what is more exciting about the Himalayas is the biodiversity.

The Himalayas can be aptly called the cradle of life: there have been many new discoveries recently — surprisingly mammals, e.g., Myanmar snub-nose monkey (about a decade ago) and Tibetan and Yunnan woolly flying squirrels (in the last few years) — despite the human population burgeoning and natural areas shrinking. Isn’t it amazing?

Today, over 200 million people live in the Himalayan region and another billion depend on it. Human pressure is hurting natural resources, increasing the risk of species extinction and the loss of ecosystem services that are vital to human well-being. Maintaining a trade-off between human development and biodiversity loss is a global challenge and particularly urgent in the ecologically fragile Himalayas.

In our study, we use birds as indicator taxa of ecological changes and investigated the impacts of anthropogenic disturbance (e.g., settlement and agricultural land) on the eastern Himalayan bird communities. We established transect surveys along varying altitudinal gradients across Bhutan and conducted point count surveys on three separate occasions in 2019-2020.

Fieldwork (Sherub Sherub)
Fieldwork (Sherub Sherub)
Fieldwork (Sherub Sherub)

The human land use (i.e., agriculture and settlement) negatively affected the overall bird community occupancy. However, a very interesting but unconventional relationship was observed between human land use and community diversity. We found that the functional and phylogenetic diversity of bird communities were higher in agricultural land and settlement compared with the surrounding forest — This has not been reported previously from the eastern Himalayas! Such findings are not idiosyncratic of montane bird communities where nuances in land-use change along the altitudinal gradient add to the complexity.

(A) Hodgson’s frogmouth, (B) Gould’s shortwing, (C) Fire-tailed myzornis (Phub Dorji)
(A) Hodgson’s frogmouth, (B) Gould’s shortwing, (C) Fire-tailed myzornis (Phub Dorji)

The evidence that agriculture and settlement harboured diverse functional traits suggests the opportunity for a broad range of ecosystem services. Farmers in Bhutan are plagued by armyworm (Mythimna separata) larvae infestation annually. Armyworm larvae are voracious herbivores and inflict colossal damage to crops, especially the young and tender plants. In such cases, we could, of course, take a little help from our feathered friends by encouraging them to nest near crop fields by providing conducive environments or habitats (e.g., nesting sites and roost trees).

Management intervention that promotes insectivores might be particularly helpful because avian insectivores are natural predators of worms, and this obviates the need to use chemical fertilisers (win-win!). However, some granivores are farmers’ foes; but this too can be intervened, by, for example, encouraging raptors (or the so-called ‘birds of prey’) to nest at edge habitats. This would require planting trees that grow in height.

So, a natural problem has a natural solution. But we need to know when and where to intervene. We recommend the use of trait- and phylogeny-based approaches to gauge the impacts of land-use change on biodiversity and thus integrate functional and phylogenetic diversity assessments into the mainstream monitoring programmes. Our study suggests that anthropogenic environments perhaps harbour a relatively stable community and at a medium level of disturbance, it might be possible to conserve diverse functional traits and reap ecosystem benefits.

Read the full research article “Anthropogenic land-use change shapes bird diversity along the eastern Himalayan altitudinal gradient” in Journal of Applied Ecology.

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