Soaring through the Indian Himalayas: A Glimpse at High Elevation Birds
In the Indian state of Uttarakhand, nestled at the base of the Himalayas and surrounded by snow-clad mountains, is the breathtaking Chamoli district. Alpine forests and crisscrossing rivers form the landscape throughout Chamoli, providing a home to an abundance of flora and diverse wildlife, from the common Langur monkey to the elusive Leopard. The biodiversity in the Chamoli district is strongly shaped by its stratification across different elevations from sea level, with animals adapting within specific altitudes. This is especially true for Himalayan birds. We spoke to ecologist Sahas Barve, who conducted his PhD in Ecology and Evolutionary biology at Cornell University to further understand such altitude-specific adaptations. Over four years, Sahas travelled to Chamoli, each time immersing himself with the Himalayas, to study the ecological interaction between closely related bird species. In this article, we delve into the nature of Sahas' research and his experience in working in the remote mountains.
Himalayan Mountains. Photo by Shailee Shah
From his home in Ithaca, NY, Sahas boards a series of planes that shuttle him above the North Atlantic Ocean to Delhi, India. From there, a series of long and arduous bus rides on twisting mountain roads to the Himalayas await; his destination, Chamoli. Here, the buildings are nestled among hills adjacent to the impressive Alaknanda river with views of snow-capped peaks. Sahas is with his team made up of research students and scientists, and in the Chamoli village, they stay in family homes as guests of the Chamoli locals. Here, they are surrounded by temperate forests with a similar composition to those of Europe: Oak, Maple, Cedar, Spruce, and Pine.
"If a botanist from Germany walks into the Himalayan forests, they'd be able to identify most trees to the genus!"
As the elevation increases, Sahas explains that the community of flora changes: where at lower elevations tall trees are abundant, higher elevations contain alpine meadows with stunted trees that may only reach as high as your chest. As the elevation increases, the landscape transitions into windy grasslands. Critical for Sahas and his team, throughout these elevator deviations, Himalayan birds are ubiquitous.
"As you transition through elevations, you not only transition through habitats but also through a completely different set of species."
Uttarakhand, India. Photo by Amit Asthana on Unsplash
It took Sahas some time to begin appreciating the beauty of his surroundings and the abundance of biodiversity. He explains that prior to his PhD expedition, he was in Chamoli for a fast-paced and exhausting study. Sahas suggests that the type of field-work is not for everyone as the constant trekking through different elevations left little time for rest. However, this changed in his PhD research, and with new eyes, Sahas is reminded of the beauty the Chamoli district offers.
The workday begins at 3am, in the Chamoli village. Donning field-work gear, Sahas and the team start by raising mist nets in various locations across a five hundred meter diameter. The large nets are designed to appear as a light mist, making them almost undetectable and ideal for capturing birds required for their studies. Once the mist nets are ready and the sun begins to appear, the team awaits patiently for the birds to be caught. Throughout the day, the team must constantly check the nets until they are disassembled at sunset. This minimises the time the birds spend captured and, in turn, their potential distress. Upon being captured, the birds spend up to five minutes in the hands of the researchers. In that time, a blood sample is drawn for haemoglobin measurements, and a metal tag is attached to help identify the birds and report their capture location.
Uttarakhand, India. Photo by Shailee Shah
Sahas reveals that his research focused on two topics: how haemoglobin concentration varies across species, and the elevational distribution of bird species in the Himalayas and their tendency to compete with other species for space within overlapping elevation zones. Haemoglobin concentration reveals the hypoxic (low-oxygen) physiology of various bird species throughout the different elevations. This is of particular interest as the data tells the researcher how much time the birds can tolerate hypoxic conditions and how this differs between species.
"We saw that birds that spend most of their time at high elevation have a different hypoxic physiology than birds that move between elevations, between winter and summer"
Sahas explains that birds typically exist inside elevational zones shaped by ecological and environmental factors; however, the underlying mechanisms establishing these zones remain unclear. To observe this phenomenon, Sahas directed his research towards two bird species: the high-elevation green-backed tits Parus monticolus and the low-elevation cinereous tits Parus cinereous.
Photo by Łukasz Rawa on Unsplash
Numerous factors may contribute to defining the elevation zones in the Parus monticolus and Parus cinereous, including seasonal temperature changes and human-induced habitat changes. In response, the birds may utilise multiple strategies, such as increasing insulated plumage and shifting their elevation. An example of this can be seen when resource availability fluctuates, such as when food is scarce during the winter. To compensate for this, Sahas believes that the two bird species may compete within the overlap of their respective zones to expand their own territory and thus their access to resources. This is where mist nets play their part: upon capturing the birds Sahas and his team can identify the species of each subject and catalogue their capture location. The data is subsequently correlated with the different elevation zones, allowing Sahas to understand where the birds spend most of their time and if there are ultimately any changes to these.
Uttarakhand, India. Photo by Shailee Shah
The region is exceptional as it spans a significant elevation gradient of natural wilderness that is largely untouched by humans. This not only makes for an impressive research location but allows Sahas and his team to study the birds in an undisturbed environment. He explains, "There are very few places in the Himalayas that have a completely unbroken natural habitat from really low elevations to really high elevations, as generally there are villages". A significant outcome of this uninterrupted wilderness is that the region is teeming with wildlife. Sahas describes, "The field site is a really great place to see mountain ungulates called a Himalayan tahr. We've heard and seen signs of leopards several times and have seen big deer, called sambar, which are similar to red deer. We've been chased by black bears! There are high elevation monkeys called langur monkeys that go all the way up to almost 3500m. They're one of the highest living primates in the world, other than humans. There is a lot of wildlife!"
Over his four years spent at Chamoli, Sahas has successfully shown the tendency for birds to compete for elevational space. Whether it be for food or as a response to changes in climate. He has demonstrated the importance of preserving the natural environment in the Himalayas and how it can positively affect the region's biodiversity. Along with that success came a strong sense of personal growth and experiences that Sahas will take with him as he continues his scientific career.