The key factors responsible for the decline are urbanisation, infrastructural development, environmental pollutants, and climate change. Here is a detailed look at some of these threats to birdlife in India, the extent of their severity, and how they affect birds.

Climate change

The average global temperature has risen by over 1 degree Celsius since pre-industrial times, resulting in catastrophic consequences not only for humans but also for other living beings, like birds.

Climate change affects bird reproduction and survival through the disruption of species interactions by phenological mismatches — it occurs when the timing of annual events like breeding, nesting and migration become out of sync.

“Mismatches in seasonal timing (of migration, breeding, emergence) between birds and their prey can reduce survival and reproduction and also lead to fatal competition with other species,” the report said.

Soaring temperatures force sedentary birds to go through rapid adaptive changes. For instance, Amazonian birds over 50 years lost body weight to lose heat more efficiently, the report said.

Moreover, sapping heat compels birds to change their behaviour. They tend to spend more time looking for shade instead of searching for food. This can have an adverse effect on their survival and reproduction.

Climate change leads to new and dangerous interactions between different species. A case in point is Hawaii, where with rising mercury, mosquitoes have colonised higher altitudes. This has given rise to malaria among mountain birds (Yes, humans aren’t the only ones who get malaria from mosquitoes).

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Urbanisation

The most urbanised regions in India have the least number of bird species, the least number of rare species, and the fewest insectivorous species, according to the report. It’s because urbanisation results in loss of natural habitat for birds and it exposes them to more air pollution and high temperatures.

Not only this, cities have noise pollution, which forces birds to “sing louder, or at different frequencies, or, in the worst case, to abandon otherwise suitable habitat,” the report noted. Meanwhile, light pollution may confuse and disorient them, causing them to collide with buildings. Ultimately, lack of food supplies in urban areas leads to the homogenisation of bird communities as only behaviourally dominant species such as House Crows and feral Rock Pigeons are able to survive.

Monocultures

Monoculture is the practice of growing one type of seed in a field at a time. In India, commercial monoculture plantations of rubber, coffee, and tea have been rapidly expanding in recent years. For example, tea plantations have grown from 5,214 sq km to 6,366 sq km from 2003 to 2020, the report said. Oil palm plantations have also increased across the country with expanding hotspots located in Andaman and Nicobar Islands, and the northeastern Himalaya.

However, such plantations are detrimental to the well-being of birds. The report mentioned: “Commercial monocultures are known to harbour fewer bird species than natural forests within the same biome.”

For instance, oil palm plantations in Mizoram support only 14% of the bird species found in comparable rainforests. In Uttarakhand, teak plantations can shelter just 50% of the total woodpecker species seen in the state’s sal forests.

Energy infrastructure

In the context of the looming climate crisis, countries have started to generate power using renewable resources instead of depending on conventional methods like coal-fired power plants. It has led to an increase of wind turbines in a country like India, where they have been installed in a wide range of landscapes including coastal areas, Western Ghats mountaintops, open arid lands, agricultural lands, and grasslands.

Although wind turbines are eco-friendly, they have emerged as a threat to birds, the report has revealed. A wide range of species are known to have been killed due to collisions with wind turbines. Several of them have migrated to regions where there aren’t such giant devices.

The report said the transmission lines have also led to the death of many large-bodies species because of collision and numerous small-bodies species have been electrocuted. “A literature review reveals that over 60 species from 33 families of birds are affected by collisions and electrocution at power lines in India,” it added.

Such incidents may cause a drop in population levels and a change in the migration patterns of birds.