How Climate Change is affecting bird distribution and migration patterns in India 

By Vivek Saini

A recently published research has found that as many as 66 to 73% of the 1,091 bird species it studied to comprehend the effects of climate change were likely to move to higher elevations or northwards by 2070. The unprecedented effects of climate change on India’s biodiversity were highlighted in a paper titled “Projected Shifts in Bird Distribution in India under Climate Change” which was published in Diversity, a peer-reviewed, open-access journal. The work by researchers Arpit Deomurari, Ajay Sharma, Dipankar Ghose, and Randeep Singh demonstrates that the habitat of long-distance migratory birds is more susceptible to climate change.

Does climate change really affect biodiversity? 

The threat to natural ecosystems continues to rise as a result of the ongoing anthropogenic consequences of greenhouse gas emissions and the alteration of natural land areas. Ecosystems and biodiversity have been negatively impacted, frequently permanently and in a connected manner. Global mean temperatures are predicted by the IPCC to rise by 0.3 to 4.8 °C by the end of the twenty-first century, and according to a more recent forecast, they have risen by 0.8 °C over the previous 150 years. The distribution of species and community assemblages could be considerably impacted by this rate of climate change. Moreover, endemic species in biodiversity hotspots are predicted to suffer a doubled risk of extinction with 1.5 °C to 2 °C global warming and a more than tenfold increase with 3 °C global warming. 

Many studies have documented how warming of the climate has an impact on various creatures. The most significant consequences are:

• Changes in species distribution
• Reproduction and 
• Demography

Several species have reportedly evolved to resist the negative impacts of climate change by delaying or prolonging the timing of their reproductive cycles or by abandoning their current breeding territory and relocating to breeding locations that have a more suitable environment. As temperatures have risen in recent decades, the distribution of bird species in Eurasia and North America has migrated toward the poles and mountain peaks. Because of this, range shifts are now widely recognised as a sign of the observable effects of climate change on avian species and communities.

Biodiversity responses to global warming 

Natural habitats and species are being harmed in ways that are still unclear due to the climatic changes brought on by climate change. There are indications that climate change is impacting biodiversity, and pressure is being placed on species already in danger due to other human activities by changes in rainfall patterns, harsh weather, and ocean acidification. The threat that climate change poses to biodiversity is predicted to grow, yet healthy ecosystems also have the power to mitigate the effects of climate change.

By 2030, global temperatures may be 1.5°C (2.7°F) higher than they were before the industrial revolution, if current rates of warming continue. The severity and frequency of fires, storms, and droughts are increasing, significantly affecting biodiversity. The end of 2019 and the beginning of 2020 saw the destruction of 97,000 km2 of forest and adjacent habitats in Australia by severe fires now known to have been exacerbated by climate change. This increases the risk to biodiversity, which is already under attack from other human activities.

Bird distribution and climate change

The four researchers carried out the study to understand better how various climate change scenarios may affect the range and distribution of Indian birds as well as the impact on species richness.

Using maximum entropy-based species distribution algorithms, scientists created fine-tuned species distribution models to forecast how 1,091 terrestrial bird species would be dispersed in India by 2070 on two climatic surfaces (RCP 4.5 and 8.5). To illustrate various climate outcomes, the Intergovernmental Panel on Climate Change (IPCC) has selected Representative Concentration Pathways (RCPs). 

Lead researcher Deomurari, who is affiliated with the World Wild Fund for Nature-India, stated that their findings would influence national-scale conservation planning and management of birds in response to climate change as well as establish the conservation priorities in India going forward.

According to their study, migratory and partially migratory species are more affected by climate change when it comes to range decrease (62.88% and 68.01%, respectively, compared to 54.08% for sedentary species). 42 species were modeled from 78 indigenous species in India. By 2070, it’s anticipated that fewer climatically suitable locations would support about 75% of the world’s endemic bird species.

The researchers also studied how elevation affected species diversity. The turning point for all the species under investigation, they found, occurred between 2000 and 2500 meters, with diversity rising above and dropping below it.

The study demonstrated that the habitat of long-distance migratory birds is more susceptible to climate change. These birds’ migration patterns are closely correlated with climate. It is stated that migratory birds would most likely face a higher threat from climate change as their ranges are more likely to shift northward and get smaller. Although the ranges of about 22–27% of bird species may grow, if their new or expanded acceptable habitats are located outside of protected areas or in an area that is becoming more developed, they will still be at risk.

Deomurari said that the study’s findings led to the creation of brand-new, high-resolution maps of India’s terrestrial bird species richness. “We predict predominantly northward shifts in species ranges, similar to predictions made for avifauna in other regions, such as Europe and the USA” he added. 

Projection of species loss 

There are frequent inconsistencies and uncertainties with regard to future forecasts of the effects of climate change. It’s interesting how perceptions of the impact of climate change and predictions for the future frequently diverge sharply. Although it is not yet possible to establish that any bird species have gone extinct globally due to the climate, massive species losses are expected in the next few years. 

Of the 1091 species that were modeled, the study found that 66-73% of bird species in India will move to higher altitudes or move northward, and 58-59% of bird species (RCP 4.5 and 8.5) will lose some of their distribution ranges. In addition, distribution areas for 41-40% of bird species would expand. In areas above 2500 m in elevation, bird species diversity will dramatically increase under both RCP scenarios (RCP 4.5 and 8.5). By 2070, the species richness of the western Himalayas, Sikkim, northeast India, and western Ghats regions is predicted to have seen significant changes under both RCP scenarios.

Sutirtha Lahiri, PhD scholar from the University of Minnesota, USA, told CFC India, “This is an interesting study that models species distribution through time and projects that into the future to show that species are shifting northward, a trend that is seen globally. This underscores the need for India to focus heavily on verifying these modeled distributions by investing time, resources and capacity building across different entities (government, institutions, organizations) to conduct field-based studies of birds. Much of India’s birds are understudied because of logistical, financial and bureaucratic hurdles, and it is imperative to focus on long-term research of birds to verify these trends for actionable and relevant policymaking.”

It is to be expected that certain species will use ecological innovations to respond to these novel problems. Species under duress will be forced to adapt to new circumstances, particularly when there are changes in relative abundances within populations. When species that can quickly and effectively adapt to new conditions compete for resources, the more generalist or inventive (e.g., niche-switching) species may fill any openings that become available during competition with the species which are unable of quick and effective adaptation to the new conditions. Thus, climate change could have an impact on not just the competition between species but also the distribution of subspecies and genetic diversity.

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References:

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6. https://www.ipcc-data.org/guidelines/pages/glossary/glossary_r.html
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9. Image source:

https://www.oneindia.com/feature/explained-how-climate-change-is-affecting-breeding-of-birds-2923840.html