Species File: Exploring India’s biodiversity, one species at a time.

In the forests of northeast India, a series of whoops and hoots rises through the canopy in a melodious crescendo every morning — the unmistakable song of the western hoolock gibbon. Pairs often duet to mark their territory, reinforce pair bonds and communicate with their family members.

The western hoolock gibbon (Hoolock hoolock) is India’s only ape. While adult males have a fully black coat, females are buff to golden-brown. Exclusively arboreal, which means they spend their lives on trees, they use their long arms to swing between branches with ease. They feed primarily on fruits, and occasionally leaves and insects, making them vital for seed dispersal and forest regeneration.

In India, the species is found in the tropical and subtropical forests of the northeast, across Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland, and Tripura, with populations extending into Bangladesh, Myanmar, and perhaps southern Tibet. Two other hoolock gibbon species — the eastern hoolock gibbon (Hoolock leuconedys) and the Gaoligong hoolock gibbon (Hoolock tianxing) — are found in Myanmar and China.

An estimated 90% of the global hoolock gibbon population has been lost over the past three decades. Around 3,000 western hoolock gibbons are believed to remain; 2,600 of them in India. According to the IUCN Red List, the western hoolock gibbon is listed as endangered, as is the Gaoligong hoolock gibbon; the eastern hoolock gibbon is listed as vulnerable. The species receives the highest level of legal protection in India, under Schedule I of the Wildlife (Protection) Act, 1972.

Hoolock gibbons require contiguous, closed-canopy forests for survival, and are thus highly vulnerable to habitat loss and fragmentation. The loss of even a single connecting tree can render fragments unreachable. Hunting and the illegal pet trade compound the pressure.

In an earlier story published by Mongabay-India in 2019, primatologist Narayan Sharma, Cotton University, Assam, said: “When a contiguous habitat is reduced to scattered smaller fragments, they become ‘habitat islands’ in an inhospitable sea of degraded habitat. This could result in inbreeding. The resultant offspring are often weak, sometimes sterile or may have little reproductive fitness.”

Read more about the hoolock gibbon in our stories on saving India’s only ape, community conservation efforts, and how tree bridges could help connect fragments.

Banner image: A western hoolock gibbon in Namdapha Tiger Reserve. While adult males have a fully black coat, females are buff to golden-brown. Image by Rohit Naniwadekar via Wikimedia Commons (CC BY-SA 4.0).

Global biodiversity assessments have often suggested that the impacts of invasive alien species are greatest in wealthy countries of the Global North. A new study, however, challenges this notion and establishes that the severity of environmental impacts is generally higher in the Global South and calls out research bias for distorting the global picture.

The study, published recently in Science journal, combines two global datasets: GIDIAS, which contains more than 22,000 documented impacts involving over 3,300 invasive alien species from more than 6,700 scientific and grey-literature sources across 172 countries, and SInAS, which records the distribution of more than 39,700 alien species worldwide.

Considering research effort and the number of reports are much higher in the Global North, simply counting invasive species or documented impacts can make the region appear disproportionately affected. To better understand the impact, researchers, Sven Bacher, Petr Pyšek and Hanno Seebens used the IUCN’s Environmental Impact Classification for Alien Taxa (EICAT) under which an impact is considered severe when an invasive species causes a decline in a native population, local extirpation or global extinction.

Rather than simply counting how many invasive species or impacts have been recorded in a region, the researchers calculated average impact severity: the proportion of documented impacts that are severe. This was intended to reduce the effect of differences in research effort between countries.

The key findings include higher average impact severity in the Global South, the influence of research bias on assessments of invasive species impacts, the particular vulnerability of emerging economies, and the role of governance and management capacity in determining impact severity than large economies in the Global North.

The paper identifies India as one of the large, high-income developing economies where this pattern is visible. India has relatively high absolute numbers of documented impacts, but also a distinctly higher average impact severity than large economies in the Global North.

One of the biggest takeaways from the study is that weak governance and limited management capacity act as major drivers of high impact severity. Failure to recognise the Global South as facing the highest IAS impacts diverts attention away from the most threatened regions.

Previous research has identified emerging economies as countries likely to see the largest increases in alien species numbers in the near future as a result of strong economic development, potentially leading to more impacts, many of them severe. By contrast, wealthy countries of the Global North may have high introduction rates of alien species but also stronger governance and better management capacity as compared with the Global South, allowing them to implement policies and manage invasive species more effectively. The paper shows that good governance and effective management can reduce the impacts of biological invasions across most taxa and ecosystems.

Banner image: Invasive giant African snails spotted in Kerala. Image by Drajay1976 via Wikimedia Commons (CC BY-SA 3.0).

Species File: Exploring India’s biodiversity, one species at a time.

They sleep upside down and hunt for prey in the dark using sound waves — what can’t bats do? The only mammals capable of true flight, bats are remarkably adaptable, found on every continent except Antarctica. They offer critical ecosystem services by preying on insect populations, including agricultural pests and disease-carrying insects. For example, the critically endangered Kolar roundleaf bat (Hipposideros hypophyllus) that survives in a single cave in Karnataka is known to munch on 4,100 species of insects, including mosquitoes that transmit dengue and malaria.

India has roughly 135 species of bats — about 10% of global diversity — of which around 16 are endemic. The Western Ghats alone host at least 63 species, including the rare Wroughton’s free-tailed bat (Otomops wroughtoni). The Western Himalayas are home to 53 species of bats, including the East Asian free-tailed bat (Tadarida insignis), which until recently, was not recorded in India. Bats have also adapted to cities, roosting in old trees, under roofs, temple groves or heritage buildings.

The ecology of bats can vary surprisingly. The Indian flying fox (Pteropus giganteus), India’s largest bat with a wingspan of up to 1.5 metres, forages by sight and smell rather than echolocation. The palm-sized painted bat (Kerivoula picta), with its bright orange fur and black wings is vulnerable to the illegal wildlife trade.

Aside from insectivorous bats that control pests, India also hosts nectar- and fruit-feeding bats that pollinate flowers and disperse seeds, while their guano enriches soil with key nutrients.

Despite the many crucial roles played by them, bats remain among India’s least protected wildlife. Only six of the species found in India carry the highest legal protection under Schedule I of the Wildlife (Protection) Act. According to Bat Conservation International, of the 122 Indian bat species assessed by the IUCN, only 23% have stable populations, while the rest are declining.

Threats include habitat loss from deforestation and agricultural expansion, roost destruction in caves and old buildings, persecution linked to myths and fears of disease, and, increasingly, collisions with wind turbines.

In a story published by Mongabay-India in 2023, agroecologist Iqbal Bhalla, said: “There is no doubt that bats are incredibly important to agricultural landscapes. I hope that in the next few years we can get to a more definite answer as to exactly what their economic value is in Indian agriculture.”

Read more about bats in our stories on Meghalaya’s bat diversity, and Tamil Nadu’s bats being erased by urbanisation.

Banner image: An Indian flying fox perches on a banana tree. Image by Praveen P. via Flickr (CC BY-SA 2.0).

Heatwaves and lightning have officially been recognised as natural calamities eligible for relief under the State and National Disaster Response Funds, Union Minister of State in the Ministry of Home Affairs, Nityanand Rai, told Parliament on August 4.

The decision to notify heatwaves and lightning as disasters follows the recommendations of the 16th Finance Commission, which had recommended their inclusion “considering the increasing frequency and intensity of extreme weather events arising from climate change,” Rai said.

Rai also revealed that the total number of heatstroke cases since March 1, 2026 had reached 4,853, based on data from 51,000 National Heat-Related Illness and Death Surveillance reporting units. Telangana recorded the most number of cases (915), followed by West Bengal (733), Chhattisgarh (660), and Andhra Pradesh (540). Only 20 deaths were recorded over the same period, with the highest number – 11 deaths – reported from Maharashtra.

The SDRF and NDRF funds can be used for response, relief, recovery, and reconstruction purposes linked to the notified natural disasters. Long-term preparedness and capacity building activities, however, will have to be paid for from state and national disaster mitigation funds.

Experts have long called for the inclusion of heatwaves in the list of notified disasters so relief is systematically provided to vulnerable and exposed populations. Before the nationwide notification, only a handful of states had notified heatwaves as disasters within their own jurisdictions, such as Haryana, Odisha, Kerala, Telangana, and Tamil Nadu.

Lightning, on the other hand, is responsible for the largest number of deaths due to any disaster reported in India. Deaths due to lightning have consistently increased since 1975, data from the National Crime Records Bureau shows.

Other natural calamities notified by the central government include cyclone, drought, earthquake, fire, flood, tsunami, hailstorm, landslide, avalanches, cloudburst, pest attack, and frost and cold waves.

Banner image: A woman cools herself off with an ice pack during a heat wave in Banda, Uttar Pradesh. (AP Photo/Rajesh Kumar Singh)

Over 60 civil rights groups have condemned the detention of Assam-based environmental and Indigenous rights activist Pranab Doley under the National Security Act, calling it a clear “attempt to punish and vilify activists for exercising their constitutional right to protest.” Doley led protests against a five-star luxury resort proposed to be built within the Kaziranga National Park and Tiger Reserve, a UNESCO World Heritage site housing the world’s largest population of one-horned rhinoceros.

Doley was detained under the National Security Act (NSA) on July 30, one day after securing bail from a sessions court. The NSA provides for preventive detention to maintain public order. Rights groups have called it a way to “to continue his unjust incarceration.”

Apart from the revocation of the NSA, the groups have demanded an independent investigation into police excesses against protesters, the release of all activists associated with land struggles in Assam, and a full, transparent disclosure of land allotments and tourism projects proposed in the National Park.

The luxury hotel is being developed by a Hyatt-linked company, Juniper Hotels, on land leased to them by the Assam Tourism Development Corporation. The Hyatt Group has since distanced itself from the project. Indigenous tea tribes facing eviction have petitioned the Gauhati High Court alleging the land for the project was forcibly acquired from them.

“Governments cannot be permitted to convert dissent and disagreement over development policy into questions of national security. Adivasi and Indigenous communities asserting their rights over land and for protection of the environment and natural resources, are not enemies of the nation,” the statement by rights groups says.

Doley was arrested on July 12 for “masterminding” a demonstration against the project on June 28, and was accused of attacking police personnel. A sessions court granted him bail on July 29, finding no evidence of violence against police, and on the contrary observing that the notice for his arrest was served belatedly.

“In matters where ecological preservation intersects with indigenous survival, the standard apparatus of criminal law cannot be used to suppress local anxieties. True public order is achieved not by silencing the affected, but by listening to them,” the bail order said. The next day, the Assam government imposed the NSA on Doley, which allows an accused to be held without trial or formal charges for up to 12 months.

The NSA notice claims that Doley violated the Foreign Contribution (Regulation) Act (FCRA) by engaging in “suspicious foreign transactions.”

“The use of the NSA against Doley is part of a growing pattern of BJP governments weaponising extraordinary laws to silence dissent. Similar attempts have been witnessed in Uttar Pradesh, where the NSA was invoked against labour activists protesting against exploitative working conditions in Noida,” senior Congress leader and former union environment minister Jairam Ramesh said in a post on X.

Several environmental NGOs have faced FCRA cancellation or suspension for opposing development projects in recent years.

Banner image: A tiger crosses a road in Kaziranga NP. (AP Photo/Anupam Nath)

Species File: Exploring India’s biodiversity, one species at a time.

A recent survey has found evidence of a significant smooth coated-otter population in Mettur dam and Kaveri river stretches of Salem district in Tamil Nadu. Local fishers and residents reported the presence of more than 1,000 otters in the region.

Otters are semi-aqautic mammals found in rivers, wetlands, and mangroves. Their sleek bodies and webbed feet make them expert swimmers and efficient predators of fish and other aquatic animals, helping regulate prey populations and maintain ecosystem health. They also have whiskers that are sensitive.

Of the 13 global otter species, three are found in India. The smooth-coated otter (Lutrogale perspicillata) is the most widely distributed, found in all major river systems south of the Himalayas. The Asian small-clawed otter (Aonyx cinereus), the world’s smallest otter species, lives in high-elevation streams of the Western Ghats, the Himalayan foothills, and parts of Northeast India. The Eurasian otter (Lutra lutra) is more elusive and solitary than the other two, and is found in the Himalayas through to the northeast, as well as parts of the Western Ghats and central India.

Population estimates for otters in India are difficult to determine, given how little the species has been studied. According to the International Union for Conservation of Nature (IUCN), the smooth-coated otter is listed as vulnerable, based on ongoing population declines driven by habitat loss and hunting pressure. The Asian small-clawed otter is also listed as vulnerable, while the Eurasian otter is classified as near threatened. In India, all three otter species are protected under the Wildlife (Protection) Act, 1972.

Otters face multiple pressures, including river pollution, dam construction that alters river systems, and conflict with fisherfolk. The greatest threat, however, is poaching for fur and body parts.

In an earlier story that Mongabay-India published in 2024, Katrina Fernandez, director of Wild Otters Research and co-author of a 2016 TRAFFIC report, said, “The otters are relentlessly hunted for their body parts. In the 2000s, otter skins made up around 30 percent of the fur trade in India, of which China was the largest consumer.”

Read more about otters in our stories on filming an otter family on the Kaveri, community-based otter conservation in Maharasthra, and poaching pressures in the northeast.

Banner image: Smooth-coated otters. Image by Anirnoy via Wikimedia Commons (CC BY-SA 4.0).