Are invasive plants better at competing with species in places they invade than species in their native range? A paper investigated this using Erigeron canadensis, commonly known as Canadian horseweed, to find that plants from non-native populations had 19.2% higher competitive ability than those from native populations.

In the study, that advantage was evident across two watering conditions — watered and drought. Although drought reduced competitive ability overall by 12.9%, the difference between native and non-native populations was not significant.

Canadian horseweed is native to North and Central America that has spread widely across Europe, Asia and other regions. In some introduced areas, it can suppress other plant species and reduce local plant diversity.

The researchers conducted a large glasshouse experiment involving plants from 100 native and 165 non-native populations of Erigeron canadensis. They grew the plants under different conditions, including adequate water and drought, and tested how they performed when growing alone, alongside individuals of their own species, and alongside other plant species.

The paper suggests that the competitive advantage evolved independently in different regions. Genetic analyses identified four clusters, but increased competitive ability was evident in two. The result suggests that similar evolutionary changes can emerge independently rather than being explained solely by the spread of one already competitive lineage.

One of the crucial findings was that the advantage was associated with interactions with other species, rather than competition between individuals of the same species. Non-native plants showed 28.4% greater competitive tolerance and 38% greater competitive suppression under interspecific competition. These differences were not found under intraspecific competition. In other words, the advantage was specifically associated with competing against other plant species, not with competing against members of their own species.

The findings suggest that if non-native populations attain greater competitive ability, they may increasingly suppress other plants and contribute to reduced native plant diversity. The ecological impacts of an invasive species therefore may not remain constant after introduction.

The paper, however, cautions that it remains uncertain what drives the competitive ability and whether it is a general response because “the evidence is largely based on studies with limited sampling, inadequate consideration of population co-ancestry, and oversimplified estimates of competitive ability”.

Banner image: Canadian horseweed or Erigeron canadensis photographed in North America. Image by Aaron Volkening via Flickr (CC BY 2.0).

On October 11, the Upper Siang district administration issued an order prohibiting the assembly of five or more people amid intensifying protests against the Siang Upper Multipurpose Project (SUMP). The order was issued two days after four protesters were detained under the Arunachal Pradesh Unlawful Activities (Prevention) Act, 2014.

Protests against the 11,000 MW hydropower plant turned violent earlier this month after Chief Minister Pema Khandu’s visit to the district. Residents of the Siang, Upper Siang, and East Siang districts have consistently opposed the development of the dam, which will submerge 27 villages, including Upper Siang’s district headquarters, Yingkiong.

On October 13, three civil society groups — the Adi Banne Kebang United, Siang Indigenous Farmers Forum Youth Wing, and SUMP Affected Area Youth Association (SAAYA) submitted a memorandum to the Upper Siang District Collector condemning police atrocities and demanding the immediate release of those arrested for protesting. Police allegedly lathi charged protesters on October 4, days after protesters set fire to vehicles and stormed an MLA’s house.

The memorandum demands the unconditional release of protesters from police custody, the “immediate and complete withdrawal of Central Armed Police Forces from Siang and Upper Siang,” a halt on all studies being done to determine the dam’s viability in the area, and the quashing of all legal proceedings against protesters.

“Failure to comply will compel the youth and public to escalate democratic agitation, for which the district administration and law enforcement authorities shall be held solely responsible,” says the memorandum, seen by Mongabay-India.

“We’ve been approached by the authorities seeking advice on how to restore peace to the area. By the steps they’re taking now, like detaining people, can peace be restored?” asked Goto Apang, convenor of SAAYA, over the phone.

Ashok Tajo, Upper Siang’s District Collector, said that the area was peaceful. “The detainees will have to submit their representations to the state government challenging the detention order of the District Magistrate for release from detention.”

The imposition of UAPA on protesters, as well as curbs on public assembly, follow allegations of the movement being foreign funded. Bhanu Tatak, legal advisor to the SIFF, was served a notice by the Central Bureau of Information for allegedly violating the Foreign Contribution (Regulation) Act. The notice alleged Tatak had received ₹17 lakh (₹1.7 million) without registration under the FCRA.

The protests oppose the attempt to carry out a Pre-Feasibility Report (PFR) study by the NHPC, which is developing the project, to determine if the locations of the proposed dam are viable. The PFR is one of the few pending studies left before completing the dam’s detailed project report.

Banner image: Protests against the SUMP held in Upper Siang in 2024. Representative image by special arrangement.

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

During the monsoon this year, sloth bears seemed to quite literally unearth an unusual prey in the forest floor of Amrabad Tiger Reserve, Telangana: shield-tailed snakes. Researchers studying over a hundred scat samples found the remains of the snake in a handful – potentially the first record of the bears hunting the snake.

The shaggy-coated and long-clawed sloth bear (Melursus ursinus) is a mostly nocturnal mammal that is native to the Indian subcontinent. It has a long, flexible snout and mobile lips that enable it to suck up ants and termites. While they love their occasional meat tidbits, they mostly thrive on insects, fruits and wild berries.

Sloth bears usually live in rugged terrain with rocky hillocks and dense scrub vegetation. Like other bears, they depend on dens as safe spaces for resting and raising their cubs. They can adapt to life in a wide range of habitats such as dry grasslands, scrublands, and moist tropical forests. The only population estimation of sloth bears in India stems from a 2006 survey: between 6,000 to 11,000 sloth bears, with around half of them living outside protected areas.

The IUCN Red List classifies the species as vulnerable, which means it faces a high risk of extinction in the wild. In India, it receives the highest legal protection under Schedule I of the Wildlife (Protection) Act, 1972.

Sloth bears may be helping regenerate forests by dispersing viable seeds. A study from Rajasthan’s Aravalli hills has found that their role as seed dispersers may help shape dry deciduous forests and influence plant regeneration.

Habitat loss and fragmentation are major threats to the sloth bear. Additionally, forest degradation hampers bear migration to colonise other forest patches. Poaching and local extinctions remain a concern, while their body parts are trafficked internationally as part of the illegal wildlife trade.

In a story published by Mongabay-India in March 2026, Nishith Dharaiya, director at the Center of Excellence for Wildlife and Conservation Studies, said, “Rocky hillocks and natural caves can function as important refuges for sloth bears even outside protected areas. It shows that suitable microhabitats may be more important for denning than the formal protection status of the landscape.”

Read more about a proposed sloth bear reserve caught between courts and a thermal power project, and struggles of the species in human-dominated areas.

Banner image: A sloth bear in Daroji Sloth Bear Sanctuary. Image by Bikash Das via Flickr (CC BY 2.0).

A new paper documents the first known record of a moth using the umbilicate lichen, Lasallia pertusa, as a camouflage background. Published in the journal Arthropod-Plant Interactions, the observation was made in July 2025 at Duggi, in Kugti Wildlife Sanctuary, Chamba district, Himachal Pradesh, at about 3,200 m elevation.

Lichen-associated camouflage has been documented before, including in moths. In this case, however, the association involves an umbilicate (attached to its substrate only at a single point), foliose (with flat, leaf-like lobes) lichen, rather than the more commonly documented crustose or bark-growing lichens. The finding, therefore, expands the range of lichen growth forms known to potentially participate in insect camouflage. It also points to the fact that a seemingly inconspicuous lichen can be an important part of an animal’s visual environment and survival strategy.

One of the authors, Sanjay Kumar Uniyal, informs Mongabay-India that though there have been similar observations of moths mimicking lichens in the past, this particular lichen species has been documented for the first time. “This might have an evolutionary consequence which can only be understood through further studies,” Unniyal shares.

L. pertusa has a large, perforated and highly irregular thallus (vegetative body), providing a particularly complex visual background, reports the paper. The moth that belongs to the family Noctuidae, was found resting directly on the lichen growing on exposed rock. The moth’s identification was based on photographs and expert examination. The paper reports that the moth species couldn’t be identified due to the absence of a specimen.

The proposed mechanism, however, is crypsis or background matching, one of the most widespread camouflage strategies among insects inhabiting visually heterogeneous environments, says the report. In this case, the moth resembles the visual characteristics of its immediate surroundings, reducing its contrast against the background.

The likely predators are visually hunting animals, particularly birds and lizards, although the study did not experimentally test whether those predators actually found the moth harder to detect.

The findings, however, come with an important caveat that it was simply an observation and not an experimental demonstration of camouflage effectiveness.

Banner image: A moth camouflaged against L. pertusa lichen. Image by Sanjay Kumar Unniyal.

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

Conservation efforts have re-established the greater one-horned rhinoceros in Assam’s Manas National Park. The species had once been wiped out from the park but was brought back through wild-to-wild translocation and rhino rehabilitation programmes. A recent study of the re-established population offers encouraging signs of adaptation in its restored habitat.

The greater one-horned rhino (Rhinoceros unicornis) is the largest of the three rhino species found in Asia. It is identified by a single black horn, about 8-25 inches long, and grey-brown hide with skin folds that give it an armour-plated appearance. It’s about half the weight of an elephant, going up to 2,700 kilograms and is around 6.5 feet tall.

Despite its size, the rhino is a good swimmer and spends considerable time in wetlands and grasslands. It mainly feeds on grasses, leaves, branches of shrubs and trees, fruit, and aquatic plants. The greater one-horned rhino now numbers at around 4,075 individuals found only in the grasslands of India and Nepal.

The IUCN Red List classifies the species as vulnerable, which means it faces a high risk of extinction in the wild. In India, it receives the highest legal protection under Schedule I of the Wildlife (Protection) Act, 1972, and is listed in Appendix I of CITES, which bans international trade.

Rhinos play an important role in shaping grassland and wetland ecosystems. However, habitat loss and fragmentation, invasive species and human-animal conflict remain major threats to the species. The rhino has also faced illegal hunting for its horns.

In a story published by Mongabay-India in April 2026, Mudit Gupta, Landscape Lead, Eastern Terai, Terai Arc Landscape, WWF-India, said, “Poaching remains a potential threat once rhinos are outside fenced protection, and it is countered by increased ground patrols, intelligence-led protection initiatives, ongoing radiotelemetry tracking of released rhinos, and close cooperation with enforcement agencies across borders.”

Read more about saving India’s wild ‘unicorns’ and what the DNA says about the future of rhinos in India.

Banner image: One-horned rhino with baby in Kaziranga National Park, Assam. Image by Joli via Wikimedia Commons (CC BY-SA 4.0).

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

Flying thousands of kilometres circumventing the mighty Himalayas, harriers arrive in India’s grasslands around July every year, when winter sets in across their breeding grounds in Central Asia and Russia. Mated pairs perform a suave mid-air food pass, with the male dropping prey for the female to catch during flight.

They hunt by the day, circling low and in zigzag patterns to find small mammals, birds, reptiles, and insects. In addition to controlling their prey populations, a recent study found that two harrier species — the pallid and Montagu’s harriers — are surprisingly also grassland gardeners; they consume seeds carried inside their prey’s gut and later expel them unharmed.

Of the 16 harrier species found worldwide, six visit India — Montagu’s, pallid, hen, pied, and the Eurasian (western) and eastern marsh harriers. Unusually for raptors, they nest on the ground, and roost communally in large numbers with other harrier species — the world’s largest such roost documented so far was at Velavadar National Park, Gujarat.

Most harrier species are listed as least concern by the IUCN, except the pallid harrier, which is near threatened due to a global population decline. In India, harriers receive the highest legal protection under Schedule I of the Wildlife (Protection) Act, 1972.

Long-term monitoring by Ashoka Trust for Research in Ecology and the Environment’s Harrier Watch programme found that the number of harriers roosting together had declined between 1985 and 2015, driven largely by the loss of grasslands to agriculture, livestock overgrazing, wind and solar plants, and invasive species. The decline in prey such as grasshoppers due to pesticide use also adds to the pressure.

In a story published by Mongabay-India in July 2026, Vishwatej Pawar, co-founder of The Grasslands Trust said, “Grassland specialist species like the harriers actually play an important role in stabilising the populations of insects, pests, and even rodents, which helps farmers. When their habitats change, either due to afforestation or due to trenches, they compete for space or are unable to nest, roost, or properly forage, which causes population decline.”

Read more about the harriers’ role in grassland seed dispersal, their extraordinary migration journey, and declining populations.

Banner image: A gliding hen harrier. Image by Larisa Artemyeva via iNaturalist (Public Domain).