“An angelic land!” That’s how naturalist and wildlife photographer Sarangapani Neog describes the almost 21 square kilometre area of Hoollongapar Gibbon Sanctuary in Assam, commonly known as Gibbon Wildlife Sanctuary (GWLS). In this protected land of the Assam plains, alluvial semi-evergreen forest and its patches of wet evergreen woodland, he has recorded 280 butterfly species, a collection now forming the second edition of his soon-to-be-published book, Butterflies of Gibbon Wildlife Sanctuary.
Ready for a challenge? Click here to take our quiz and show off your knowledge!
In this interview with Mongabay India, Neog shares where his fascination with butterflies started, the evolving nature of lepidoptera studies, the ideal time to observe butterflies at GWLS, and butterfly tourism.
“Gibbon WLS is famously known for housing seven primate species, including the endangered western hoolock gibbon (Hoolock hoolock). But little known is its rich butterfly diversity. It is a haven for lepidopterists and butterfly enthusiasts, with easy-to-follow trails. The roadside vegetation and understorey habitats support many uncommon butterfly species,” Neog shared.
Notable sightings in the region include the Assam forest bob or brown forest bob (Scobura parawoolletti), Assam lancer (Isma bonota), red vein lancer (Pyroneura niasana), yellow vein lancer (Pyroneura margherita), several oakblue species (Arhopala spp.) such as the sylhet oakblue (Arhopala silhetensis) and falcate oakblue (Mahathala ameria), along with sailers (Neptis spp.), Archdukes (Lexias spp.), and barons (Euthalia spp.), he noted.
Ready for a challenge? Click here to take our quiz and show off your knowledge!
Where it all started
Neog’s fascination with butterflies began during weekend visits to his father, who has been serving as a forest guard at the Gibbon WLS for two decades. As a student, he would wander the forest trails with his camera. Later, he chose to document those for his graduation project in 2014–15.
Recalling his journey to his first book, Neog says butterflies were still a relatively new subject of fascination then, without any formal studies having been conducted on the Lepidoptera of the sanctuary. “I had bought The Book of Indian Butterflies by photographer Isaac Kehimkar and began spotting species in the sanctuary. I used to share my unidentified photos with him on Facebook for identification, and he encouraged me to publish my findings as a book and even reviewed them online every night. The first edition, edited entirely through these exchanges, documented 200 butterfly species in the sanctuary.”
But it’s time for an updated second edition, Neog noted. “In my first edition, there were a few lapses in identification. For example, I had recorded the long-branded blue crow, but due to uncertainties, it remained a doubtful entry in the book. Now, I prefer to mention it only by its genus and species rather than the common name, as the specimen I photographed in the gibbon sanctuary is still not conclusively identified.”
While stating that terms such as “endemic” or “rare” are often loosely used, he suggests using “uncommon” instead, as it better reflects species that are not frequently observed, including those locally rare. For the official status of species, he points to the IUCN Red List and the Wildlife (Protection) Amendment Act, 2022.
Frequent taxonomic updates
The study of lepidoptera, Neog points out, is relatively new, and taxonomic updates are frequent. “Scientific names of butterflies often change as researchers uncover new evidence about their identity and distribution. These updates usually come from detailed studies of genitalia dissection, comparison of specimens, historical records, and earlier naming conventions,” he explained.
He cited the example of a “very rare” butterfly found in Gibbon WLS. In the context of Northeast India, the species was long known as the brown forest bob (Scobura woolletti), a name originally associated with butterflies from Borneo and parts of Southeast Asia. However, in 2010, a detailed taxonomic study revealed that the butterflies recorded in the Northeast were different from their Southeast Asian counterparts. Researchers compared wing patterns, genitalia structures, and other morphological traits, finding consistent differences between the two populations. As a result, the Indian specimens were reclassified as a new species, Scobura parawoolletti (also referred to as Assam forest bob). The name “para,” meaning “alongside” or “closely related to,” reflects its similarity to S. woolletti while recognising it as a distinct species.
Similarly, the five-bar swordtail (Graphium antiphates), a swallowtail butterfly found in India, has two main subspecies- the Sahyadri five-bar swordtail (G. a. naira) in the Western Ghats and the Himalayan five-bar swordtail (G. a. nebulosus) in the Himalayas and Northeast India. Earlier, they were referred to as Alcibiades and Pompilius, but a 2019 study clarified that Alcibiades belongs to the Malay Peninsula, while Pompilius is another name for the original Antiphates. Scientists now use ‘naira’ and ‘nebulosus’ for the Indian subspecies.
While Neog has updated the nomenclature in line with current taxonomy, he emphasises that the real highlight of the book is its visual clarity. Each species is illustrated with detailed, annotated anatomical breakdowns that highlight minute distinguishing features. This visual approach, he notes, will be handy for identifying butterflies that often appear deceptively similar across species or subspecies.
The yellow sailer group is a good example. The Manipur yellow sailer (Neptis namba), small yellow sailer (Neptis miah), and yellowjack sailer (Lasippa viraja) all belong to the Neptis group, which is known for being taxonomically challenging due to their similar appearances. “They differ in tiny, distinguishing features that only trained lepidopterists might notice. Most books on butterflies gloss over such subtle details, which makes precise identification difficult. Having faced these challenges myself, I have explained the identification methods more thoroughly in my updated work.”
Neog stresses that understanding their behaviour is key for documentation. “I would plan visits in the early mornings and evenings. Every species has its patterns, and you need to know these to find them in the right place at the right time,” he explains. Being cold-blooded, butterflies bask in the morning sun to warm their bodies before becoming active. “That’s when you get the best photographs. Later in the day, they are swift and restless, and much harder to capture on camera.”
Another ideal time to observe butterflies is during mud-puddling, when they gather on moist soil, riverbanks, or puddles to extract vital salts and minerals. “Mud-puddling is most often seen in males, as they need minerals, especially sodium, for reproductive success, which they then pass on to females during mating. The kaleidoscope of hundreds of butterflies is a spectacular sight,” he adds.
Moreover, many species exhibit seasonal variation in their appearance, known as seasonal polyphenism, often referred to as “dry form” and “wet form.” Certain species, such as the medus brown (Orsotriaena medus) or the common cerulean (Jamides celeno), that might look vibrant in March-April may look dull in October-November. In Assam, the best time for butterfly watching is during the pre-monsoon months, from late February to June–July, when the forests come alive in a dazzling spectacle.
Butterflies are indicators of ecosystem health
“Butterflies tell us a lot about the ecosystem, they avoid polluted areas and serve as reliable indicators of forest health. The Gibbon WLS is essentially a forest island, surrounded by human habitations and tea plantations on almost all sides. Since 2015, I have recorded around 70 new species. Some butterflies I once saw regularly have become rare, while others are now more common,” observed Neog.
His 340-page book, divided into six butterfly families — Hesperiidae (skippers), Papilionidae (swallowtails and parnassians), Pieridae (whites and sulphurs), Lycaenidae (gossamer-wings), Riodinidae (metalmarks), and Nymphalidae (brush-footed butterflies) — provides information on the current conservation status of each documented species and the optimal time to observe it in the sanctuary.
The sanctuary has long been at a crossroads due to a railway track constructed in 1887, which split it into two. This fragmentation has adversely affected wildlife, particularly leading to interbreeding depression amongst the apes. “Railway workers regularly clear shrubs and plants along the tracks, including lantana, which is an important nectar source and shelter plant for butterflies. They also use herbicides/chemicals to clear the grass along. Several die due to habitat disturbance.”
Interestingly, the railway track has also created conditions that attract certain species. Some butterflies feed on unconventional nutrient sources such as rotting fruit, carrion, and even animal or human feces, waste that often accumulates along the tracks. The black raja (Charaxes solon) is one such species. Others frequently sighted near the railway line include clippers (Parthenos sylvia), and nawabs (Polyura spp.).
He opines that pesticide use in surrounding tea gardens has also adversely impacted the butterfly populations, with runoff seeping into the sanctuary, and suggested sealing or concretising the border drainage.
Butterflies draw tourists
Over the last decade, butterfly tourism has slowly grown in Gibbon WLS, drawing visitors from abroad in particular. While some states have dedicated butterfly tour guides, Assam still lacks such initiatives. Recently, however, two young men from a neighbouring village have begun training under him to become butterfly tour guides. Neog has been a resource person for workshops organised by educational institutions and eco-camps, where he delivers lectures on butterfly taxonomy and takes participants on field walks. “It is essential to understand butterfly anatomy and behaviour to identify and classify them into the six families found here. We start with the basics of identification in the classroom and then head out on trails inside the Gibbon Wildlife Sanctuary,” he said.
He envisions an information centre in every sanctuary and national park of the state, not only as a resource on butterflies but as a repository of data on all fauna. “Such centres could serve as libraries and research hubs,” he stated. “They would benefit conservationists and researchers, and also create opportunities for schools and colleges to hold outdoor classes. With access to data and guided field visits, students would gain first-hand knowledge beyond textbooks.” His book, he adds, could serve as a springboard for further studies on host plants and other aspects of butterfly ecology in Northeast India.
Neog says that Assam’s rich butterfly diversity deserves greater recognition. “Declaring a state butterfly would be an important step towards conservation.”
This article originally appeared on Mongabay. Read the original article here.