Trashi Yangtse Nature-Bhutan

01/10/2026

Nature's Costumes: Mimicry

Look closely at this photograph. Who is looking back at you?

This morning, a green caterpillar was found in our flower garden at Trashi Yangtse Primary School. Those two big eyes are not eyes at all. They are false eyespots on its swollen front end. Its real head is small and tucked away underneath.

The big idea for everyone

Mimicry happens when a living thing looks, sounds, smells or behaves like something else, and that gives it an advantage, most often safety from a predator. Scientists name three players. The model is the thing being copied. The mimic is the copier. The receiver is the animal that gets fooled, such as a bird.

Our caterpillar uses two tricks in one body, and that is what makes it a fine teacher.

Trick 1: Resting
What it does: Stays still on a leaf, green and speckled.
What a bird may see: Nothing worth eating, just a leaf.
Name of the idea: Camouflage (hiding)

Trick 2: Disturbed
What it does: Tucks in its small real head and swells the front of its body.
What a bird may see: A pair of big eyes, maybe a small snake, maybe something too risky to attack.
Name of the idea: Startle display with false eyespots (surprising, and possibly copying a snake)

Scientists call this kind of disguise mimicry when an animal copies something else to stay safe. The hawkmoth caterpillar shows how nature builds costumes for survival.

Our Grade 6 students had a mini-lesson on it this afternoon, and their faces said it all.

Now your turn. Look at the second photo. Where do you think the horn is, and what is it for? Tell us in the comments.

Remember: look, do not touch. Leave every creature where you found it.
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The science behind the costume

Mimicry is evolution by natural selection made visible. In any population of caterpillars, some have slightly bigger or rounder eyespots. If predators hesitate more at those individuals, they survive more often and pass the trait on. Over many generations the display sharpens. No caterpillar decides to look like anything.

•Bates and Müller. Henry Walter Bates described harmless species copying harmful ones from his Amazon collections (1862). Fritz Müller later explained why harmful species benefit from sharing one warning pattern (1879).

•Frequency matters. Batesian mimicry works best when mimics are rarer than their models. If harmless mimics become common, predators learn that the pattern is safe and the protection fades.

•Three players, one signal. Model, mimic and receiver all shape the outcome. Receivers that learn quickly or see poorly change which mimics survive.

•Not all mimicry defends. In aggressive mimicry a predator copies a harmless signal. Some firefly females imitate the flash patterns of other species to lure males and eat them.

•Costs exist. A startle display takes energy and can expose the animal. Natural selection keeps it only because the benefits outweigh the costs.

TRASHI YANGTSE NATURE CLUB | LEARNING PACK

29/09/2026

This is a place where you can travel to break away from routine, test your assumptions, and discover who you are outside your normal surroundings.

Trashiyangtse lies at the ragged eastern seam of Bhutan, where the road peters out and the country thins into borderland, a place that feels less arrived at than stumbled upon after too many hours in a rattling bus. It is a district of stubborn traditions and quiet crafts, woodturners bent over lathes, papermakers beating Daphne bark into sheets, monks circling the Chorten Kora as if the world beyond the valley were a rumour, where time seems to have been mislaid and no one is in much hurry to find it.

Beyond the town the land folds into Bumdeling’s wetlands and alpine meadows of Pemaling, wintering ground for black‑necked cranes and a landscape that suggests not an end of the map but a margin where maps grow unreliable.

Photographs: Image 1: Pemaling Ney near Me La in summer with Rhododendron blossoms by Tandin Wangdi

Image 2 and 3: Aerial shots of Yangtse by Tshengyel's Studio

28/09/2026

Photographs: Phu Nyongla (Wylie: sNyong La) in the north of Trashiyangtse District

Phu Nyongla (Wylie: sNyong La), a peak in the north of Trashiyangtse district, is regarded as the abode of a btsan or yul lha (Wylie transliteration), a category of mountain deity venerated across Bhutan (Pommaret, 1996). This deity holds considerable significance in the lives of communities in the upper Kholong Chu Valley, particularly in the Bumdeling valley. The people of Bumdeling hold that Ap Nyongla, the tutelary mountain deity, resides on the summit and must be propitiated by the human inhabitants at regular intervals to secure his continued favour.

Huber (2020, 319) records that sNyong La lHa-btsan dKar-po is locally classified as both a btsan and a phu, and that the snow peak north of the sPang La pass is described as his "palace" (pho brang). As the original place-owner of the now-abandoned Tsango settlement, he remains the territorial deity of its migrant descendants, including those at Khomakang, Dingchung, and Longkhar in Bumdeling. During the Lhamoche festival, the peak serves as one of several temporary resting places for the Srid-pa'i lha, and the deity acts as host and as "chamberlain" (gzim dpon) to the sky deity Gurzhe, receiving offerings on his behalf. Informants treat offerings to sNyong La as equivalent to offerings to Gurzhe, just as a king is served through his minister, a relationship that also helps explain the sacrifice of domestic animals during the festival. Other beings are drawn into the same hierarchy: the btsan dBang-'dus rDo-rje Changchen, whose abode is a peak further up the valley, is co-opted as Gurzhe's acting "steward" (gnyer pa), and nine minor deities near Dingchung are recruited as his "cooks" (gsol dpon). The ritual specialist likened this arrangement to a royal court, with Gurzhe as king, the two btsan as his ministers, and himself as chamberlain.

Similarly, Ugyen Dorji, 76 years old from Bumdeling gewog, states, "Nango Azhi is propitiated by Zhapangpa and Beytsamangpa. Even by Khawlangpa. Then there is Shawang Lhapzang Karpo in Womanang. These are tsan or yul lha in the regions. There are others. It's in Serkem pecha. (Personal communication, September 28, 2026)"

References and Further Reading:

Huber, T. (2020). Source of life: Revitalisation rites and bon shamans in Bhutan and the Eastern Himalayas (Vol. 1). Austrian Academy of Sciences Press.

Pommaret, F. (1996). On local and mountain deities in Bhutan. In A.-M. Blondeau & E. Steinkellner (Eds.), Reflections of the mountain: Essays on the history and social meaning of the mountain cult in Tibet and the Himalaya (pp. 39-56). Verlag der Österreichischen Akademie der Wissenschaften.

Photographs and Text: Tandin Wangdi / September 2026

27/09/2026

WLB - Wiki Loves Butterfly in far east — Trashiyangtse, Bhutan

24/09/2026

Autumn in Yangtse

This can be literally the scenes and observations from your windows here and reading ''Song for Autumn'' by Mary Oliver. Her poem reframes the arrival of cold weather and decay not as a loss, but as a cozy, welcoming return to rest.

Song For Autumn
Mary Oliver

In the deep fall
don’t you imagine the leaves think how
comfortable it will be to touch
the earth instead of the
nothingness of air and the endless
freshets of wind? And don’t you think
the trees themselves, especially those with mossy,
warm caves, begin to think

of the birds that will come – six, a dozen – to sleep
inside their bodies? And don’t you hear
the goldenrod whispering goodbye,
the everlasting being crowned with the first
tuffets of snow? The pond
vanishes, and the white field over which
the fox runs so quickly brings out
its blue shadows. And the wind pumps its
bellows. And at evening especially,
the piled firewood shifts a little,
longing to be on its way.

© 2017 by Mary Oliver from Devotions, Pg. 152.

Photographs: Tandin Wangdi

20/09/2026

Field note: Trashi Yangtse Nature Club
Bhutan Glory, Bhutanitis lidderdalii: 4, 5 and 19 September 2026

What we saw

My daughter Sangay and I went out three times this September, on the 4th, 5th and 19th, to look for the Bhutan Glory. Each time we saw them in their natural habitat. Most were in flight, and some came down to feed on flowers, among them Swertia paniculata.

Our September 19 trip was more special because we guided Dr. Monsoon Jyoti Gogoi and his group including Pradeep Nayak, Dr. Sourabh Biswas, Dr. Rudra Prasad Das, Kamal Azad, and others.

The literature describes a butterfly that drifts high among the tree-tops and is found more often on ridges than in valleys. Its greyish underside makes it inconspicuous in the canopy shade. At rest it spreads its wings, and the forewings mostly cover the bright tricolored patches on the hindwings.

The timing fits what is known. In western Bhutan, males emerge at the end of August and are abundant by September, when the females begin to appear. Same is true in the east. Egg-laying may start in late September. The species has a single brood, confined to autumn. If that pattern holds here, our three visits fell in the best weeks of the year. The caterpillars feed on Aristolochia, so the butterfly depends on the forest that carries its host vines and nectar flowers.

How it came to science

Afterwards I went back to the beginning of the story. William Stephen Atkinson described the butterfly in the Proceedings of the Zoological Society of London in 1873. He wrote:

This fine insect was first discovered in May 1868, near Buxa, in the Bhutan Himalayas, at an elevation of 5000 feet, by Dr R. Lidderdale, of the Bengal Army. Dr Lidderdale obtained two specimens from the same locality in 1872; and from one of these, kindly communicated to me, the foregoing description and the accompanying drawing have been prepared.

I am glad to associate Dr Lidderdale's name with this very interesting discovery, which adds a new and remarkable form to the family of Papilionidae.

Other specimens have since been taken by Lt H.M. Rose of the Bengal Staff Corps.

— W.S. Atkinson, M.A., F.L.S., &c.

The whole description rests on one specimen and one drawing. The butterfly has kept its discoverer's name ever since, and it is still a remarkable form.
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George Talbot, in The Fauna of British India, Including Ceylon and Burma (1939), adds some detail on what it took to get more:

[Bhutanitis] lidderdalei was first discovered by Dr. Lidderdale in 1868 in Bhutan, at about 6,000 feet, near Buxa. Between 1886 and 1890 the late H. J. Elwes sent three parties of native collectors from Darjeeling to procure the insect. The first was plundered by the Bhotias, the second was attacked by fever and one of its members died, the third had a man killed by a tiger, and all returned unsuccessful. Specimens were later procured by Mr. A. V. Knyvett, then Inspector of Police, who gave them to Mr. Elwes …
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The two accounts disagree slightly. Atkinson gives 5,000 feet and Talbot about 6,000, roughly 1,500 m and 1,800 m. Talbot also spells the name lidderdalei. Both elevations sit inside the range the IUCN gives today, about 1,500 to 2,750 m, and up to 3,000 m in Bhutan. The butterfly has stayed where Lidderdale found it.

Set beside those collectors, our three outings were easy. Elwes's parties were robbed, fevered and killed, and all three came back empty-handed. Sangay and I walked out on a September day and saw many.

Why it was hard to get, and why it matters

The IUCN notes that the species' inaccessibility has resulted in high prices. It is listed under CITES Appendix II and is traded for ornamental, scientific and museum purposes. The Thai subspecies, ocellatomaculata, was intensively collected after its discovery in 1975. It is now considered possibly extinct there, from forest fires and over-collection. A butterfly that once cost lives to collect is also one that collecting can push toward extinction.

Status, as I read it

The IUCN assessed the species as Least Concern in 2020, on the strength of a huge range of over two million square kilometres. It also says the global population trend is unknown. It was once thought very rare and local in Bhutan, but has since been recorded from many places between 1,500 and 3,000 m. Its true status here still needs validating. It is considered Near Threatened nationally and is protected by law in India. In 1985 Collins and Morris rated it "insufficiently known" and asked for more information, and that request still stands.

One paper I read, on a newly found habitat in Yunnan, calls the butterfly endangered. I have followed the IUCN assessment, but the disagreement shows how thin the data are. That study also found the species locally abundant, with preferred host plants under 38 cm tall, growing only in broadleaf forest with abundant nectar plants. It suggests that conservation should focus on patches of broadleaf forest inside temperate pine forest.

Habitat loss is the threat that concerns me most here. The IUCN is careful to say the impact on this species is unknown. That is why records matter.

Trashigang is regarded as Bhutan's most famous place to watch it. Yet the butterfly also flew for us, on three days in September, above Sangay and me.

Record: 4, 5 and 19 September 2026. Many in flight, and also on flowers, including Swertia paniculata.

Photographs of Bhutanitis lidderdalii: Tandin Wangdi / September 19, 2026 / Trashigang, Bhutan Glory Wildlife Trail

Photograph of Sangay and Tandin: Dr. Rudra Prasad Das

18/09/2026

Butterfly Expert from India, Monsoon Jyoti Gogoi (PhD), said, “Trashi Yangtse is already well known for the Ludlow’s Bhutan glory, which is found nowhere else in the world. But additionally, our target is to document more species from the area, so that tourists not only come for Ludlow’s Bhutan glory, but also come for other rare butterflies. That was the target, and till now, we have been able to document quite a lot of species.”

𝗕𝘂𝘁𝘁𝗲𝗿𝗳𝗹𝘆 𝗠𝗲𝗲𝘁 𝗱𝗼𝗰𝘂𝗺𝗲𝗻𝘁𝘀 𝟭𝟬𝟯 𝘀𝗽𝗲𝗰𝗶𝗲𝘀 𝗶𝗻 𝗧𝗿𝗮𝘀𝗵𝗶 𝗬𝗮𝗻𝗴𝘁𝘀𝗲

Butterflies can be indicators of a healthy environment. Trashi Yangtse is home to more than 400 species of butterflies, including Bhutan’s national butterfly, Ludlow’s Bhutan Glory. Protecting these species and their habitats is crucial, especially as climate change continues to affect ecosystems.

https://www.bbs.bt/246450/

18/09/2026

Second Edition Bhutan Butterfly Meet

Trashiyangtse, Bhutan
Day 3 Field Report: Phordung–Old Dzong & Bimkhar-Tshergom

17 September 2026 | Prepared by Trashi Yangtse Nature Club

Day 3 Field Activity

Day 3 covered two sites in a single day. The morning walk took participants from Phordung to the Old Dzong of Trashiyangtse, tracing the historic fortress grounds overlooking the confluence of the Dongdi Chhu and Kholong Chhu, through a mix of forest edge and farmland close to town. In the afternoon, the group relocated to Bimkhar-Tshergom for a second walk through different terrain, giving the day a broader habitat sweep than the single-site walks of Day 1 and Day 2.

The day again closed with the Meet's evening checklist and knowledge-sharing session, where participants pooled sightings from both sites and confirmed identifications together before compiling the consolidated Day 3 list.

Highlight of the Day

Day 3 produced the richest single-day list of the Meet so far: 62 species, against 38 on Day 1 and 44 on Day 2. Cross-referencing all three days' checklists, the Meet's running tally now stands at 62 distinct species, closing in fast on the roughly 100-species target set for the four-day Meet, and a strong result for a September outing that falls outside Trashiyangtse's peak butterfly season.

The team found Branded Evening Brown and took second live photography ever in the world.

Covering two distinct sites in one day clearly paid off, with strong representation from the Nymphalidae: Circe, Stately Nawab, Large Silverstripe, Grand Duchess and Popinjay were among the more striking additions to the Meet's cumulative list. The day also turned up two Jezebels (Dark and Hill) and two Sergeants (Bhutan and Himalayan) side by side, along with the range-restricted Restricted Purple Sapphire.

Methodology

Records were gathered opportunistically at both sites through direct observation and photography, and reviewed collectively during the evening checklist session. The species list below follows the field checklist maintained by team, with two apparent spelling slips corrected for this report: Aulocera saraswati (Striated Satyr) and Lethe insana (Common Forester).

Results: Species Recorded: Day 3

A total of 62 species were confirmed across the two sites on Day 3, spanning six families: Nymphalidae, Papilionidae, Pieridae, Lycaenidae, Riodinidae and Hesperiidae.

No. Common Name Scientific Name Family

1 Common Peacock Papilio polyctor Papilionidae
2 Red Helen Papilio helenus Papilionidae
3 Spangle Papilio protenor Papilionidae
4 Common Grass Yellow Eurema hecabe Pieridae
5 Dark Jezebel Delias berinda Pieridae
6 Green-veined White Pieris napi Pieridae
7 Hill Jezebel Delias belladonna Pieridae
8 Indian Cabbage White Pieris canidia Pieridae
9 Albocerulean Udara albocaerulea Lycaenidae
10 Azure Sapphire Heliophorus moorei Lycaenidae
11 Blue Tit Chliaria kina Lycaenidae
12 Pale Grass Blue Pseudozizeeria maha Lycaenidae
13 Purple Sapphire Heliophorus epicles Lycaenidae
14 Lesser Grass Blue Zizina otis Lycaenidae
15 Restricted Purple Sapphire Heliophorus elda Lycaenidae
16 Transparent Six-line Blue Nacaduba kurava Lycaenidae
17 Dark Sapphire Heliophorus brahma Lycaenidae
18 Orange Punch Dodona egeon Riodinidae
19 Striped Punch Dodona adonira Riodinidae
20 Tailed Punch Dodona eugenes Riodinidae
21 Banded Treebrown Lethe confusa Nymphalidae
22 Blue Forester Lethe scanda Nymphalidae
23 Branded Evening Brown Melanitis leda Nymphalidae
24 Common Forester Lethe insana Nymphalidae
25 Confusing Threering Ypthima confusa Nymphalidae
26 Himalayan Fivering Ypthima sakra Nymphalidae
27 Moore's Bushbrown Mycalesis heri Nymphalidae
28 Lilacfork Lethe sura Nymphalidae
29 Pallid Argus Callerebia scanda Nymphalidae
30 Striated Satyr Aulocera saraswati Nymphalidae
31 Rusty Forester Lethe dura Nymphalidae
32 Chestnut Tiger Parantica sita Nymphalidae
33 Striped Blue Crow Euploea mulciber Nymphalidae
34 Bhutan Sergeant Athyma jina Nymphalidae
35 Blue Admiral Kaniska canace Nymphalidae
36 Blue Pansy Junonia orithya Nymphalidae
37 Bluetail Jester Symbrenthia niphanda Nymphalidae
38 Chocolate Soldier Junonia iphita Nymphalidae
39 Circe Hestina nama Nymphalidae
40 Common Commodore Auzakia danava Nymphalidae
41 Common Jester Symbrenthia lilaea Nymphalidae
42 Green Duke Euthalia sahadeva Nymphalidae
43 Himalayan Sergeant Athyma opalina Nymphalidae
44 Indian Fritillary Argyreus hyperbius Nymphalidae
45 Indian Red Admiral Vanessa indica Nymphalidae
46 Indian Tortoiseshell Aglais caschmirensis Nymphalidae
47 Large Silverstripe Childrena childreni Nymphalidae
48 Pallas's Sailer Neptis sappho Nymphalidae
49 Popinjay Stibochiona nicea Nymphalidae
50 Stately Nawab Polyura dolon Nymphalidae
51 Tabby Pseudergolis wedah Nymphalidae
52 White Commodore Parasarpa dudu Nymphalidae
53 Blue Duchess Euthalia duda Nymphalidae
54 Grand Duchess Euthalia patala Nymphalidae
55 Spotted Demon Notocrypta feisthamelii Hesperiidae
56 Veined Scrubhopper Aeromachus stigmatus Hesperiidae
57 Yellow-spot Swift Polytremis eltola Hesperiidae
58 Mussoorie Bush Bob Pedesta masuriensis Hesperiidae
59 Himalayan Swift Polytremis discreta Hesperiidae
60 Purple Red-eye Matapa sasivarna Hesperiidae
61 Common Dart Potanthus pseudomaesa Hesperiidae
62 Pygmy Scrubhopper Aeromachus pygmaeus Hesperiidae

Observations

Many species carried over from the first two days, Dark Jezebel, Azure and Purple Sapphire, Tailed Punch, Pallid Argus, Striated Satyr, Chestnut Tiger, Striped Blue Crow, Bhutan Sergeant, White Commodore, Common and Bluetail Jester, Pallas's Sailer, Blue Pansy, Spotted Demon, and Indian Red Admiral and Tortoiseshell all reappeared, confirming these as reliable, widespread species across the Trashiyangtse valley. The Old Dzong-Phordung and Bimkhar-Tshergom sites also added a wave of Nymphalinae and Limenitidinae not yet seen on the Meet's list, including the Commodores, Duchesses, Nawab and Fritillary, pointing to the value of the mixed forest-farmland edge around the old fortress and town for this group.

Day 4 takes the Meet from Yangtse to Bumdeling and on to Pamadung, before the day's field walk gives way, at 4 PM, to expert presentations for a wider audience of forest rangers, students and other butterfly enthusiasts joining the core group of researchers and photographers. With the running tally already at 62 species after three days, the Trashi Yangtse Nature Club is optimistic that the Meet's roughly 100-species target is well within reach by the close of Day 4, a strong showing for a Meet held outside peak butterfly season.

17/09/2026

Second Edition Bhutan Butterfly Meet / Day 3

Day 3 produced the richest single-day list of the Meet so far: 63 species, against 39 on Day 1 and 44 on Day 2. Covering two distinct sites in one day clearly paid off, with strong representation from the Nymphalidae such as Circe, Stately Nawab, Large Silverstripe, Grand Duchess and Popinjay were among the more striking additions to the Meet's cumulative list. The day also turned up two Jezebels (Dark and Hill) and two Sergeants (Bhutan and Himalayan) side by side, along with the range-restricted Restricted Purple Sapphire.

Methodology

Records were gathered opportunistically at both sites through direct observation and photography, and reviewed collectively during the evening checklist session.

Observations

Many species carried over from the first two days: Dark Jezebel, Azure and Purple Sapphire, Tailed Punch, Pallid Argus, Striated Satyr, Chestnut Tiger, Striped Blue Crow, Bhutan Sergeant, White Commodore, Common and Bluetail Jester, Pallas's Sailer, Blue Pansy, Spotted Demon, and Indian Red Admiral and Tortoiseshell all reappeared, confirming these as reliable, widespread species across the Trashiyangtse valley. The Old Dzong-Phordung and Bimkhar-Tshergom sites also added a wave of Nymphalinae and Limenitidinae not yet seen on the Meet's list, including the Commodores, Duchesses, Nawab and Fritillary, pointing to the value of the mixed forest-farmland edge around Old Dzong and new farm road for this group.

Bhutan Butterfly Society(BSoB)
Bumdeling Wildlife Sanctuary

Full report in the next post.

Photographs: Tshulthrim Wildlifer and Pema Norbu