The Bombay night frog (Nyctibatrachus humayuni) is a small, nocturnal stream frog endemic to the northern Western Ghats of India, best known for a mating behaviour in which the male sits on the female’s back without gripping her and fertilisation happens without the usual body contact. It lives along rocky forest streams in the Mumbai region and nearby hill country of Maharashtra, and it is a good example of the Ghats’ hidden amphibian diversity.
The Bombay night frog belongs to the night frogs, a family found only in the Western Ghats and Sri Lanka’s wet zone, and it has become a favourite subject of Indian herpetologists since a 2016 study described its unusual breeding. This explainer covers its identification, habitat, reproduction, the conservation risks it faces and the ways people can help.
| Attribute | Detail |
|---|---|
| Common names | Bombay night frog, Humayun’s night frog |
| Scientific name | Nyctibatrachus humayuni |
| Family | Nyctibatrachidae (night frogs) |
| Described | 1955, from the Bombay region |
| Size | Small; adults are only a few centimetres long |
| Range | Northern Western Ghats, mainly Maharashtra, in and around the Mumbai region and nearby hills |
| Habitat | Rocky, forested streams with leaf litter and wet boulders |
| Activity | Nocturnal; breeds around the monsoon |
| Notable feature | Dorsal straddle: a male rides the female’s back during breeding without clasping her |
Key Takeaways
- The Bombay night frog (Nyctibatrachus humayuni) is a small nocturnal frog found only in the northern Western Ghats of India, mainly around Mumbai and in the hills of Maharashtra.
- The Bombay night frog was described in 1955 and its scientific name humayuni honours the Indian ornithologist Humayun Abdulali.
- The Bombay night frog attracted worldwide attention in 2016, when researchers reported that its pairs breed in a “dorsal straddle” position, without the clasping hold seen in most frogs.
- The same study found that female Bombay night frogs also produce a call, which is uncommon among frogs, where mostly males call.
- The Bombay night frog depends on clean, rocky, forest-shaded streams, so stream pollution, quarrying and urban spread are its main threats.
- The Bombay night frog is harmless to people and is a useful indicator of the health of small hill streams in the northern Western Ghats.
What is the Bombay night frog?
The Bombay night frog is a stream-dwelling frog of the genus Nyctibatrachus, whose members are called night frogs because they are active mainly after dark. Its species name humayuni honours Humayun Abdulali (1914-2001), a Mumbai naturalist best known for his work on birds, who collected in the region.
The frog has a rounded body, large dark eyes, smooth to finely textured skin, long slender limbs and a mottled brown, olive or greyish pattern that blends into wet rock and leaf litter. The toes are partly webbed, which helps it move over slippery stones and swim in shallow water.
Frogs of this genus are among the least known amphibians of India. Before intensive surveys began in the 2000s, they were often overlooked because they are small, cryptic and live in places that are difficult to reach during the heavy monsoon rains.
What are night frogs, and how many species are there?
Night frogs are the members of the family Nyctibatrachidae, and more than 30 species are now known, nearly all of them confined to the Western Ghats. The genus Nyctibatrachus has expanded rapidly in recent decades as researchers have described many new forms from different hill ranges.
This family is a classic example of Western Ghats endemism. The Ghats are a UNESCO World Heritage Site and one of the world’s biodiversity hotspots, and they hold hundreds of amphibian species, a majority of which are found nowhere else. The night frogs are part of an ancient lineage that split from other frogs a very long time ago, which is why scientists value them for studies of evolution.
How can it be told apart from other stream frogs?
The Bombay night frog is best identified by its habitat, its geographic range and fine details of skin and body shape, and it is difficult to separate from its relatives by eye alone. Field guides and expert comparison are needed for a firm identification, and for some night frogs the call or a genetic test is the deciding factor.
Where does the Bombay night frog live?
The Bombay night frog lives in the northern part of the Western Ghats, in forest streams in and near Mumbai and in neighbouring hill districts of Maharashtra. It prefers clear, shaded, rocky streams that run through evergreen or semi-evergreen forest and keep water for much of the year.
During the day, the frog hides under stones, in crevices and in leaf litter close to the stream. At night it emerges to sit on wet rocks and bankside vegetation. Because it needs both flowing water and moist forest around it, the species cannot live in open, cleared or polluted stretches.
Its known range is limited, and many localities lie close to a large and growing urban area, a combination that raises its conservation concern.
How does the Bombay night frog breed?
The Bombay night frog breeds during the monsoon season, with males calling from rocks beside streams and a pair then forming a dorsal straddle, in which the male sits on the female’s back without clasping her. This is very different from the usual frog breeding position, called amplexus, in which the male grips the female tightly around the body.
The unusual behaviour was described in a 2016 paper published in the journal PeerJ by a team of Indian and Belgian researchers that included the University of Delhi herpetologist S. D. Biju. The authors reported a new form of amplexus and a method of fertilisation without physical contact between the male’s and the female’s cloacae, along with a female call.
The key contrasts with the typical frog pattern are summarised below.
| Feature | Typical frog breeding | Bombay night frog |
|---|---|---|
| Male position | Grips the female tightly around the body or waist | Sits on the female’s back without a grip (dorsal straddle) |
| Fertilisation | External, with the male’s cloaca close to the female’s | External, without direct cloacal contact |
| Calling | Usually only males call | Males call and females also produce a call |
| Egg site | Often water or foam nests | Streamside rock or vegetation, with tadpoles developing in the stream |
The finding is important because it shows that even a well-known city-fringe amphibian can hold unexpected biology. It also suggests that other night frogs may have equally unusual reproductive habits that remain unstudied.
How does the Bombay night frog communicate?
The Bombay night frog communicates mainly through sound, with males calling at night from rocks and low perches near the stream to attract females. Calls are short and soft and are partly drowned out by running water, which means that the frog is often heard only at close range.
Sound is the main tool for finding mates in the dark, and the call of each frog species is distinctive. Researchers therefore record calls to separate similar species and to confirm that populations at different sites belong to the same species. The 2016 observation that females also call added a new element to this picture, since it suggests that two-way acoustic communication may help partners find and coordinate with each other before the dorsal straddle begins.
For the public, listening is also a simple way to take part in frog monitoring. Organised monsoon frog walks near Mumbai and in the Ghats help naturalists to record which species are present, as long as visitors keep to trails and do not handle the animals.
Why are the Western Ghats so important for frogs?
The Western Ghats are important for frogs because their combination of heavy monsoon rain, ancient forests and many separate hill ranges has produced an exceptional number of endemic amphibians. The mountain chain runs for roughly 1,600 kilometres along India’s west coast, and different ranges and plateaus act like islands that isolate small populations.
Over a very long time, isolation has allowed new species to evolve in each block of forest. This is why scientists continue to describe new frogs from the Ghats, including night frogs, bush frogs and burrowing frogs, and why many species are known from only a handful of sites.
The Bombay night frog lives at the northern end of this chain, where forest patches are smaller and closer to large cities than in the southern Ghats. That position makes it a particularly useful species for studying how urban growth affects wildlife.
What does the Bombay night frog eat?
The Bombay night frog eats small invertebrates such as insects, spiders and other creatures that it finds near the water at night. Like most frogs, it sits and waits for movement, then captures prey with a quick lunge of its tongue.
The frog, in turn, becomes food for snakes, crabs, birds and larger frogs. As part of a stream community, it moves nutrients from the insects of the forest floor to the predators of the stream bank.
The tadpoles of night frogs are adapted to streams, and many cling to rocks or hide in crevices to avoid being swept away. They graze on algae and organic film on the stones.
Is the Bombay night frog endangered?
The Bombay night frog is considered a species of conservation concern because its range is small and its stream habitat is under pressure, and the IUCN has placed it in a threatened category. Local populations can fall quickly when a stream is dammed, polluted or cleared.
The main threats include the following.
- Urban expansion: Housing, roads and industry around Mumbai and other towns of the northern Ghats take over forest and pollute streams.
- Quarrying and mining: Rock extraction destroys stream beds and boulders where the frog lives.
- Tourism pressure: Monsoon crowds at waterfalls and streams trample banks and leave waste.
- Climate change: More erratic rainfall may shorten the period of flowing water on which breeding depends.
- Pollution: Sewage, plastics and chemicals harm the thin, permeable skin of amphibians.
Amphibians in general are among the most threatened vertebrates in the world, and their permeable skin makes them very sensitive to changes in water quality. That sensitivity is why they are often described as early warning indicators of environmental trouble.
Why does the Bombay night frog matter?
The Bombay night frog matters because it is an indicator of clean, forested streams, a living example of the Western Ghats’ endemism and a source of new scientific knowledge. A healthy population suggests that the stream still functions as a natural system, with clear water, intact banks and a rich insect community.
It is also an important teaching species. The discovery of its unusual mating shows that fundamental biological questions can still be answered with fieldwork near a major Indian city, and it has encouraged citizen scientists to record frogs in the monsoon.
Frogs also control insects, including some pests and mosquitoes, so a thriving amphibian community brings indirect benefits to people living near forests.
How can people help protect the Bombay night frog?
People can help protect the Bombay night frog by keeping forest streams clean, avoiding disturbance of stream banks, supporting protected areas and recording frog sightings responsibly. Small actions by visitors and local residents have a real effect on a species with such specific habitat needs.
- Do not collect or handle frogs; their skin is delicate, and oils and lotions on hands can harm them.
- Carry all waste out of forest areas and avoid using soaps or chemicals in streams.
- Stay on trails near streams during the monsoon, when frogs breed on the banks.
- Support habitat protection near Mumbai, including stream buffers and forest cover.
- Share verified observations with local naturalist groups and with platforms that support biodiversity research.
Researchers also stress the need for regular monitoring, since without baseline counts it is hard to say whether populations are stable, rising or falling.
How do scientists study the Bombay night frog?
Scientists study the Bombay night frog through night-time stream surveys, sound recordings, behavioural observation with low-light cameras and genetic analysis of tissue samples. Because the frog is small and the monsoon streams are hazardous, careful and patient fieldwork is essential.
The breeding discovery came from such close observation of animals in natural settings and in controlled viewing. Genetic studies also help to place night frogs on the evolutionary tree and to reveal hidden species that look alike. These tools together give conservation planners the facts they need to decide which stream stretches deserve protection.
Bottom Line
The Bombay night frog is a small, shy, stream-bound amphibian of the northern Western Ghats whose unusual breeding behaviour has made it scientifically famous. Its survival depends on keeping hill streams clean and forested, and protecting it protects a wider community of Ghats wildlife.
Frequently Asked Questions
What is the Bombay night frog?
The Bombay night frog (Nyctibatrachus humayuni) is a small, nocturnal stream frog endemic to the northern Western Ghats of India. It is best known for its unusual breeding behaviour.
Why is the Bombay night frog famous?
The Bombay night frog is famous because a 2016 study reported a new mating position, the dorsal straddle, in which the male sits on the female’s back without clasping her. The study also described a female call, which is uncommon in frogs.
Where is the Bombay night frog found?
The Bombay night frog is found in the northern Western Ghats, mainly in forest streams in and around the Mumbai region and nearby hills of Maharashtra. It needs clean, shaded, rocky streams.
Why is it called a night frog?
It is called a night frog because members of the genus Nyctibatrachus are active mainly after dark. The name comes from Greek roots meaning night and frog.
Is the Bombay night frog endangered?
The Bombay night frog is regarded as a species of conservation concern, with the IUCN placing it in a threatened category because of its small range and vulnerable stream habitat. Urban growth, quarrying and pollution are the main threats.
Is the Bombay night frog harmful to humans?
No, the Bombay night frog is completely harmless to people. It is shy, stays near its stream and is best observed without touching, since handling can damage its delicate skin.
{“@context”:”https://schema.org”,”@graph”:[{“@type”:”FAQPage”,”mainEntity”:[{“@type”:”Question”,”name”:”What is the Bombay night frog?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”The Bombay night frog (Nyctibatrachus humayuni) is a small, nocturnal stream frog endemic to the northern Western Ghats of India. It is best known for its unusual breeding behaviour.”}},{“@type”:”Question”,”name”:”Why is the Bombay night frog famous?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”The Bombay night frog is famous because a 2016 study reported a new mating position, the dorsal straddle, in which the male sits on the female’s back without clasping her. The study also described a female call, which is uncommon in frogs.”}},{“@type”:”Question”,”name”:”Where is the Bombay night frog found?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”The Bombay night frog is found in the northern Western Ghats, mainly in forest streams in and around the Mumbai region and nearby hills of Maharashtra. It needs clean, shaded, rocky streams.”}},{“@type”:”Question”,”name”:”Why is it called a night frog?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”It is called a night frog because members of the genus Nyctibatrachus are active mainly after dark. The name comes from Greek roots meaning night and frog.”}},{“@type”:”Question”,”name”:”Is the Bombay night frog endangered?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”The Bombay night frog is regarded as a species of conservation concern, with the IUCN placing it in a threatened category because of its small range and vulnerable stream habitat. Urban growth, quarrying and pollution are the main threats.”}},{“@type”:”Question”,”name”:”Is the Bombay night frog harmful to humans?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”No, the Bombay night frog is completely harmless to people. It is shy, stays near its stream and is best observed without touching, since handling can damage its delicate skin.”}}]}]}
