Hydrochous gigas
Silhouette: Aviceda (vectorized by T. Michael Keesey) · PhyloPic
In 3 days ~20% in a week ~40%
The giant swiftlet (Hydrochous gigas), also known as the waterfall swift, is a species of bird in the swift family, Apodidae. It is the only member of the monotypic genus Hydrochous. It is found in Malaysia, Sumatra and Java, where its natural habitats are subtropical or tropical moist montane forests and rivers. It may be threatened by habitat loss.
The giant swiftlet has the largest average wingspan of all the swiftlets, at 150 millimeters. It is a fairly large swift that can grow to 16 cm in length. The female weighs 35 to 39 grams, and the male around 37 grams. Unlike other swiftlets, it builds its nest on a flat horizontal surface instead of molding it against a vertical surface with saliva.
It is not totally nocturnal, lacking the echolocation seen in some other swiftlets, but is still able to orientate visually in dim light. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Gunung Leuser National Park | 🇮🇩 Indonesia | |
| 2 | Kinabalu Park | 🇲🇾 Malaysia | |
| 3 | Kerinci Seblat National Park | 🇮🇩 Indonesia |
With luck
About 10% of wildlife watchers report a Waterfall Swift sighting in Gunung Leuser National Park on a given day, based on 15 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 85th most-seen of the 166 birds we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June and August
In those months about 20% of wildlife watchers report a Waterfall Swift in Gunung Leuser National Park on a given day, against under 5% in March, May, July and September–January, the lowest months.
Yes
Of the 3 parks where we can rate Waterfall Swift sightings, Gunung Leuser National Park has the highest daily chance: about 10%. Next come Kinabalu Park (Malaysia, under 5%) and Kerinci Seblat National Park (Indonesia, under 5%).
Same family: Apodidae
The closest relatives of the Waterfall Swift that you can see in Gunung Leuser National Park (family Apodidae, Swifts) are Plume-toed Swiftlet (about 20%), Black-nest Swiftlet (about 10%) and Silver-rumped Needletail (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Waterfall Swift is recorded against all the birds logged in Gunung Leuser National Park (15 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
