Pareas formosensis
Silhouette: Marius Burger (photograph) · PhyloPic
In 3 days ~80% in a week >90%
Formosa slug snake or Taiwan slug snake (Pareas formosensis) is a species of non-venomous snake in the family Pareatidae. It is endemic to Taiwan. It has been suggested that Pareas chinensis should be treated as a synonym of P. formosensis, but recent genetic research does not support this: P. formosensis does not appear closely related to P. chinensis but is instead a sister species to P. hamptoni. The delineation of these species is not clear. In future, P. formosensis might become a subspecies of P. hamptoni, or some snakes from the mainland might be classified as P. formosensis.
Further studies have shown that Pareas komaii is a valid species, instead of being a synonym of P. formosensis. The study also described a new species, Pareas atayal, that have been confused with P. formosensis. Thus, three Pareas species occur in Taiwan.
The Formosa slug snake is a small snake with total length up to 70 cm (28 in). These snakes are widespread in mountainous, moist forests. Formosa slug snakes are nocturnal and feed on land snails and slugs. Female snakes produce a clutch of 2–9 eggs; the hatchlings measure about 15 cm (5.9 in) in total length.
P. formosensis... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cuc Phuong National Park | 🇻🇳 Vietnam |
More parks will be added in future updates.
No species of the same family or order lives in Cuc Phuong National Park, so these are its closest relatives here: other reptiles.
Likely
About 40% of wildlife watchers report a Formosa Slug Snake sighting in Cuc Phuong National Park on a given day, based on 13 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 5th most-seen of the 16 reptiles we can rate there. Over three days the chance rises to about 80%, and over a week to over 90%, if each day is a fresh chance.
August and November
In those months about 60% of wildlife watchers report a Formosa Slug Snake in Cuc Phuong National Park on a given day, against under 5% in July, the lowest month.
Between 3 and 6 pm
Across all the parks we cover, that three-hour window holds the most Formosa Slug Snake sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Cuc Phuong National Park, in our data
Cuc Phuong National Park is the only park on Wallace's Line with enough records to rate Formosa Slug Snake sightings: about 40% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Formosa Slug Snake is recorded against all the reptiles logged in Cuc Phuong National Park (13 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.
