Thoressa varia
In 3 days ~10% in a week ~30%
Thoressa varia is a butterfly of the family Hesperiidae. It is found on the islands of eastern Asia, including the Sakhalin Islands and Kuril Islands, Japan, the Korean Peninsula and north-eastern China. Its Japanese common name kochabane-seseri can be translated as "small brown wing" (ko means "small" and chabane means "brown wings").
The length of the forewings is 16–18 mm. Adults are on wing each year from June to July. There are one to two generations per year. The larvae feed on Sasa kurilensis. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Nikko National Park | 🇯🇵 Japan |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Tokyo | 🇯🇵 Japan |
Rare
Under 5% of wildlife watchers report a Japanese Swift sighting in Tokyo on a given day, based on 56 verified sightings from GBIF citizen-science data. It is the 257th most-seen of the 1013 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
April–May and July
In those months about 10% of wildlife watchers report a Japanese Swift in Tokyo on a given day, against under 5% in June and August–March, the lowest months.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Japanese Swift sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Only Tokyo, in our data
Tokyo is the only city on Wallace's Line with enough records to rate Japanese Swift sightings: under 5% of wildlife watchers there report one on a given day.
Same family: Hesperiidae
The closest relatives of the Japanese Swift that you can see in Tokyo (family Hesperiidae, Skippers) are Common Straight Swift (about 20%), Small Branded Swift (about 10%) and Japanese Dart (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Japanese Swift is recorded against all the insects logged in Tokyo (56 verified sightings), 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.
