Biston strataria
In 3 days ~10% in a week ~20%
Biston strataria, the oak beauty, is a moth of the family Geometridae. It is native to Europe, the Balkan countries and the Black Sea region as far as Asia Minor and the Caucasus. The species was first described by Johann Siegfried Hufnagel in 1767. B. strataria is found in a variety of habitats, but is mostly found in woodlands where it rests on the bark of trees, camouflaged by its mottled black and grey wings. The male has feather-like antennae while those of the female are more thread-like. The moth has a wingspan of 40 to 56 mm (1.6 to 2.2 in).
The larvae are mainly brown with three lumps near the end of the abdomen. They have evolved to resemble sticks which helps protect them from predators. The larvae feed on many species of trees, but the most commonly used host plants are oaks.
The oak beauty has white forewings with two irregular broad brown bands along each wing. The first band is short, located near the base of the wing, and surrounded with a black border. The second band is located near the outer margin with a black border surrounding the inner edge. Between these two bands is a white space sprinkled with black dots as well as a crescent-shaped black... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 3 | Sierra de Guadarrama National Park | 🇪🇸 Spain | |
| 4 | Wadden Sea National Park | 🇩🇪 Germany | |
| 5 | Pyrénées National Park | 🇫🇷 France |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Liverpool | 🇬🇧 United Kingdom | |
| 2 | Porto | 🇵🇹 Portugal | |
| 3 | London | 🇬🇧 United Kingdom | |
| 4 | Birmingham | 🇬🇧 United Kingdom | |
| 5 | Helsinki | 🇫🇮 Finland | |
| 6 | Copenhagen | 🇩🇰 Denmark | |
| 7 | Prague | 🇨🇿 Czechia | |
| 8 | Berlin | 🇩🇪 Germany | |
| 9 | Vienna | 🇦🇹 Austria | |
| 10 | Moscow | 🇷🇺 Russia |
Rare
Under 5% of wildlife watchers report a European Oak Beauty sighting in Helsinki on a given day, based on 9 verified sightings from GBIF citizen-science data. It is the 509th most-seen of the 838 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
April
In that month about 10% of wildlife watchers report a European Oak Beauty in Helsinki on a given day, against under 5% in May to March, the lowest months.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most European Oak Beauty sightings with a recorded time, and about half of them come between 6 pm and 6 am: it is seen both by day and at night.
5th of 10
Of the 10 cities where we can rate European Oak Beauty sightings, Helsinki ranks 5th at under 5%. The best odds are in Liverpool (United Kingdom, about 10%), Porto (Portugal, about 10%) and London (United Kingdom, about 10%).
GBIF citizen-science records
It is estimated from how often the European Oak Beauty is recorded against all the insects logged in Helsinki (9 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.
