Fixsenia pruni
In 3 days ~10% in a week ~20%
The black hairstreak (Satyrium pruni) is a butterfly in the family Lycaenidae. The butterfly is native to Europe, from Scandinavia to Ukraine, and is found as far east as Mongolia, Korea and Japan. It is considered by IUCN to be stable and of least concern.
T. pruni L. (73 d). Above in the male with a few anal spots, in the female an anal halfband and sometimes a discal spot brick-red. Beneath the line of white bars is very thin, and the brick-red submarginal band of the hindwing is placed between two rows of black spots, which are thinly edged with bluish white, and is sometimes continued on to the forewing. Throughout Central and South Europe, from the Atlantic coast and Great Britain throughout Europe and Asia to Amurland and Corea; but absent from North Africa and probably also from Japan, the specimens recorded from the latter country presumably belonging to mera or prunoides In ab. fulvior Tutt (particularly females) the forewing bears an orange-yellow discal patch, the rest of the wing being dusted with golden brown. In ab. ptorsas Hfngl. both wings have a reddish yellow submarginal band above; transitional specimens have an incomplete... Wikipedia →
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More parks will be added in future updates.
Rare
Under 5% of wildlife watchers report a Black Hairstreak sighting in Vienna on a given day, based on 25 verified sightings from GBIF citizen-science data. It is the 505th most-seen of the 1406 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.
May and June
In those months about 10% of wildlife watchers report a Black Hairstreak in Vienna on a given day, against under 5% in July to April, the lowest months. Those are among Vienna's wettest months, with about 90 mm of rain a month against 40 mm in February.
4th of 8
Of the 8 cities where we can rate Black Hairstreak sightings, Vienna ranks 4th at under 5%. The best odds are in Kharkiv (Ukraine, about 10%), Prague (Czechia, under 5%) and Seoul (South Korea, under 5%).
Same family: Lycaenidae
The closest relatives of the Black Hairstreak that you can see in Vienna (family Lycaenidae, Gossamer-winged Butterflies) are Common Blue (about 20%), Sooty Copper (about 10%) and Holly Blue (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Black Hairstreak is recorded against all the insects logged in Vienna (25 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.
