European regional assessment: Near Threatened (NT)
EU 27 regional assessment: Vulnerable (VU)

Within the European region, Nogel's Hairstreak occurs in Romania, Moldova, Ukraine and southern European Russia. This species is listed as Near Threatened for Europe because it has severely fragmented populations and a small area of occupancy of less than 100 km², therefore it is close to qualifying under criterion B2. This species is listed as Vulnerable D2 for the EU 27 region because it has a restricted area of occupancy and number of locations where the absence of suitable management could drive the species to extinction in a very short space of time.

Within the European region, this species occurs in Romania, Moldova, Ukraine and southern European Russia. It is found at altitudes between sea level and 100 m.

In the EU 27 region, this species' area of occupancy is 8 km² and the extent of occurrence is 130 km².

The global range of this species extends to Türkiye, the Caucasus and the western Middle East (Syria, Lebanon, Palestine). The global distribution area of the species is situated both within and outside Europe.

This is a local species, restricted to (semi-) natural habitats and occurs in small isolated populations. Declines in distribution or population have been reported in several countries. It is classed as Critically Endangered in Romania; and Endangered in Ukraine (Maes et al. 2019).

The only known populations in the EU 27 occur in North Dobrogea, Romania. Another population became extinct in the Galati area (Moldova District) in 1975 and an adult was observed 15 years about 85 km from the known sites but the locality of this population also remains undiscovered.

Until recently only one site was known in Romania, occupying about 1 km² of habitat whose population was estimated to be about 200 individuals in good years (based on counts in 2022). The presence of one or two undiscovered populations where the hostplants persisted were suspected for some time (L. Rákosy pers.comm.) and these have been recently confirmed by surveys in 2022-23 (L. Caekebeke pers. comm.). The number of populations in Romania remains uncertain, but nearly 30 occupied habitat patches have been discovered. Many of these patches are small with just a few hostplants. The majority of patches are close-by suggesting those constitute a single metapopulation, although some are many kilometres apart. It is unclear if the more isolated patches represent temporary stepping stones in the landscape, separate subpopulations, populations, or metapopulations. The size of these newly discovered low density populations are estimated at around 100 individuals (L. Caekebeke pers. comm.). The core area in which the butterfly occurs is approximately 30 km² in area but the extent of occurrence may extend to 180 km² (L. Caekebeke pers. comm.) However, the hostplant occupies less than 10 km² of habitat (L. Rákosy pers.comm.).

No information is available on the current status of Nogel's Hairstreak in Moldova and Ukraine. However, across its range, populations appear to be small and isolated from each other and are therefore considered to be severely fragmented.

Nogel’s Hairstreak inhabits very open, dry woodland, dry grasslands in woodland areas and steep slopes. In Romania, the species was recently only found in open broad-leaved deciduous forests and wood pastures (Lieven Caekebeke, pers.comm.).

Its main larval hostplant is the milk-vetch Astragalus ponticus. It has one generation a year and hibernates as a pupa. Habitats are dry calcareous grasslands and steppes (60%), phrygana (20%), broad-leaved deciduous forests (20%) (van Swaay et al. 2006).

Nogel's Hairstreak is a nearly monophagous habitat specialist with a highly fragmented distribution, of which little is known. The butterfly is threatened by a lack of a suitable grassland/scrub/woodland habitat management (both agricultural intensification and abandonment). The hostplant benefits from regular soil disturbance by wild boar, other wild grazers, cattle or sheep. However, overgrazing of grasslands and wood pastures is detrimental and only low intensity grazing is beneficial.

Some populations have been impacted in the past by tourism developments. Habitat loss and changing habitat quality have also led to increasing habitat fragmentation and isolation of remaining populations and subpopulations.

All butterflies are collected to some extent, but only for the extremely rare species can it be a problem and the trade in Europe is generally at a low level compared to other continents. There is no specific trade information for this species.

It is not known if this species occurs in any protected areas outside of Romania, where it only occurs in Natura 2000 sites. Further research is needed on the distribution and ecology of the species. Protecting remaining sites from further destruction should be a priority. Suitable habitats should be protected and appropriately managed. The effects of conservation actions should be monitored by butterfly monitoring schemes.