The El Hierro Grayling (Hipparchia bacchus) is endemic to the Canary Island of El Hierro. The area of occupancy of this species is estimated to be 56 km² and it occurs in only two locations, which are both threatened by volcanic activity which could feasibly drive it to Critically Endangered in a short period of time. It has therefore been assessed as Vulnerable D2.

This species is endemic to the European region where it is restricted to two locations on the Canary Island of El Hierro (Spain). It is found at altitudes between 300 and 700 m.

This is a very local and rare European endemic, restricted to two (semi-) natural areas on El Hierro, Canary Islands. The total population is thought to be well under 10,000 and it is still common in specific places. These populations are at great risk from volcanic eruptions (see Threats section).

The El Hierro Grayling is confined to one of the Canary Islands, El Hierro, where it can be found on the very steep and grassy cliffs and the vineyards at the base of the cliffs. It has one generation a year (Tolman and Lewington 2008).

This species is restricted to two locations on one island and populations are at great risk from volcanic eruptions. The last eruption that occurred on El Hierro in 2011 initially threatened to erupt precisely in the area where this species lives, with large deformations of the terrain that raised the island by several centimetres. Finally, the eruption was underwater, in an area to the south of the island. This represents a plausible threat that would drive it to Critically Endangered in a short time. See https://digital.csic.es/bitstream/10261/199393/1/Erupcion_Submarina-VSoler-EG12.pdf (Y. Monasterio, pers.comm.). The butterfly is found in an agricultural environment, where the use of synthetic chemicals is widespread and the impact on its immature stages is unknown. This threat must be taken into account as a potentially important factor for its conservation.

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.

As this species has a restricted global range and is very rare, important sites should be protected and managed appropriately, particularly expanding habitat when possible, plus researching and managing key threats, such as pesticides. Its distribution, trend and habitat should also be monitored closely, for example by a butterfly monitoring scheme.