Lepus castroviejoi was described relatively recently, being separated from L. granatensis, a split supported by genetic evidence. While the range of L. castroviejoi partially overlaps that of L. granatensis and L. europaeus on the Iberian Peninsula, no hybridization has been detected with these forms. Recent studies have shown that instead, based on ecological, molecular and morphological characteristics, it is most closely related to L. corsicanus; some believe these two are conspecific (Alves et al. 2008, Acevedo et al. 2014, Ballesteros 2018). Additionally, two different occurrences of introgression of mtDNA from L. timidus into L. castroviejoi have been documented – indicating that these two forms have come into contact and hybridized two different times in the past, most recently during the last deglaciation (Melo-Ferreira et al. 2005, 2012; Ballesteros 2018). No subspecies or geographic variation in L. castroviejoi have been described (Flux and Angermann 1990, Hoffmann and Smith 2005, Ballesteros 2018).

The Broom Hare is endemic to Europe, where it is restricted to a relatively small geographic range in northern Spain with an extent of occurrence (EOO) of <8,500 km² and an area of occupancy (AOO) that is suspected to be less than 2,000 km². Within this range the species is severely fragmented, occupying highly specialized patches of scarce heath habitat. These fragmented subpopulations form a dispersed metapopulation within a matrix of unsuitable habitats. Population declines have been observed along the northern portion of its range and in the marginal habitat in which it occurs (Ballesteros 2003, 2007, 2018), the continuing decline is due to hunting, predation, poisoning and habitat change. The Broom Hare is listed as Vulnerable in Spain, although it is not included in the Spanish Catalog of Endangered Species or the Spanish List of Wildlife Species of Special Protection Regime. The species is listed as Vulnerable (VU B1ab(iii,v)+2ab(iii,v)).

The Broom Hare is restricted to the Cantabrian Mountains (northwestern Spain), where it occupies a small distribution range of about 5,000 km² (230 km long, 25–40 km wide) in the Spanish provinces of Lugo, León, Asturias, Palencia, and Cantabria. The species is found from the Sierra de los Ancares, between Lugo and León, up to Sierra de Peña Labra, between Cantabria and Palencia (Palacios and Meijide 1979). It occurs at elevations ranging from 1,000 to 1,900 m above sea level, with a highly fragmented distribution, as it occupies specialized patches of habitat within pastures and shrubland, sparse in a diverse mountain landscape (Ballesteros 2007, 2018). The range shows a differential distribution between the northern and southern slopes of the Cantabrian Mountains, because of the differences in orography and favourable habitat availability, with deep valleys and high altitudinal variations in the northern slope and broader highlands in the southern one. In some peripheral areas of its range, the Broom Hare is very scarce or has even disappeared (e.g., Peña Manteca or Sierra del Aramo in Asturias, Áliva or Peña Labra in Cantabria, Ballesteros 2009). In the southwest of Asturias, southeast of Galicia, and a large part of the southern limit of its distribution range in León, the Broom Hare contacts with the Iberian Hare. In the east of Cantabria and northeast of Palencia, the Broom Hare also comes in contact with the European Hare (Ballesteros and Alves 2022).

The EOO is estimated at 8,437 km². The AOO is 380 km² based on data available via GBIF (2024); whilst this is considered to be an under-estimate, it is likely that the AOO is less than 2,000 km².

Nocturnal censuses with spotlights have estimated average densities of 4.83/100 ha in Liébana (Cantabria), 6.89/100 ha in the Picos de Europa National Park (León), or between 8.83 and 23.32/100 ha in Somiedo (Asturias) (Acevedo et al. 2007, Ballesteros and Palacios 2009). The abundance of the Broom Hare is often evaluated using Kilometric Abundance Indexes (KAI) obtained through night surveys with spotlights. The average KAI value was 0.73 hares/km in Asturias in 1997 (varying between 0.21 and 1.51 in different areas), or 0.40 and 0.46 in the Picos de Europa National Park in 2006 and 2007, respectively (Ballesteros and Palacios 2009). No big fluctuations or cycles in relative abundance or density have been documented, but the analysis of 565 hare locations collected in a protected area (the Picos de Europa National Park) between 1988 and 2018 has shown high variability in the number of observations each year, although the survey effort applied in this period has been more or less similar. It is foreseeable that part of the interannual variability may be due to a variation in abundance as a consequence of the alternation of years of good and poor reproduction (Ballesteros and Palacios 2009, Ballesteros and Alves 2022).

The population size and detailed distribution range are unknown. The species is distributed in metapopulations occupying specific habitat patches through their distribution range. In a study conducted through surveys by rangers, 70.83% of local populations were considered stable, compared to 16.67% of declining and 4.17% of increasing populations (Acevedo et al. 2007). The peripheral populations seem to be suffering a more pronounced regression and even some local disappearance (Ballesteros 2009). Nevertheless, this information has over 10 years, and no recent data are currently available (Ballesteros and Alves 2022).

The species is severely fragmented, occupying highly specialized patches of scarce heath habitat. These fragmented subpopulations form a dispersed metapopulation within a matrix of unsuitable habitats.

The Broom Hare occupies a very characteristic habitat of the high-elevation areas in the Cantabrian Mountains. These areas are typically occupied by abundant open pastures or small herbaceous clearings of variable surface, surrounded by broom formations, heathers, thorny bushes, subalpine juniper and forests of beech, oaks, birch, and other species, located at altitudes varying between 1,000 and 1,900 m above sea level (Ballesteros and Alves 2022).

The Broom Hare continues to be considered as a game species in some parts of its range, and it is legally hunted across most of its range, with a low extraction level and controlled management plans. In addition, the Broom Hare may be easily visually confused by hunters with other hare species in some regions, namely when in contact areas with L. granatensis. Moreover, poaching using vehicles and spotlights at night is considered a major threat to this species.

Due to the general low population size and the fragmented distribution, even considering the limited number of hunted individuals, the effects of legal and illegal hunting on the evolution of the population should be carefully evaluated. As a precautionary principle, the hunting of this species should be avoided or strictly controlled throughout its distribution range, at least until more information is obtained about population size and trends in each area and the effect induced by hunting in its populations (Ballesteros and Alves 2022).

The species is impacted by habitat change and loss. The causes of this are not clear but are likely to include urbanisation and agricultural change.

Although the Broom Hare is listed as Vulnerable in Spain, it remains considered as a game species in some regions. Despite some local bans, currently, the Broom Hare is legally hunted across most of its range, with a low extraction level and controlled management plans. Legal hunting is usually developed by a group of hunters and several specialized dogs that capture a single specimen in each hunting event (Ballesteros and Alves 2022).

The Broom Hare is an endangered evolutionary significant unit (ESU), living in an isolated and very restricted region, which must be actively conserved. The low level of knowledge about the biology and ecology of this species is surprising, as well as the lack of basic information and monitoring of population size and trends.

Recommended measures must include the increase in research and the implementation of a population, disease, and genetic monitoring program. In addition, studies should be implemented to determine the effects of climate change, habitat change and hunting, as well as improvement in the protection against poaching. The establishment of a global hunting plan for all regional reserves and private hunting areas, and the establishment of a habitat management strategy considering grazing management, fire prevention, habitat restoration, preservation of most relevant habitats, and improvement of corridors are also priorities for the conservation and management of this endemic and highly range limited species (Ballesteros 2018, Ballesteros and Alves 2022).