Updated distribution of the elusive Roach’s mouse-tailed dormouse, Myomimus roachi Bate, 1937 (Mammalia: Rodentia: Gliridae) in Bulgaria

Myomimus roachi is one of the rarest and least studied mammals of the Western Palearctic. It is rare and sparsely distributed in the Southeastern Balkans and Western Anatolia. After its initial finding in 1959, the species was recorded only sporadically. All available data for the species distribution in Bulgaria are summarised and three new country records are reported, which all together increases the number of squares on the 10×10 km grid where the species has been recorded to 24. The current species habitats and threats are discussed.


Introduction
In Europe, five species of dormice are found. The rarest, the Roach's mouse-tailed dormouse (Myomimus roachi), occurs only in the Southeastern Balkans and in several isolated localities in Western Anatolia. It is one of the rarest and least known mammal species in the Western Palearctic (Kryštufek, 2008). Peshev et al. (1960) reported the mouse-tailed dormouse as a new member for the European fauna under the name M. personatus subsp. n. on the base of several specimens caught in Southeastern Bulgaria. Thereafter the species was found in the neighbouring Turkish Thrace and along the Western Anatolian coastline (Mursaloğlu, 1973;Kurtunur, 1975). Unlike the rest of the European dormice, the mouse-tailed dormouse avoids forest habitats. It has been found in vineyards, on the edge of maize and cereal fields and in arable lands with sparse old trees (oak, peer and walnut trees;Peshev et al., 1960;Kryštufek & Vohralík, 2005).
Bulgarian zoologists had caught the mouse-tailed dormouse predominantly on the ground surface (at that time snap traps were set only on the ground) and supposed that it was ground dwelling similar to its relative living in the Kopet Dag Mountain in Turkmenistan (Peshev et al., 1960 in Turkish Thrace the species was captured mainly on trees (Kurtonur & Özkan, 1990).
The Roach's mouse-tailed dormouse is a protected species (Annexes 2 and 3 of the Bulgarian Biological Diversity Act; VU in the Bulgarian Red Data Book (Popov, 2015); Annex 2 of Council Directive 92/43/ EEC or the Habitats Directive). The latest data for its distribution are summarised by Milchev & Georgiev (2012). Its biology and ecology are still poorly studied and generally unknown, no specific research has been done on the species in Bulgaria. The species is occasionally recorded during faunistic surveys; the most recent records come from studies on the diet of owls. So far, 36 dormice have been caught and 20 have been found in the diet of owls.

Material and methods
The bulk of data were collected in 2011-2012 during the project for mapping species within Natura 2000 network. Within this project, all known locations until 2010 have been checked by live-trapping: Sherman and Longworth traps (baited with peanut butter, apple, sunflower seeds) were set in suitable habitats. Traps were set on the ground surface and on some old trees: oaks (Quercus sp.), walnut trees (Juglans regia) and pear trees (Pyrus communis) at a height of 1.5-2 m. About 2000 trap-nights were realised. As an addition-al method for species detection, pellets from the barn owl (Tyto alba) from 17 localities and the little owl (Athene noctua) from two localities were collected. Pellets were drained and after that carefully cleaned; bones, skulls and jaws were separated and used for determination of mammals. The minimum number of individuals (MNI) was identified by the maximum count of fragments identified from the left and right mandibula, the maxilla or separate teeth. A total of 21 species were identified from 4400 small mammals in the diet of Tyto alba and 13 in Athene noctua. Livetrapping was also done in the summers of 2016 and 2017.
The study area encompassed the territory of Southeastern Bulgaria and the species distribution is presented using squares of the 10×10 km Military Grid Reference System grid (MGRS). We combined all previously unpublished observations and georeferenced published data into a GIS database, to update the current known distribution of the Roach's mousetailed dormouse.

Results
The species was not caught in traps during the 2011-2012 field seasons, despite the efforts (more than 2000 trap-nights). However, it was found in the barn owl pellets. Remains from M. roachi have been found in Generalovo and Izvorovo villages (Popov & Nedyalkov, 2013). At both locations, M. roachi was presented by a single specimen found among 151 (0.7%) and 356 (0.3%) prey items of small mammals, respectively. The mouse-tailed dormouse represented a negligible part of the diet of T. alba -0.045% (from 4400 prey items) in Southeastern Bulgaria, which was close to the previously reported proportions (Milchev & Georgiev, 2012). Our findings confirmed the presence of the species in the surroundings of Izvorovo Village, found previously from the region in the remains from the diet of the barn owl (materials of B. Milchev, in Peshev et al., 2004). We present two new localities where the species was recorded: Generalovo Village and MG33 in the Sakar Mountain. The current species distribution is presented on Fig. 1 on the basis of our and previously published data (Heinrich, 1936;Peshev et al., 1960;Markov, 1964;Angermann, 1966;Peshev & Angelova, 1967;Peshev & Spassov, 1985;Peshev at al., 2004;Georgiev, 2004;Milchev & Georgiev, 2012;Nedyalkov, 2013). Altogether, the species was found in 24 MGRS squares (10×10 km) in Southeastern Bulgaria.

Discussions
Previous studies have reported that the species is ground-dwelling; it has been caught mainly on the ground surface and, thus, resembles its relative from the Kopet Dag Mountain -M. personatus, the only other known species at that time (Peshev et al., 1960). Habitats in Bulgaria are quite similar with these in Turkish Thrace (Kryštufek & Vohralík, 2005).
Our data from radio-tracked survey on three mouse-tailed dormice (two female and one male), conducted in Turkish Thrace, have revealed that M. roachi spends much of its time on trees and lives in tree-holes and cavities at 1.5-2 m height, but also crosses wide open areas (150-200 m). It probably spends some time searching for fruits or insects (grasshoppers, crickets) on the ground (N. Nedyalkov, A. Staneva, personal data). In captivity, the species eats willingly insects and different fruits (Buruldağ & Kurtonur, 2001).
The species habitat has been under anthropogenic pressure for a long time, mainly due to forestry activities: planting and replacing the native habitats -woods of mainly Quercus-Carpinus and the semi-open habitats with shrubs and trees, with alien or atypical species such as the black pine (Pinus nigra), black locust (Robinia pseudoacacia), Atlas cedar (Cedrus atlantica). According to the national forestry database, there are multiple plantations at different stages (2-50 years Updated distribution of the elusive Roach's mouse-tailed dormouse, Myomimus roachi Bate, 1937… old) within the range of M. roachi (886 071.8 ha), with only the black pine covering 37.5% of this territory.
In the last few years, the species faces a new threat -a new practice for maintaining pastures has appeared in the region of Sakar Mountain and Dervent hills. In order to get subsidies for open pastures, the farmers use heavy-duty shredders to completely remove shrubs and trees. This practice not only changes the habitats through removing the hedgerows and fruit trees, but directly kills and exposes for future depredation other animals, such as tortoises (Testudo sp.), hedgehogs (Erinaceus roumanicus), hares (Lepus europaeus). In addition, fires are common events during the autumn drought and every year they destroy big part from the suitable for the dormouse habitats. Haas (1959) suggested that the mouse-tailed dormouse has vanished from the Middle East in the near past because of habitat changes -loss of fruit trees (Zizyphus sp.) as a result of intensive human cultivation. The species was quite common and used to be the predominant glirid during the Middle and Late Pleistocene but disappeared suddenly during the Late Bronze Age (Tchernov, 1975).
According to the last mapping project conducted in Bulgaria, the mouse-tailed dormouse is listed for 21 sites from Natura 2000 network, but still 50% from the known records lie outside the frame of Natura 2000. Its national population is estimated at 2226 adult individuals (Popov & Nedyalkov, 2013), but one should take it with a grain of salt. This estimation is made based on scarce population data and suitable habitats.
Bulgaria is the only country in the EU responsible to protect this species, but still not a single active conservation or monitoring project on the species has been launched. A big gap exists in our knowledge (for its biology and ecology) about this species, compared to the rest of the European dormice. There is need for urgent conservation efforts preventing further habitat degradation. A monitoring scheme should be launched as soon as possible.