Family Gliridae
dormice and hazel mice

The family Gliridae contains 28 species in 9 genera. It can be divided into 3 subfamilies: Graphiurinae (Graphiurus); Leithiinae (Chaetocauda, Dryomys, Eliomys, Muscardinus, Myomimus, and Selevinia); and Glirinae (Glirulus and Glis) (Wilson and Reeder 2005).

The family Gliridae is smaller than it was in the past. More than 30 glirid genera have become extinct since the Eocene (Daams and De Bruijn 1995). (Daams and De Bruijn, 1995; Wilson and Reeder, 2005)

Gliridae is an Old World family. Its members are found in sub-saharan Africa, in Europe north to southern Scandinavia, and in Asia east to southern China and Japan (Nowak 1999; Vaughan et al. 2000). (Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000)

Glirids live in temperate, subtropical, and tropical forests as well as shrubland, savannahs, the banks of rivers and streams, rocky outcrops, gardens, and agricultural areas (Klingener 1984; Nowak 1999; Vaughan et al. 2000). Species in the genus Selvinia inhabit desert scrub (Nowak 1999). (Klingener, 1984; Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000)

Gliridae has been known by two other family names, Myoxidae and Muscardinidae. Gliridae, or rather, "Glirini" (Muirhead, 1819), is the oldest of the three names, and originally included three genera, Dipus, Gerbillus, and Myoxus. The name was changed to Myoxidae in 1821 (Gray) and the family amended to include the genera Echimys and Myoxus. The name was changed back to Gliridae in G. G. Simpson's landmark classification of mammals in 1945.

In 1840, the genus Myoxus was divided into four subgenera, Graphiurus, Eliomys, Glis, and Muscardinus (Wagner, 1840). Later these names were recogized as distinct genera. In 1906, Thomas named the genera Glirulus (originally a species of Myoxus) and Dryomys (originally a subgenus of Eliomys). Myomimus and Chaetocauda were added to the family in 1924 and 1985, repectively (Ognev, 1924; Wang, 1985). The ninth genus, Selevinia, originally was considered part of Muridae (Belosludov and Bashanov 1939), and then was placed in its own family, Seleviniidae (Belosludov and Bashanov 1941). Having certain cranial characteristics in common with glirids, it was included in the family Gliridae by Holden in 1993. Its inclusion in the family is only tentative, however, due to the difficulty of attaining specimens of this rare species for molecular studies (Montgelard et al. 2003).

There has been some disagreement as to the number and composition of the subfamilies within Gliridae (Wahlert et al. 1993). In 1993, Wahlert et al. recognized the three currently accepted subfamilies based on cranial and dental morphology. The most recent taxonomic revision has been to move Muscardinus out of Glirinae and into Leithiinae (Montegelard et al. 2003). Wahlert's (1993) recognition of three subfamilies, and the move of Muscardinus, is supported by phylogenies based on the SPTBN (beta spectrin non-erythrocytic 1), TH (tyrosine hydroxylase), LCAT (lecithin cholesterol acyl transferase), and 12S rRNA genes (Montegelard et al. 2003).

The location of the family Gliridae within Rodentia has been a source of controversy over the years because glirids seem to have features in common with dipodoids and muroids and the sciuroid group (Wahlert et al. 1993). Ellerman (1940) placed the family within Muroidea. Other authors placed Gliridae in the superfamily Gliroidea and included Gliroidea in the Myomorpha along with Muroidea, Dipodoidea, and Geomyoidea (Wahlert 1978; Chaline and Mein 1979). Alternatively, glirids have been placed in a clade with sciurids and aplodontids (Meng 1990), or in their own, independent group (Parent 1980; Hartenberger 1985). Based on features of the cephalic arteries, Bugge (1974) concluded that glirids are more closely related to sciuromorphs than to myomorphs. Molecular phylogenies based on the CB1, IRBP, and RAG2 genes support the sister group relationship between glirids and sciuroid rodents (DeBry 2003). (Bashanov and Belosludov, 1939; Bashanov and Belosludov, 1941; Bugge, 1974; Chaline and Mein, 1979; DeBry, 2003; Ellerman, 1940; Gray, 1821; Hartenberger, 1985; Holden, 1993; Meng, 1990; Montgelard, Matthee, and Robinson, 2003; Muirhead, 1819; Ognev, 1924; Parent, 1980; Simpson, 1945; Storch, 1995; Thomas, 1906; Wagner, 1840; Wahlert, 1978; Wahlert, Sawitzke, and Holden, 1993; Wang, 1985; Wilson and Reeder, 2005)

Glirids are small to medium sized rodents, up to about 190 mm in head-body length. They resemble squirrels or chipmunks, with compact bodies and bushy tails (except members of the genera Selevinia and Myomimus, which have sparsely-furred tails). The limbs are relatively short; the feet are broad; and the toes are tipped with short, curved claws. Glirids have four functional digits on their forefeet and five on their hindfeet. Their bodies are covered with thick, soft fur. Some species have distinctive black facial markings. Most are good climbers, and arboreal species have well-developed toe pads. (Nowak, 1999)

Members of this family are myomorphous, but they differ somewhat from the typical myomorph arrangement of the masseter. Their skulls have an enlarged infraorbital foramen through which passes a slip of the medial masseter, as in other myomorphs, but the zygomatic plate is not as strongly developed as in most other members of the group. Nerves and blood vessels pass through this foramen as well as muscle; glirids lack the separate infraorbital foramen for the passage of nerves and blood vessels that is found in dipodids. The jugal of glirids is horizontal and does not meet the lacrimal. The mandibles are unusual in that the angular process is bent outwards, and in some genera it is perforated. Glirids are sciurognathus. (Klingener, 1984; Storch, 1995; Vaughan, Ryan, and Czaplewski, 2000)

The dental formula of glirids is 1/1, 0/0, 0-1/0-1, 3/3 = 16 or 20. The incisors are sharply pointed. Cheekteeth are brachydont, and their occlusal surfaces are made up of a series of cusps and basins or parallel enamel ridges. Selevinia (which is sometimes placed in its own family) has very small teeth that scarcely erupt from the gums. These have a very simple occlusal pattern. (Klingener, 1984; Storch, 1995; Vaughan, Ryan, and Czaplewski, 2000)

Wild edible dormice (Glis glis) have been reported to live up to 12 years. Such a long lifespan may be attributed to the fact that entire populations skip breeding in poor mast years, allowing them to put more energy into survival (Ruf et al. 2006). Lifespans of four years have been reported for other wild dormice (Dryomys nitedula and Muscardinus avellanarius). Eliomys quercinus and Graphiurus murinus each live 5 to 6 years in captivity (Carey and Judge 2002). (Carey and Judge, 2002; Ruf et al., 2006)

Most glirids are arboreal, though some Eliomys, Dryomys, Graphiurus, and Myomimus are terrestrial. They construct characteristic globular nests of plant matter in trees, shrubs, rock piles, the burrows of other animals, and sometimes even in human habitations (Nowak 1999). Activity patterns are nocturnal and crepuscular (Wahlert et al. 1993). Glirids living in temperate regions put on fat during the fall, then hibernate during inclement weather. Hibernation may last for the majority of the year; Muscardinus individuals, for example, have been reported to hibernate from August until May (Nowak 1999).

Some glirid species are solitary and territorial for part of the year. Territory sizes of 13.9 ha for males and 8.5 ha for females have been reported for Graphiurus. Glis mark their territories with secretions from glands. Though males may fight in the breeding season, several indivdiuals may congregate in the same nest to hibernate. Muscardinus live in small colonies and also hibernate in groups, with up to 11 individuals sharing a nest (Nowak 1999). (Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000; Wahlert, Sawitzke, and Holden, 1993)

These rodents have acute visual, auditory, olfactory, and tactile senses. They are known to emit shrieks, whistles, and chirping noises that may function in communication. Members of the genus Glis scent-mark their territories with glandular secretions (Nowak 1999). (Nowak, 1999)

Glirids are omnivores, feeding on fruit and nuts and also eating invertebrates, birds and their eggs, and sometimes other rodents. Selevinia feeds mostly on insects and spiders (Vaughan et al. 2000). Glirids that hibernate may store food over the winter and occasionally awake to consume it (Nowak 1999). (Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000)

Owls are the most frequent predators of glirids (Bouvier and Bayle 1989; Vvano and Turini 1996). When alarmed, glirids deliver a painful bite with their sharp incisors, they may also hiss, spit, and leap high into the air (Nowak 1999). Glirids have the ability to regenerate their tails if lost to predators (Vaughan et al. 2000). (Bouvier and Bayle, 1989; Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000; Vvano and Turini, 1996)

Glirids function as primary, secondary, and higher-level consumers in the ecosystem, because they eat both plants and animals (Nowak 1999; Vaughan et al. 2000). They are also prey for owls (Bouvier and Bayle 1989; Vvano and Turini 1996). (Bouvier and Bayle, 1989; Nowak, 1999; Vaughan, Ryan, and Czaplewski, 2000; Vvano and Turini, 1996)

These rodents may be detrimental to agriculture, raiding poultry yards and consuming crops such as plums, grapes, pears, and apples. They also sometimes make themselves a nuisance when they nest in houses (Nowak 1999). (Nowak, 1999)

Glis are trapped for their luxuriant fur as well as for their meat, which is considered a delicacy in parts of Europe (Nowak 1999). (Nowak, 1999)

Of the 29 glirid species, nine are listed as least concern, four are listed as lower risk, four are listed as vulnerable, and four: Chaetocauda sichuanensis, Glirulus japonicus, Myomimus setzeri, and Selevinia betpakdalaensis, are listed as endangered on the 2006 IUCN Red List. Not enough data is available to rank the remaining eight species. The most immediate threat to glirids is habitat destruction, though pesticide use and loss of genetic variation in isolated populations may also lead to declines (Nowak 1999). (IUCN, 2006; Nowak, 1999)