||Motor Patterns of Defense||Page 14|
Unvoiced sounds made by expiration of the breath are produced by several muroid rodent species during defense. These have been called "voiceless snarlings" in L lemmus [Arvola et al, 1962], "fauchen" or spitting noises in Cri cricetus [Eibl-Eibesfeldt, 1953a], and hissing in R villossimus [Begg, 1975] and in R norvegicus [Hughes et al, 1976; Barnett, 1969]. These sounds are usually reported in defense elicited by a predator or man, and less commonly in fights with conspecifics.
Teeth-chattering is frequent during defense in about half of the well-studied species of muroid rodents. It has been reported in response to both predator and conspecific attack in L lemmus [Arvola et al, 1962], Cr gambianus [Ewer, 1967], R rattus [Ewer, 1971], and Cri cricetus [Eibl-Eiblesfeldt, 1953a]. As a defensive response to con specific attack, it has also been reported in D groenlandicus [Brooks and Banks, 1973], Ondatra zibethicus [Steiniger, 1976], Clethrionomys sp var [Johst, 1967], Ne floridana [Rainey, 1956], and Ne fuscipes [Linsdale and Tevis, 1951, p 240]. In many of these species, as noted earlier, teeth-chattering also occurs during offense, ie, it is an ambivalent motor pattern. In Ne fuscipes, however, it occurs only during defense, while in some species of Rattus it occurs only during offense.
Three other types of nonvocal defensive noises have been reported in a few muroid rodent species: Pattering of the forefeet, thumping of the hind feet, and rattling of the tail. These usually occur at a low threshold in response to stimuli associated with a predator and, as such, they may serve as warning signals to conspecifics. Pattering of the forefeet has been reported only in a few species of Peromyscus (maniculatus, truei, and anderemicus) and is not even frequent in other Peromyscus sp var such as californicus or crinitus [Eisenberg, 1968]. It apparently does function as a warning signal, since related animals respond by freezing and erecting the ears [Eisenberg, 1962]. Thumping of the hind feet has been reported to accompany defense in T leucogaster [Choate, 1972], Ps obesus [Daly and Daly, 1975], Ne floridana [Rainey, 1956], Mer unguiculatus [Swanson, 1974], Mer persicus [Eibl-Eibesfeldt, 1951], and Rh opimus [Naumov, 1975]. Eibl-Eibesfeldt  has also reported similar motor patterns in M musculus, R norvegicus, Gerbillus sp var, and other species of Meriones. In Rh opimus, the motor pattern of hind-feet-thumping has been observed to serve as a warning to conspecifics [Naumov, 1975]. Tail-rattling has been reported as a defensive motor pattern in M musculus [Beilharz and Beilharz, 1975], Ond zibethicus [Steiniger, 1976], and Ne fuscipes [Linsdale and Tevis, 1951, p 234]. In the last named study, the tail-rattling has been observed to function as a warning signal to nearby conspecifics. The great variability of warning noises from one species to another is particularly evident in the genus Neotoma, in which the species floridana has been observed to use foot-thumping but not tail-rattling, while the species fuscipes has been observed to use tail-rattling but not foot-thumping as a warning signal [Kinsey, 1976].