Hearing in Glires: Domestic rabbit, cotton rat, feral house mouse, and kangaroo rat

ß Behavioral audiograms were determined for four species of Glires: one Iagomorph (domestic rabbit, Oryctolagus cuniculus) and three feral rodents (cotton rat, Sigmodon hispidus; house mouse, Mus rnuseulus; and kangaroo rat, Dipodomys rnerrlarni). Considerable variation in hearing ability was found among the four species with low-frequency hearing limits ranging over 5-1/2 octaves from 50 (kangaroo rat) to 2300 Hz (fetal mouse) and high-frequency hearing limits ranging from 49 (rabbit) to 90 kHz (fetal mouse). Comparison of the ebaracteristies of each audiogram with the audiograms of other animals of the same Order, Cohort, and Class provide further evidence for the validity of two relationships: (I) interaural distance is strongly and inversely correlated with high-frequency hearing ability, and (2) good high-frequency hearing is apparently incompatible with good low-frequency hearing in most, if not all, land mammals. Furthermore, it is shown that cotton rats and ferai micc passess the ability to perform frequency discriminations even at very high frequencies, indicating that there is probably no difference about the way in which they perceive high and lowfrequency sounds. Finally, it is shown that kangaroo rats are not unusual in their ability to localize brief sounds, indicating that these animals have not compromised this ability in their acquistion of their unusual low-frequency sensitivity.