Who's the leader of the club that's made for you and me?

According to this PLoS Biology paper by Timothy Holy and Zhongsheng Guo, mice can sing.

Previously it was shown that male mice, when they encounter female mice or their pheromones, emit ultrasonic vocalizations with frequencies ranging over 30110 kHz. Here, we show that these vocalizations have the characteristics of song, consisting of several different syllable types, whose temporal sequencing includes the utterance of repeated phrases. Individual males produce songs with characteristic syllabic and temporal structure. This study provides a quantitative initial description of male mouse songs, and opens the possibility of studying song production and perception in an established genetic model organism (Holy and Guo 2005:e386).

The songs are ultrasonic, but share characteristics of organization with certain bird songs:

The richness and complexity of mouse song appear to approach that of many songbirds. For example, in the zebra finch, a widely used model organism for studying song production, individuals have a number (37) of syllable types [25,33] similar to the number of common types we find in mice (Table 1). There are other species, for example, canaries, whose vocal repertoire would appear to exceed that of mice [34]. Both mice (see Figure 6) and birds [25,33] exhibit regular temporal structure in their songs, including the production of repeated themes with sharp transitions between syllable types. However, mice also exhibit more gradual changes in syllable structure (see Figure 1). Overall, the tendency to repeat a syllable, with sharp transitions between types, appears to be stronger in some birds [34] and whales [3] than in mice. However, in birds these sharp transitions are a feature of the adult "crystallized" song; juvenile or isolation-reared birds are more experimental and less predictable in terms of the temporal structure of their song [33,35]. Indeed, our pitch-shifted recordings of mouse song sound similar to the early "plastic" song of species such as swamp sparrows (Audio S5). For this reason, any comparison between birds and mice should consider the development of mouse song over the lifetime of the animal. Such a study has been undertaken for properties like mean pitch and cadence over the first 2 wk of life [12], but is lacking for the more complex features that compose song (ibid.).

And I find this suggestion really interesting:

Because mouse songs are ultrasonic and therefore inaudible to human ears, it is worth noting that laboratory domestication has probably not acted to preserve the full richness of mouse song through generations inbreeding. One study documented considerable variability in the amount of vocalization by different laboratory strains [36]. In contrast, domesticated bird populations have been subject to song selection, and indeed sub-strains such as the Waterschlager canary have been bred for particular vocal qualities. It therefore seems possible that wild mice might exhibit considerably greater diversity and/or more complex structure in their songs. Future comparisons between the songs of mice and birds may benefit from using wild mice (ibid.).

Mouse song is a previously unobserved aspect of biology suddenly discovered after decades of selection that ignored it completely. Different laboratory strains (that differ both because of drift and because they were selected for different things) potentially have different song capabilities. I wonder if all the good singers are related? Or if mice bred for delayed mating still sing?

Next probable step: do FoxP2 knockout mice sing?

UPDATE (11/2/05): I love it when answers fall from the e-mail tree! See second post for the answer to the final question.


Holy TE, Guo Z. 2005. Ultrasonic songs of male mice. PLoS Biol 3:e386. Full text (free)