The sight of a mouse, pivoting on a hind leg, gyroscopically whirling around 416 times without stopping or reversing might reasonably lead the observer to conclude that he or the mouse was drunk. Yet sober scientists have watched a sober mouse perform this very feat. The whirler was a Japanese waltzing mouse. It whirled because of a physical defect, probably of its inner ear.
At Ann Arbor last week the University of Michigan's Zoologist Lee R. Dice announced to the Michigan Academy of Sciences his discovery that this ear defect is hereditary not only in the mice of Japan. He has found it in four strains of the common American deer mouse. Because this offers one of the few non-human instances in which abnormal behavior can be traced to a definite hereditary characteristic. Dr. Dice believes that further study of affected mice may help man to understand how he inherits nervous peculiarities.
The baby mouse waltzer begins to dance when it is one week old. Thereafter, think scientists, its life is a frantic quest for the balance which it cannot feel on a horizontal plane. Sometimes it whirls on a hind leg, sometimes runs in circles or figure-eights, always twitching, jerking, swaying its head. Occasionally an accomplished mouse varies the routine with a shuffling backstep. Sometimes the mice dance together, one spinning on a hind leg while another runs circles around it. They like to run on treadmills, through tunnels, over bridges, up inclines.
The Japanese species is several centuries old. Zoologists believe it a sport from the Central Asian Mus wagneri, which it resembles in size and structure. In Japan, where they were brought from China about the middle of the last century, dancing mice are common household pets.
The Japanese mouse is a tiny creature, one of the smallest of mammals. It is usually black-&-white spotted, with eyes that look black in daylight, ruby-colored at night when the fire-red pupils expand. It spends the hours from dusk to midnight dancing, sleeps till dawn. The impulse to dance may seize it any time during the day. Rest periods it passes sleeping, washing, sniffing, eating. Because of its exertions it has to eat & drink much oftener than an ordinary mouse. It is totally deaf.
Wild waltzing mice are rare. They seldom find another of their kind to mate with. They seem to be less hardy than normal mice. Waltzing mothers often tangle their babies so tightly in the nest material or in their own long tails that the mouselets suffocate or starve. Captivity and inbreeding are necessary to perpetuate the trait in whole families.
In Kansas City last week a cock robin, undeterred by shouts and lowerings of the shade, was slowly weakening as it passed its tenth day of attacking its own reflection in a windowpane.