Vacuum Activity

Awkward Cell-Thumber by Elliot Thoburn

Vacuum activities are innate, fixed action patterns of animal behavior that are performed in the absence of the external stimuli (releaser) that normally elicit them. This type of abnormal behavior shows that a key stimulus is not always needed to produce an activity. Vacuum activities can be difficult to identify because it is necessary to determine whether any stimulus triggered the behavior.

For example, squirrels that have lived in metal cages without bedding all their lives do all the actions that a wild squirrel does when burying a nut. It scratches at the metal floor as if digging a hole, it acts as if it were taking a nut to the place where it scratched though there is no nut, then it pats the metal floor as if covering an imaginary buried nut.

The term was first established by Austrian zoologist Konrad Lorenz in the 1930s after observations of a hand-raised starling. In 1937 Lorenz wrote: ‘With head and eyes the bird made a motion as though following a flying insect with its gaze; its posture tautened; it took off, snapped, returned to its perch, and with its bill performed the sideways lashing, tossing motions with which many insectivorous birds slay their prey against whatever they happen to be sitting upon. Then the starling swallowed several times, whereupon its closely laid plumage loosened up somewhat, and there often ensued a quivering reflex, exactly as it does after real satiation.’

Wild raccoons often investigate their food by rubbing it between their paws while holding the food underwater, giving the appearance of ‘washing’ the food (although the exact motivation for this behavior is disputed). Captive raccoons sometimes perform these actions even when there is no water available. This is most likely a vacuum activity based on foraging behavior at shorelines. Sham dustbathing (sometimes referred to as ‘vacuum dustbathing’) is a behavior performed by some birds when kept in cages with little or no access to litter. The birds perform all the elements of normal dust bathing, but in the complete absence of any substrate. Weaver birds go through complicated nest building behavior when there is no nest building material present.

Calves raised for ‘white’ veal are generally fed a milk-like diet from birth until they are slaughtered at about four months of age. The calves are prevented from consuming roughage such as grass or hay partly because the iron contained in such plant-based food would cause their muscles to assume a normal reddish color instead of the pale color that purchasers of this product demand. The diet, however, is unnatural because calves would normally start to forage and ruminate from about two weeks of age. When limited to a milky diet, some calves will spend hours per day in what appears to be ‘vacuum grazing.’ They extend the tongue out of the mouth and curl it to the side in what appears to be the action that cattle use to grasp a sward of grass and pull it into the mouth, but the calves do this simply in the air, without the tongue contacting any physical object..’

2 Comments to “Vacuum Activity”

  1. That was incredibly interesting. I wonder if humans have any vacuum behaviors? What would they be? Would they be something vestigial, left over from earlier incarnations of man? Just thinking out loud…

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