Vacuum activity

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Vacuum activities (or vacuum behaviours) are innate, fixed action patterns of animal behaviour that are performed in the absence of the external stimuli (releaser) that normally elicit them.[1] This type of abnormal behaviour shows that a key stimulus is not always needed to produce an activity.[2] Vacuum activities can be difficult to identify because it is necessary to determine whether any stimulus triggered the behaviour.


From Latin vacuum (an empty space, void) noun use of neuter of vacuus (empty) related to vacare (be empty).


The term was first established by the ethologist Konrad Lorenz in the 1930s after observations of a hand-raised starling.[3] 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."[4]


Wild raccoons often appear to 'wash' their food which may be expressed as a vacuum activity by captive raccoons in the absence of water.

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.[5]

Lorenz observed that a starling bird snapped at the air when flying as if it were catching insects though there were no real insects there.[6]

Weaver birds go through complicated nest building behaviour when there is no nest building material present.[7]

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 behaviour is disputed). Captive raccoons sometimes perform these actions of 'washing' their food by rubbing it between their paws, even when there is no water available. This is most likely a vacuum activity based on foraging behaviour at shorelines.[8]

One vacuum activity that has been studied is 'tongue-rolling' by calves. 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 colour instead of the pale colour 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.."[4]

A similar vacuum activity to tongue rolling is 'vacuum chewing' by pigs. In this behaviour, pigs perform all the activities associated with chewing but with no substrate in their mouth. This abnormal behaviour can represent 52–80% of all stereotyped behaviours.[9]

Sham dustbathing (sometimes referred to as "vacuum dustbathing") is a behaviour performed by some birds when kept in cages with little or no access to litter. During sham dustbathing, the birds perform all the elements of normal dust bathing, but in the complete absence of any substrate.[10][11][12] This behaviour often has all the activities and temporal patterns of normal dustbathing, i.e. the bird initially scratches and bill-rakes at the ground, then erects her feathers and squats. Once lying down, the behaviour contains four main elements: vertical wing-shaking, head rubbing, bill-raking and scratching with one leg. However, hens "dustbathing" on wire floors commonly perform this close to the feed trough where they can peck and bill-rake in the food.[13] Because it seems the birds appear to treat the feed as a dustbathing substrate, the term "sham dustbathing" is more appropriate.

See also[edit]


  1. ^ Russell A. Dewey, PhD. Psychology: An Introduction. Chapter 8: Vacuum, Displacement, and Redirected Activities.
  2. ^ University of Plymouth: Department of Psychology. Lorenz Hydraulic Model of Motivation.
  3. ^ Lynne D. Houck; Lee C. Drickamer. 1996. Foundations of animal behavior: classic papers with commentaries. Animal Behavior Society.
  4. ^ a b Fraser, D. (2008). Understanding Animal Welfare: The Science in its Cultural Context. Wiley-Blackwell.[1]
  5. ^ Mazur, James (November 2016). Learning and Behaviour (8 ed.). Routledge. p. 23. ISBN 1138689947. Retrieved October 1, 2017.
  6. ^ Lorenz, K. (1981-09-23). The Foundations of Ethology. Springer Science & Business Media. ISBN 9783211816233.
  7. ^ Edward M. Barrows (2000-12-28). Animal Behavior Desk Reference: A Dictionary of Animal Behavior, Ecology, and Evolution, Second Edition. CRC Press. pp. 4–. ISBN 978-1-4200-3947-4.
  8. ^ "Raccoon behaviour". Retrieved August 19, 2012.
  9. ^ Robert, S; Bergeron, R; Farmer, C; Meunier-Salaün, M.C (2002). "Does the number of daily meals affect feeding motivation and behaviour of gilts fed high-fibre diets?". Applied Animal Behaviour Science. 76 (2): 105–117. doi:10.1016/S0168-1591(02)00003-5. ISSN 0168-1591.
  10. ^ Olsson, I.Anna S; Keeling, Linda J; Duncan, Ian J.H (2002). "Why do hens sham dustbathe when they have litter?". Applied Animal Behaviour Science. 76 (1): 53–64. doi:10.1016/S0168-1591(01)00181-2. ISSN 0168-1591.
  11. ^ Merrill, R.J.N., Cooper, J.J., Albentosa M.J. and Nicol, C.J., 2006. The preferences of laying hens for perforated Astroturf over conventional wire as a dustbathing substrate in furnished cages. Animal Welfare, 15:173–178
  12. ^ van Liere, D.W., 1992. The significance of fowls' bathing in dust. Animal Welfare, 1:187–202
  13. ^ Lindberg, A.C.; Nicol, C.J. (1997). "Dustbathing in modified battery cages: Is sham dustbathing an adequate substitute?". Applied Animal Behaviour Science. 55 (1–2): 113–128. doi:10.1016/S0168-1591(97)00030-0. ISSN 0168-1591.

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