Abnormal Behavior Definitions

Abnormal behavior has been observed in a wide variety of primate species housed in zoos, laboratories and sanctuaries. Behaviors can be considered abnormal if they are qualitatively different (i.e., occur in captivity but not typically in the natural setting) or quantitatively different (i.e., occur significantly more or significantly less than what is observed in the natural setting). Although abnormal behavior does not generally cause an animal harm, it can be an indicator of suboptimal environments, either past or present. Therefore, abnormal behavior is often used as a measure of wellbeing in captive nonhuman primates.

Establishing common definitions is a critical step in the standardization of terminology and assessment tools. This standardization is necessary for cross-center collaborative research, not only for attaining inter-observer reliability in data collection, but also to identify study subjects when employing inclusion criteria that focus on particular behaviors. This research will guide continued refinement of practices used to minimize the development and optimize the treatment of abnormal behavior.

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Abnormal Behavior Ethogram

Atypical posture: Holding a seemingly uncomfortable or contorted position.

Bob: rapid and repetitive up and down motion of the body on flexed limbs; animal does not leave the cage surface. Not accompanied by aggressive behavior.

Bounce: repetitively using one’s hind legs or all four limbs to push oneself off the cage surface. Not accompanied by aggressive behavior. 

Coprophagy: manipulating feces in the mouth; may include ingestion.

Feces paint: smearing and/or rubbing feces on a surface.

Flip: repeated forward or backward full-body somersaults.

Floating limb: An arm or leg rises into the air and may or may not contact the body (e.g., gently stroking the body). The action appears to be nonvolitional; the animal may interact with the limb as if it is not part of the body. This behavior may co-occur with self-biting.  

Hair pluck: removal of hair from one’s own body by pulling with teeth or hands, often seen with a quick jerking motion that is distinct from self-grooming. Hair may or may not be ingested.

Head banging: repetitively and forcefully hitting the head against an object or surface.

Head toss: repetitively moving head side to side, or in a circular manner.

Other stereotypical locomotion: idiosyncratic, repetitive whole-body movements that do not meet the criteria for other behaviors defined here.

Other repetitive self-directed behavior: pulling or chewing on tongue or cheek pouch; pulling and tenting skin; self- stroking outside the context of floating limb. 

Pace (aka stereotypic locomotion): repetitive locomotion following the same path; for example, walking back and forth on the ground, around the enclosure, or back and forth across bars.

Periorbital contact (saluting or eye poking): Animal holding hand, digit, and/or object against/near their eyebrow or eye.

Regurgitation and reingestion: backward flow of already swallowed food; the material may be retained in the mouth or deposited on a surface and reingested. May include the animal smearing the regurgitated food on a cage surface. 

Repetitive licking: Prolonged or repetitive contact of the tongue with a surface or object not involving food ingestion.

Rock: Any repetitive motion of the body from a stationary position. Animal remains sitting or standing, while the upper torso sways back and forth.

Self-bite: Closing the teeth on the animal’s own body (typically a limb). May be rapid and with force, or slow and “methodical.” May or may not result in wounding/injury.

Self-clasp: Clutching one’s own body with hands, feet, or full limbs in an embrace.

Self-injurious behavior (SIB): Any behavior any behavior that causes or could cause trauma to itself, such as bruising, lesions, lacerations, or punctures.

Self-oral (self-suck): sucking a part of one’s own body (e.g., digits, etc.).

Self-slap: Forcibly striking oneself with the hands or feet. May be repetitive.

Spin: repetitive circling of body around a pivot point.

Urophagy: Licking or ingesting urine.

Withdrawn: slumped or hunched body posture, often accompanied by dull eyes, and relatively unresponsive to environmental stimuli to which other monkeys are or typically would be attending.

Note: repetitive = a minimum of two to three times, depending on the current facility criteria.

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Abnormal Behavior Publications

Jacobson SL, Ross SR, Bloomsmith MA.
Characterizing abnormal behavior in a large population of zoo-housed chimpanzees: prevalence and potential influencing factors.
PeerJ 2016 08; 4(): e2225.

Lutz CK, Williams PC, Sharp RM.
Abnormal behavior and associated risk factors in captive baboons (Papio hamadryas spp.).
Am. J. Primatol. 2014 Apr; 76(4): 355-61.

Lutz CK.
Stereotypic behavior in nonhuman primates as a model for the human condition.
ILAR J 2014 09; 55(2): 284-96.

Martin AL, Bloomsmith MA, Kelley ME, Marr MJ, Maple TL.
Functional analysis and treatment of human-directed undesirable behavior exhibited by a captive chimpanzee.
J Appl Behav Anal 2011 05; 44(1): 139-43.

Nevill CH, Lutz CK.
The Effect of a Feeding Schedule Change and the Provision of Forage Material on Hair Eating in a Group of Captive Baboons (Papio hamadryas sp.).
J Appl Anim Welf Sci 2015 09; 18(4): 319-31.

Pomerantz O, Meiri S, Terkel J.
Socio-ecological factors correlate with levels of stereotypic behavior in zoo-housed primates.
Behav. Processes 2013 Sep; 98(): 85-91.

Pomerantz O, Paukner A, Terkel J.
Some stereotypic behaviors in rhesus macaques (Macaca mulatta) are correlated with both perseveration and the ability to cope with acute stressors.
Behav. Brain Res. 2012 Apr; 230(1): 274-80.

Pomerantz O, Terkel J, Suomi SJ, Paukner A.
Stereotypic head twirls, but not pacing, are related to a 'pessimistic'-like judgment bias among captive tufted capuchins (Cebus apella).
Anim Cogn 2012 Jul; 15(4): 689-98.

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