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Species: Gorilla

Use: General Activity

Authors: C. Bennett, J. Fried, Dallas Zoo

Methods: Focal Sampling, scan sampling

Publications/Presentations: Compilation of Gorilla EthogramsLocomotion

Walk: Individual travels from one location to another by using two, three, or four limbs to propel the body. Two or three limbs are always on the ground at one time.

Walk quadrupedal: The animal uses all four limbs to travel forwards, backwards, or to the side. Leg movement is transverse (i.e., left forefoot and right hindfoot moving together, then right forefoot and left hindfoot moving together). Gorillas primarily knucklewalk, but occasionally walk on the sides of closed fists.

Walk bipedal: in this form of locomotion, the torso is perpendicular to the ground. Travel is executed by using hind limbs alone. Legs are extended and support the body. Forward motion of the legs comes more from a forward and backward rocking of the pelvis rather than rotational movements in the hip joints. Arms are usually held close to the side or are wrapped around the torso. Sometimes, individuals walk bipedally for short distances while holding onto a structure (i.e., cage bars, bench, door frame edge, ropes, trees, vines) or while carrying object(s).

Run: Three gaits can be observed: transverse quadrupedal, lateral quadrupedal (gallop) and bipedal. Regardless of the gait, none, only one, or tow limbs will be on the ground at a time. Bipedal run is achieved by slightly elevating the torso and lifting the arms during a transverse run. This usually occurs within aggressive display sequences or bouts of play behavior.

Slide: Occurs at end of a run. The animal remains quadrupedal but stops the running motion while keeping the limbs rigid. The body might be turned at an angle to the direction of travel. A slide may be terminated by the presence of cage bars, wall, limbs etc.

Arm over arm swing: An animal grasps an overhead structure with its hands. The arms are nearly fully or fully extended. The animal releases one hand and pivots the body forward from the still grasping hand while extending the other hand to grasp a structure. It then pivots the body forward. Swinging movements are slow and deliberate. Reminiscent of brachiation.

Skip: Not observed in Dallas animals.

Swing: Not observed in Dallas animals.

Circle: Not observed in Dallas animals.

Scoot: Two forms of scoot have been observed, and both occur with the animal in the squat position. One is a wobble like movement, where the animal leans from side-to-side while swinging the elevated side of the body forward. This can be done with the arms crossed on the chest or resting on the knees, but the arms could be used to pull the animal along while it moves next to the cage bars or ropes. The second form is characterized by use of the arms in a crutch like manner. The arms are placed on the ground in front of the body. With the arms rigid and braced on the ground by tightly closed fists, the body is pivoted forward by swinging between the arms. Both modes of scoot are primarily used fro short distance travel, but individuals have been observed to travel up to twelve feet in this manner.

Climb: Gorillas are methodical climbers moving carefully and always having two limbs in contact with a structure at any one time. The type of structure being climbed appears to influence the specific climbing movements used. When climbing cage bars, wood ties, or trees, movement of the limbs is basically transverse quadrupedal (transverse limbs may move together or in series). When climbing up ropes or horizontal bars, an animal may grasp them with its forelimbs and partially swing its body up off of the ground until the hindlimbs can also grasp or lean on the structure, thereby assisting the forelimbs in pulling the body up.

Sit: Basically, sitting consists of: torso erect, not in contact with ground, resting platform, substrate, etc., buttock on ground, legs in front or to the side of the body. Several variations of sitting postures are regularly displayed:

Legs: Bent acutely at the knees, rotated outwards from the body (outer thighs are close to the ground), and crossed at the ankles or shins (aka: Indian style). The legs can also be extended forward and crossed at ankles, bent with knee(s) up and foot/feet flat on ground, legs extended and near parallel, or extended and split apart up to a 90 degree angle.

Arms/hands: Crossed on chest, crossed or lying in lap, gripping feet, resting on knee(s) or extended with knuckles resting on ground for additional support. Animals will frequently hold on to structure (i.e. ropes, cage bars, cross-ties) or rest limbs on it.

Torso: Upright almost perpendicular to the floor, angled acutely forward over legs at about a 45 degree angle or less to the floor, or leaning to the side supported by structure, object, or extended arm. Record as torso upright, torso hunched over, or back, side or arms supported.

Squat: In this posture, legs are acutely bent at the knees and thighs, with the feet under the body and heels tucked into the buttocks. Feet and legs bear the bulk of the weight and can be in front of the body or to the side. Buttock does not contact surface. A squat position is assumed when the animals defecate or urinate (see Elimination category). There are several variations of the squat position:

Legs: Knees are bent and can be tucked up in front of the chest or angled outwards until they form an almost straight line with the body.

Arms: Forearms or elbows are frequently resting on knees, thighs or holding onto a structure (i.e., cage bars), but may also be crossed on chest or extended to the ground for additional support.

Torso: Squatting animals will frequently have their backs upright against a structure (i.e., cage bars, walls, concrete posts). When supported by arms extended out, the torso may be bent at a 10 to 15 degree angle.

Perch: Animals assume a squat posture when they are off of the ground. The feet are used for grasping surfaces.

Legs/feet: Grasp structure with feet side-by-side or one in front of the other.

Arms/hands: Grasp same structure/object or nearby structure/object with hand(s) for additional support.

Lie: In this posture, the body is in a recumbent, prostrate position. The body can be dorsally, ventrally, or laterally recumbent. Variations within these positions include:

Ventral: Primarily the ventrum is on the resting surface. Variations of ventrum include-

Arm(s): May rest chin on forearm of hand

Legs: May be bent at knees and tucked under the body or hips may be rotated so both legs lay out to the side

Dorsal: Primarily the back is on the resting surface. Variations of dorsal include:

Arms/hands: Are frequently folded across the chest or are elevated with the elbows extended out and hands resting on the head. Occasionally, the arms are extended outwards and grasping a structure.

Legs/feet: May be crossed at ankles or knees, sometimes an ankle may rest on opposite knee. The feet may be gripping an object or could be propped up against a structure. Sometimes, legs may just stick up in the air at a 90 degree angle to the plane of body. Foot-foot and hand-foot grasping occurs frequently.

Lateral: Primarily the left or right side of the torso is on resting surface. Variations include:

Arms/hands: May be folded on chest, lying along length of body or one/both arm(s) may be bent up under head as ÒpillowÓ.

Legs/feet: Are usually bent at knees, pulled up towards the body, and laid on top of the other. The legs also can be crossed at knees or ankles. Foot-foot and hand-foot grasping occurs frequently.

Torso: The back may be against an object or unsupported.

Stand: Outstretched or extended arms and/or legs are in contact with a surface and bear body weight. Stand, like sit and lie, can take several forms.

Stand quadrupedally: All four limbs are extended, are in contact with a surface, and support the body weight. The torso is generally parallel to the ground. Animals will stand on knuckles or on closed fists; on flat feet with thumbs extended or on the side of the feet. Variations on the basic quadrupedal stance can be identified as threat behavior (see descriptions in agonistic behavior).

Stand bipedally: The torso is in an upright or nearly upright position (perpendicular to the ground). The legs support the body, are widely spaced, and bowed or slightly bent. The feet are turned out, and thumbs extended out from foot. There is no other support.

Stand supported: The animal is in a bipedal or monopedal position with the torso perpendicular or even parallel to the ground. The weight is supported by the legs, hands, or arms, which may be grasping or resting on some structure.

Survey

Visual: Animal stops an ongoing behavior or is engaged in no other behavior and orients head and eyes toward a specific direction or component of the environment. This orientation can be prolonged (greater than 2 sec).

Visual side glance: The animal repeatedly shifts its eyes to the side and focuses momentarily on components of the environment. The head is stationary and may be oriented away from the object(s) of scrutiny.

Inspect: Includes both tactile and olfactory components. The animal reaches out and touches an object with its knuckle(s) or forefingers. The digit(s) are then brought to the nose and apparently sniffed.

Olfactory: An animal brings the nose close to an object or the object near the nose and sniffs.

Gustatory: An animal licks an object, places it momentarily in the mouth or between the lips, or touches something then places fingers in the mouth.

Object manipulation

Object gather: An animal accumulates objects that are dispersed and brings them to a central location.

Object-dissemble: Involves a wide variety of actions where the hands, feet, and mouth, are used to rip, shred, twist apart, remove components, or peel an object (normally inanimate, but not necessarily).

Object hold: An animal is inactive/idle with an object resting in the hand, foot, mouth, or pressed against the body. No other manipulation is occurring.

Object carry: An animal uses its hands, mouth, legs, and/or feet to transport an object. Objects may also be carried by tucking them between the thigh and belly.

Object rigid manipulation: An animal uses an object to rattle, shake, bang, or pound.

Object use: Involves utilizing objects which are not permanent fixtures for a number of different purposes: use of an object as an extension if the body in order to attain an immediate goal (tool), to increase comfort (furniture, nest), as covering, as a weapon, etc.

Object varied or non-specific manipulation: This is a catch all category that includes touching, pushing, absently rocking, bending, lip rolling, etc.

Manipulate

Autogroom: Animal uses fingers and/or lips and teeth to manipulate and remove items from its fur.

Autopick: Animal uses fingers and/or lips to pick debris from its teeth, nails, nose, ears and eyes.

Probe anus: Animal uses fingers to poke at or rub its anal region.

Masturbate: Self-stimulation of genitalia.

Manual: Animal manipulates its genitals with its hands or feet.

Pelvic rub: Female backs up to an object and rubs anogenital area against it.

Haunch bounce: From a squatting position animal bounces up and down on haunches. Males may create a false vagina with hands and haunch bounce while directing the penis into the hands.

Autoinspect: Animal makes a close visual or olfactory examination of own body parts.

Comfort: Comfort movements consist of brief, transitory movements such as changes in posture; e.g., rolling over and changing orientation of limbs; and attempts to ease or relieve an uncomfortable situation; e.g., stretching, scratching, yawning, coughing, clearing the throat, etc.

Eliminate

Urinate: Expel urine. Animals assume a squat position with torso tipped forward and weight on its arms which are extended in front of the body.

Defecate: Expel feces. Position during defection is similar to that described for urinate. Animals may urinate and defecate at the same time.

Regurgitate: To eject part or all of the stomach contents through the mouth, usually in a series of involuntary spasms. However, gorillas seem to have a high degree of control over regurgitation.

Play: Lone play includes repetitive, exaggerated, disjointed, and seemingly nonpurposeful behavior. When alone, such behavior usually involves an inanimate object or consists of repetitive movements accompanied by a play face.

Object: Shake, bounce, hit, juggle item, rub, swing, toss in air. Movement is exaggerated. Water can be considered to be an object.

Peregration or locomotor play: Clap, rock, somersault, shake, twist, run, slap, pat, circle, lip flap.

Body oriented: Manipulate body part, exaggerated head and/or body rubbing, pulling of extremities etc.- chest beat.

Ingest: Includes a wide array of behavior associated with the location, procurement, processing, and consumption of items.

Forage: Manipulation of substrate or objects in the environment which results in obtaining food items (substrate is frequently edible itself). This includes the periodic transfer of food from hand/foot to mouth and travel of one or two steps between searches. Several foraging motions can be used. For example, animals may sweep a arm from side to side and move substrate with the back of the hand or pick up the substrate and place or throw it aside, or a substrate might be picked up and held while an animal forages through it. To pick up food items, animals will use a finger pinch (forefinger or middle finger and thumb or tip of forefinger or middle finger for small forage items). A variety of postures may also be assumed while an animal forages: tripedal with free arm foraging, sitting, squatting, or lying ventrally while resting on forearm(s) or elbow(s).

Food carry: Travel while holding food items. Food can be carried by mouth, hand, feet, in the crook of the arm, against the chest, against the stomach, or any combination of these methods. Animals walk bipedally (rarely), tripedally (most commonly), or quadrupedally. Animals will knuckle walk with food in their hands or will walk on the back of the hands/wrists while holding food. When climbing, animals will frequently carry food in their mouths. Animals may also scoot along for short distances while carrying food.

Food gather: See object gather.

Food process: Various manipulations of food items (provisions, browse, bedding) that give an animal access to an otherwise inaccessible edible or preferred portion. This might involve one or more of the following: stripping (usually length wise), peeling, shredding, breaking apart, husking, shelling, or shaking apart. Each action can be carried out with the teeth, hands, lips or feet, but usually occur in combination. Visual and olfactory inspection of food frequently occurs during processing. Individuals usually sit while food processing, but will also recline ventrally.

Food beg: The animals will extend arms and clap hands together several times or will clap hands together and then open hands palms upwards. Hands are held in a relaxed manner with fingers curled inwards. Knuckles on each hand are actually tapped gently together. If this does not get a response, the animals may rap on the bars of the doors. Grunt-like vocalizations may accompany begging. This behavior is usually directed towards a keeper.

Eat: Placement of food items in the mouth by hands, feet, or lips followed by chewing and swallowing. ÒEatÓ does not require that a substrate be manipulated in order to obtain food. Visual inspection, olfactory inspection, manipulation, and/or food processing may occur prior to and during eating.

Food may beÐregular provisions, browse or forage, or body waste (excrement, cerumen, nasal mucus, scabs, sweat, dead skin, etc.)

Individuals have also been observed to wipe sweat from their arm pits with their hands and then lick their hands.

Drink: Animals drink from fountains, pools, streams, or from areas where fluid had accumulated. Similar drinking postures are used by the Dallas individuals. From a quadruped stance, an animal either bends forward and places both hands against a wall, fountain edge, or on each side of the body; or crouches down with torso supported by all four bent limbs and ventrum close to the ground. The head is horizontal when drinking. The animals will lick up fluids or suck them directly into the mouth.

Regurgitate and reingest: expelling stomach contents through the mouth and then consuming the regurgitate.

Specify body position while regurgitating:

Tilt position: The legs are straight or slightly bent at the knees. Body is bent at the hips with the torso straight and angled downwards. Body weight is supported by one forearm, both forearms (parallel along the orientation of the body, parallel and running across the chest or crossed across the chest) or one or both arms can be resting with the palms flat on the ground and elbows pointing out to the sides or backwards along the body. The head is lower than the hips. Dallas gorillas will regurgitate onto a surface or into their mouths from this position. The gorillas will assume a tilt posture usually from a sitting or squatting stance. Several head bobs frequently occur prior to regurgitation.

Lie ventral: The animal reclines ventrally on the ground, resting on the forearms (which are held parallel across the chest). Head bobs usually precede regurgitation.

Quadrupedal stance: The animal assumes a quadrupedal stance with legs and arms bent to varying degrees, but the torso remains parallel to the ground. Vomitus is forcefully expelled from 1/3 to ý m (1.5 ft.) above the receiving surface.

Quick tilt: From a squat or sit position the animal rapidly tilts forward on its palms then quickly returns to the previous position (looks like a pushup from a sitting position). The gorilla might straighten its back legs a bit when tilting forward but bends them again when it returns to the sit/squat position. Regurgitation is usually into the mouth ands reingestion occurs while in the sit/squat position.

Headshake: From a sitting or squatting position the gorilla moves its head to one side and slightly upwards in a somewhat circular motion or quickly up and down. The mouth might open and then close quickly. The movement can be so slight that it may seem as if the gorilla is moving its head in order to relieve a crick in the neck. It may be mistaken for a comfort movement. The gorilla appears to regurgitate into the mouth; cheek bulging and chewing movement can be seen. Vomitus is usually retained in the mouth.

Methods of reingestion

Reingest with the hand: An animal will dip or run its fingers and whole hand into vomitus and then lick the material off. Usually, the material has a liquid consistency. An animal sometimes uses its hand to scoop and maintain vomitus in small puddle. If the vomitus is thick or chunky, the fingers and thumb, in a pincer motion, are used to pick up matter and transfer it to the mouth.

Reingest with the mouth: Use mouth, lips and tongue to suck, lick, or pick up vomitus.

Position for reingestion:

Squat on elbows: Feet are flat on the ground, the body is bent forward at the hips so that the ventrum is on the ground. The gorilla is resting on the forearm(s). Hand or mouth will be used to reingest from this position.

Sit/squat: Animal assumes a sit or squat posture (described elsewhere) after the quadrupedal. Quick tilt, or head shake regurgitation.

Lie ventral: Similar to the squat on elbows position but the feet are not flat on the ground but extended out from the body. The animal usually rests on the forearms.

Tilt position: This is the same posture as used during the regurgitation phase.

Stereotypic: Stereotypic behavior is characterized by excessive repetition of or lack of variation in vocalizations, movements, postures, or patterns of travel.

Stereotypic posture: Prolonged maintenance of an unusual or bizarre stance, placement of extremities, or attitude.

Stereotypic movement: Involves body or limb movements but not travel.

Head circle: A serried of 2-12 unidirectional head rotations which occur most frequently while in a quadrupedal stance with the head, neck, and shoulders oriented towards a corner of an enclosure. The head is only 1/3 to ý m from the wall. This behavior has been observed only in the younger silverbacked male.

Head swing: This motion is similar to head circles but the head hangs down and swings back and forth. The head does not make full rotations. It occurs mainly while sideways walking and occasionally while facing the wall or into a corner. This behavior has been observed only in the younger silverbacked male.

Rock: Legs are bent and the knees are near chest, arms are on knees or folded across chest. From this position, the animal sways from side to side (movements are no more than 5-10 cm to each side). This is usually done while the animalÕs back or side is against a vertical structure but has occurred while it is gripping the cage bars with its hands or while perched on a horizontal bar. Rocking occurs in association with finger sucking. This behavior has been observed only in the younger adult female.

Hand clap: Hands, with fingers curled in, are brought together rapidly several times. This behavior has been observed only in the younger adult female.

Stereotypic locomotion: Repetitive, unvarying, and seemingly meaningless pattern of travel.

Pace: Repetitious, patterned and usually unidirectional movement around the exhibit/habitat. The animal seldom makes more than two complete circles about an enclosure. Pacing speed is faster than the usual walking speed. This behavior is seen in the younger silverbacked male and in both adult females.

Stereotypic self-oriented: Excessive repetition of an unvarying form of self manipulation or self grooming.

Finger sucking: Animal will insert forefinger and/or middle finger of either hand completely into mouth. Seen frequently in association with rocking. Occurs while the animal is in a sitting, squatting, or perched position. Legs are bent up near chest, arms are on knees, or folded across chest. This behavior has been observed only in the younger adult female.

Belly scratching: Belly scratching consists of a rhythmic flexion of fingers or up and down movement of wrists so that the fingers are rubbed gently across the stomach region. Hands may alternate scratching, scratch in unison, or scratch singly. The animal will belly scratch while holding straw in the scratching hand.

The scratching posture is sitting with knees acutely bent and rotated outwards so the soles of feet are flat against each other or legs may be slightly extended with feet gripping cage bars. Seen only in the older adult female.

Stereotypic object use: Repetitive, unvarying, and seemingly useless manipulation of an object.

Stereotypic noises (Auditory): Repetitive, unvarying, and seemingly useless production of sound. This does not include the occasional production of unusual sounds or noise.

Motor boat sounds: Forcing air through tight lips makes a sound similar to a high pitched motor boat. Emissions are of short duration (< 1 sec) but occur in series (one bout had 35). Occurs primarily while the animal is in a resting/idle posture. This behavior has only been observed in the younger silverback male.

Unusual/idiosyncratic

Lip hang: The lower lip droops loosely down exposing gums and inner lips. This behavior occurs in a variety of contexts, such as after aggressive encounters, during resting periods, during foraging bouts, while locomoting, while manipulating objects, and when head circling or head swinging. This behavior has been observed only in younger silverbacked male who displays it frequently and incorporates it into many behavior patterns.

Reproductive/Sexual

Precopulatory: Sexual behavior which occurs prior to copulatory mounting.

Penile erection: There is no mounting. This is very difficult to observe.

Inspect genitalia: Close visual, tactile, or olfactory scrutiny of the genitalia or genital region of another.

Touch: An animal briefly touches, holds, fondles, or mouths the genitalia of another.

Olfactory/sniff: An animal leans over and presumably sniffs the genital region of another. Touching anotherÕs genitalia and then sniffing the finger/hand is included in this category.

Solicit: One animal engages in a variety of postures, gestures, or movements which have a high probability of eliciting sexual behavior from another.

Stare: Female stands motionless while intensely watching the male.

Extended arm invitation: Female reaches toward male with arm stretched and palm facing the male.

Head jerk: While staring at a male, a female intermittently tosses her head to one side. Her body appears relaxed and the lips are not compressed.

Present quadrupedal: Female stands on all limbs and orients her anogenital region directly towards another animal. She may slightly elevate her hindquarters or display a head jerk.

Back into: Female first presents and then walks backward into the male.

Open leg display: Female slides down past another while her legs are spread widely apart. This behavior occurs in a playful context.

Crouch: While in front of another, female bends low to the ground with her limbs pulled underneath her.

Ground object tap: While male is oriented toward a female, he repeatedly taps the substrate with the fingertips of both hands.

Haunch scoot: While squatting, a female uses her arms to propel herself towards the male.

Quad-bounce: While standing on all fours and facing another animal, a female bounces her hindquarters up and down. Similar to a haunch bounce, but done while animal is standing- may be a form of masturbation as well as solicitation.

Pronk: While standing quadrupedally and facing another animal, a female hops about in a jerky fashion. The hindquarters are slightly elevated.

Pronk-mount: A female pronks while grasping another animal around the waist.

Play present: A female presents in an Òapparently playful contextÓ. The angle of bend at the hips is greater than in the other ÒpresentÓ solicit. The female may rest on her forearms and occasionally look backwards (over her shoulder or between her legs) at the male.

Copulatory

Mount attempt: Male attempts to make genital contact with female (in any posture), but the attempt fails.

Mount: One animal positions itself on another such that their genitalia are in contact (can be same sexed), mount is of short duration with no pelvic thrust observed. Orientation of mount can be dorso-ventral, ventro-ventral, or ventro-lateral.

Copulation: One animal mounts another in any orientation (D/V, V/V, L/V). Mounting is followed by about 30 to 45 sec of position adjustments before pelvic thrusting begins. During copulation the female exhibits compressed lips and the male exhibits pursed lips. The female will occasionally look over her shoulder at the male, and sometimes wave her head side to side with her eyes closed and may emit copulatory whimpers. It is very difficult to observe intromission.

Reach around: During copulation, while in the D/V position, the female twists shoulders and neck to look at the male, and reaches back and touches the male on the head.

Copulatory whimpers

Pursed/compressed lips

Postcopulatory

Touch genitalia: Visual and tactile inspection of an individualÕs own genitalia following copulation.

Vocalization: After copulation.

Play: Repetitive, exaggerated, disjointed, and seemingly nonpurposeful behavior involving two or more individuals. This behavior is accompanied by the Òplay faceÓ which is characterized by an open mouth which partially exposes the teeth, but the lips are relaxed at the edges. Social play may be accompanied by soft chuckling or a throaty grumbling. Both gentle and aggressive components may be observed, so it is easily confused with aggression (which is generally much louder).

Contact/direct play: Two or more individuals are engaged in play involving almost continuous contact. This includes such interactive acts as:

Stand/climb on, wrestle, slap/beat, tickle, poke, grab, kick, carry, ambush, tag, push/nudge, swat, tap on another, object tug/grab, mouth.

No contact/indirect play: Two or more individuals are involved in play that does not involve direct contact. This could include such acts as:

Chase, throw at, ground/water slap, object wave/shake/brush on ground, arm shake, chest beat, body slap (own), circle.

Solicit play: One animal engages in a series of postures, movements, or gestures (runaway, swagger, chest beat) which has a high probability of eliciting play from another.

Parallel play: Two animals engage in lone or object play within proximate distance of one another.

Groom

Allogroom: One animal manipulates the fur, extremity, or orifice of another. During a grooming episode, the groomer often looks intently at the portion of the body which is being manipulated. Grooming may include both manual and oral components.

Manual: Individuals use the fingers and whole hand to manipulate and remove materials.

Oral: Use of mouth and lips to manipulate and/or remove materials.

Mutual groom: Same as above, except the two animals groom each other simultaneously.

Allomanipulate: One animal rubs, pats at, or fondles the fur, orifices, or extremities of another (not including genitalia).

Social locomotor: Involves travel while in contact with another.

Buddywalk: Involves travel while in contact with another.

Carry/cling: One animal transports or is transported by another.

Ventral carry/cling: While standing or moving quadrupedally, the focal animal transports another which is hanging onto its ventrum (carry). The walk is quadrupedal or tripedal (if the focal animal is using one of its arms to support the passenger). The focal animal is transported in the manner described above (cling).

Dorsal or lateral c/c: While standing or moving quadrupedally, the focal animal transports another on its back, side, neck, shoulders, or head (carry) or is transported by another in this manner (cling).

Extended arm carry: An animal carries another (usually an infant) in the palm of the hand and walks either tripedally (carrying the infant football style) or quadrupedally (carrying arm is inverted and weight is on the backside of the hand/wrist).

Leg drag: An animal holds onto anothersÕ ankle and is pulled along in the direction in which the latter animal is traveling.

General social contact

Active maintenance of contact: Consists of a group of actions which establish, regulate, or maintain contact with another.

Withdraw: One animal moves from within to beyond contact distance of another.

Approach: One animal moves from beyond contact distance to within contact distance of another.

Maintain: Preserve social distance with a withdrawing animal.

Follow: One animal maintains proximity (1-3 BL) with another and simultaneously parallels its route of travel. Delay of follow is minimal.

Restrain: One animal physically prevents another from moving out of contact distance.

Fetch/retrieve: One animal approaches and makes contact (grasp, pull, push ) with a withdrawing animal or one who is beyond social distance (4 m), which results in that individual returning to an original location or group.

Herd: An individual guides the movement of an individual or troop by a series of approaches and withdrawals.

Greet: Involves a group of actions which occur when individuals are seeing each other for the first time or are entering into the contact distance of one another. These actions are typically brief (momentary to 5 sec).

Muzzle-muzzle: One animal places its face within 15cm of anotherÕs muzzle.

Kiss: One animal places its lips against the head or face of another.

Touch: One animal reaches with any limb and makes contact with another or any part of the body except the genital region. The contact is momentary (1-2 sec).

Embrace: One animal wraps and/or legs around the body of another. Duration is short (<= 10 sec).

Grasp: One animal momentarily seizes another with the hand(s).

Offer food: An animal holds food in the hand and then extends that hand towards another.

Inactive social contact: Individuals are inactive, are within social proximity (0-4 m) of one another, and have the option to withdraw form social proximity.

Huddle: Tow or more individuals are inactive with torsos in direct contact, lateral or ventral. Arms may be wrapped around one another.

Rest in contact: Individuals are inactive with some part of the body (exclusive of the position described in the huddle) in contact ie., back to back, toes touching, arms intertwined.

Rest proximate: Individuals are inactive, not in contact, but within arms length of one another.

Rest distal: Individuals are inactive, not in contact, greater than arms length away but within 4 m of one another.

Submissive/avoidance

Turn away: An animal moves its body so that it is oriented away from another, but does not travel.

Avoid: An animal moves out of the path of an approaching animal or takes a less direct route around that animal.

Hide: An animal removes itself from the view of another. This may occur following an aggressive attack or threat.

Crouch/crawl: This behavior can take two forms: 1) An animal bends all four limbs, presses its ventrum to the ground, and may try to travel while in this position: or 2) the animal may crouch while in one of the sitting positions by lowering the head, hunching the shoulders, and often covering the head with an arm.

Present: May take two forms. One form is similar to a sexual present, but is much briefer. It may be accompanied by a series of brief glances directed towards the presentee. An animal may also Òoffer-upÓ or present an arm to the presentee. (specify act)

Run away: An animal moves rapidly (with a running gait) away from another.

Supplant

Supplant position: An animal approaches another which then moves away. The former assumes the position of the latter.

Supplant take object: An animal takes an object from another or picks up one which was dropped as the former approached.

Threat: Posture, facial expression, or movement, usually accompanied by a vocalization, which results in keeping rivals at a distance, obtaining desired objects or space, and controlling anotherÕs behavior without undue expenditure of energy or risk of injury (McFarland, 1982, slightly modified).

Threat: May appear to be undirected and for our purposes, does not involve movement towards another.

Stare: An animal looks towards and fixates on another for an extended time. The brow is furrowed and the face is tense.

Tight lipped face: An animalÕs lips are compressed tightly so that the upper and lower lips are somewhat protruded.

Rigid quadrupredal stance: An animal assumes a quadrupedal stance, with the legs widely spaced and placed behind the torso. The arms are rigid with elbows rotated outwards, and the weight of the upper body on the knuckles.

Rigid quadrupedal walk: From the rigid quadrupedal stand, an animal moves forwards with short stiff steps. The walking speed may be faster than normal, creating a trot like gait. This is undirected.

Object slap: An animal slaps ground, rock, wall, tree, door, etc., with the palm or back of the hand. This usually results in a loud sound.

Head divert: One animal turns its head away from another in an exaggerated manner and glances repeatedly back at them.

Yawn: The mouth opens widely, head tips back, lips are pulled back so that the teeth are exposed. Looks like exaggerated form of a yawn.

Chest beat: An animal repetitively strikes the chest or belly area with outstretched or cupped hands. The animal is usually bipedal; either walking, running, standing, or standing and rapidly swaying. An animal may also strike his/her chest once with a cupped hand. This can occur in any posture. The chest beat, like all agonistic behavior, may include a vocal component such as a roar or pant hoots. Note: chest beating can be observed in a number of contexts: i.e., lone and social play, reproductive, and agonistic.

Ground slap: An animal thumps the ground with one or both hands. The strike may be with open hands, back of hands, or side of closed fists.

Directed chest beat: An animal chest beats while oriented towards another.

Directed object slap: An animal strikes at an object with an open hand while oriented towards another.

Open mouth threat: An animal looks at another and lunges forward with a tense, open-mouthed expression. The lips are raised and pulled back so that the canines are exposed; muscles in the forehead are taut.

Threat display: A series of threats, postures, facial expressions, or movements, that are accompanied by a roar, bar, or rumble vocalization. Many of the threat displays include a rapid advance directed towards specific individuals.

Bluff charge: An animal runs quadrupedally on the diagonal past another but does not make contact. The bluff charge usually in a slide, and may be accompanied by an object flail, drag, or throw.

Rush charge: An animal runs quadrupedally towards, but stops just short of another.

Object grab: One animal grasps or snatches an object (food, browse, or otherwise) from another.

Attack: Includes hostile acts involving active pursuit or physical contact between two individuals.

Hit: While rapidly charging towards another (bipedally or quadrupedally), one animal reaches out and strikes the other with an open hand or fist.

Hit with object: An animal uses an object to strike out and makes contact with another. This behavior occurs at the end of a charge.

Hit/slap: An animal strikes another with its hand(s), but there is not charge component to this behavior.

Push: Animal uses arms or legs to forcefully move another away.

Pull: An animal grasps another and forcefully moves them closer.

Chase: An animal runs in pursuit of another which is rapidly withdrawing.

Bite: An animal closes its mouth on the extremities or body of another. Damage may or may not occur.