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Species: Hopping Mouse (Notomys alexis)
Use: General Activity
Authors: Meredith Stanley, Department of Zoology, Monash University
Methods: NA
Publications/Presentations: Meredith Stanley, 1970. An ethogram of the Hopping Mouse, Notomys alexi. Z.f.Tierpsychol. Bd. 29, Heft 3.Behavior of solitary animals
Quadrupedal walk: A slow pace of four steps to the stride. Each limb is moved asynchronously; the extension of one limb is followed by extension of the contralateral one. The hind-feet touch the ground beyond the footprints of the fore feet. The tail is held horizontally above the substrate.
Quadrupedal run: With diagonal limb co-ordination
Quadrupedal hop: A medium speed pace with two or three steps to the stride, and in which the hind limbs move in synchrony. The fore-limbs alternate with the hind in striking the substrate, but they may not be entirely in synchrony; one may strike the substrate earlier than the other, and behind it. At no time does the animal lose contact with the ground, so the distance of each stride is no greater than the extended body length of the individual. The tail is held horizontally off the ground, and seems to have no function in this type of locomotion.
Quadrupedal ricochet: A fast pace with two steps to the stride. Differs from the much slower quadrupedal hop in that the fore-limbs are moved in synchrony, and there is a period during which all four limbs are off the substrate. This follows a powerful kick-off with the hind limbs. The hind-limbs are gathered under the body, and the fore-limbs are stretched out ready for landing. The fore-limbs contact the ground together, and the hind-limbs follow, landing ahead of the fore-limbs, which move caudal as the hind-limbs touch down. The fore-limbs are tucked under the chin as the extension of the hind-limbs propels the animalÕs next leap. The tail acts as a rudder and counterweight.
Bipedal walk: The animal stands upright. The hind-limbs move alternatively in short steps. The tail is either propped against the substrate so that it acts as the third leg of an effective tripod, or it is held off the substrate to function as a counterweight. The direction of movement may be forward or sideways, or even backward for short distances.
Bipedal hop: The animal stands upright. It moves forward with short jumps, with the hind-limbs in synchrony. The tail is used as a prop or a counterweight.
Bipedal ricochet: This has been described in detail by Marlow (1969). This gait is similar to the fast straightaway bipedal locomotion in Dipodomys merriami, which has been described in detail by Bartholomew and Caswell (1951).
Climbing: Notomys alexis can climb through tussocks of grass, fallen branches and heaps of sticks. They run along slender branches, and leap from branch to branch. The tail is used for balance. It is not prehensile, but it may be flexed at any point, and curved to distribute its weight most appropriately. It may be thrown forward over or under the animal to check forward momentum when the animal lands after leaping. It may be used tripod fashion if an attempt is made to reach a branch above the animalÕs head. The fore-limbs are able to pull the body to a higher branch. They can also transport the animal monkey-bar fashion across the wire-netting roves of cages. While climbing vertical or even inwardly sloping wire-netting, the limb movements are similar to those in quadrupedal walking and running.
Crouch: Occurs when the animal is quiescent.
Bipedal-rounded: Occurs when the animal is resting, nibbling food, chinning, licking its paws, etc.
One-paw-up: The animal stands with one fore-limb raised. This posture appears to be indicative of alert, investigatory or indecisive attitudes, since it is usually followed by activity.
Elongate: A quadrupedal posture which is associated with investigatory behavior, including social contacts.
Investigatory uprights: Three bipedal postures which are associated with investigatory behavior.
Care of the body surface: Licking with the tongue, nibbling with the incisors, combing with the paws, scratching with the toes and shaking are the means of cleaning the body surface. There are eight discrete grooming movements.
(a) The fore-paws are held beneath the mouth, and are licked
(b) The head is lowered slightly, and the nose is brushed vigorously with the fore-paws. Then the head is lowered further, and the arms are swept in synchrony over the head and ears
(c) The head is thrust forward so that the throat is horizontal. The fore-paws are swept over the fur around the glands in this area
(d) The head and fore-limbs are twisted to one side so that the flank can be licked and combed. If the head is twisted further the shoulder and side can be reached. Either side may be cleaned first.
(e) The head is tucked under the body and the ventrum is licked and combed.
(f) The base of the tail is picked up in the paws and as it is licked from base to tip it is swept to the side. After the tuft has been licked, the tail is dropped from the paws.
(g) The head is tilted to one side and the hind-foot on that side is lifted and thrust forward. It is held in the hands while being licked and nibbled. Particular care is given to the toes. Either foot may be cleaned first.
(h) The ear region is scratched with the toes of one of the hind-feet.
Stretching and yawning: Occur most frequently during arousal.
Feeding and drinking: Foraging for seed is part of the daily routine for this species. Seeds are picked up in the mouth but they are usually held in the paws while nibbled. Some seeds (e.g. millet) are shelled. Blades of grass are grasped in the paws, pulled towards the mouth, and a piece about three centimeters long is bitten off. This is presented end-on to the mouth. The paws continue to feed the grass into the mouth until almost all has been chewed. Pieces of apple, etc., are steadied with the paws and nibbled.
Water is lapped up with slow movements of the tongue. However, if some succulent food is available, water will be taken readily by some individuals, but not by others.
Defecation and micturation: Defecation is not associated with any special behavior. It occurs approximately once per half-hour. The rate of defecation may rise as much as tenfold during arousal and if the animal is handled or placed in strange surrounds.
Notomys alexis micturates from a crouch posture with the tibias almost horizontal, the tail raised and the ventrum close to the substrate.
Construction and maintenance of burrows:
Digging: The fore-paws are moved alternatively, with an extremely rapid scraping action. This builds a pile of material beneath the animal or just behind it.
Kick-back: Once a pile of material is established, the hind-limbs move together, thrusting the spoil out behind the animal. During the kick-back, the body is braced by the fore-limbs.
Packing: The walls, roof and floor of the tunnels, shafts and chambers are patted and packed down with the fore-paws. The packing movements are extremely rapid. The paws may be moved in synchrony or alternatively.
Turn-and-push: The nose and forehead are used as a shovel to lift and push substrate along the tunnel, and to pack it firmly against the walls and roof.
Construction of nests above ground: Finlayson (1940) reported that Notomys are very seldom seen in the daytime, except momentarily when one may be dislodged from a surface nest. Surface nests are also constructed by captive animals, even when burrows are available.
Sleeping postures:
(a) Most often animals lie on their sides with the head thrust forward and the upper hind limb extended.
(b) Alternatively, the animals lie on their backs with the head forward and the limbs tucked up close to the belly, or rigidly extended.
(c) The animals crouch on all-fours with the head tucked under the belly so that it supports some of the animalÕs weight. This position is usually adopted during hot weather, but occurs in cooler weather also.
Chinning: Small objects such as sticks, roots and blades of grass are held close to the mouth. The head is then thrust forward so that the throat region is rubbed across the object. The object is either dropped or sniffed and chinned again.
Drag-marking: The perineal region is lowered and touched upon the substrate. This action resembles micturation except that no elimination of urine occurs.
Arousal and routine inspection: Awakening is indicated by the opening of the eyes. Investigatory upright postures are adopted and the air is sniffed. The animal stretches and may yawn at the same time. Frequently a long and thorough grooming session follows stretching, but the animal may walk immediately to the burrow entrance. At the entrance the animal stops and tests the air. The ears are pricked and turned from one direction to another. The animal then emerges from the burrow, and moves around the cage. There are frequent pauses to test the air. A few seeds may be nibbled, but the surrounds are investigated before a long feeding session begins.
The movements of an animal investigating its familiar home-cage during arousal are distinct from those of an animal investigating unfamiliar surrounds. The former may be referred as routine inspection, as distinct from exploration.
Exploration: Exploration was observed by transferring an animal in its familiar nestbox to a new cage. Most individuals were reluctant to leave the familiar box. They paused and tested the air before venturing out. They seldom moved far before returning to the box. Eisenberg (1963) observed similar behavior in heteromyid rodents and suggested that this procedure enables the animals to retain their orientation to the one familiar area in the new environment. During the first short bursts of activity, the ears are laid back and the eyelids retract a little. Micturation and defecation are frequent. The new surroundings are marked with urine and probably with secretions from glands in the perineal region. Suitable objects are chinned. Objects are sniffed from a distance and approached slowly. They are touched with the nose and fore-paws. It seems that touch plays a fairly important role in the examination and possibly recognition of objects.
Social BehaviorVisual communication: The importance of vision is implied by the rapid increase in play which occurs within two days of the opening of the eyes. The suddenness of this increase militates against the idea that it is mainly due to the improvement of motor activities, although this undoubtedly plays a significant role.
Visual perception of young (even those from another litter) elicits attempts to retrieve, and other maternal responses in females with young. These responses occur even if the young are silent and enclosed in a transparent container, which prevents odors from the young reaching the parent.
Auditory communication: Non-vocal sounds produced by an animalÕs activities, together with vocal and non-vocal signal, are associated with the behavior of this species.
Activity sounds: These are sounds produced incidentally during activities such as locomotion, burrowing, biting and chewing and so on. They do not exist primarily as a means of communication, but they probably provide other animals with information about what is going on. Foe example, the sounds made by the approach of an animal which is out of sight will elicit submissive postures or flight in a non-aggressive listener.
Non-vocal signals: Sounds which can be included in this category are sucking noises and clicks made by neonates. Their communicatory significance is not known. Mechanically produced signals such as drumming, tooth-grinding and tooth-chattering, which occur in the heteromyid rodents (Eisenberg 1963) and many other rodents, have not been detected.
Vocal signals: Four types of audible sounds have been recognized. The four sounds may be referred to as piping, squeaking, grating and twittering.
Piping is emitted only by neonates. Squeaking is emitted by adult and juvenile animals which are injured, confined in very small boxes, or held firmly in the hand.
Squeaking also occurs in young animals which have lost contact with their siblings or parents, and in young animals which are disturbed in the nest by movements of the parents or nest mates. The quality of squeaks varies with age. Squeaks are accompanied by ultrasonic sounds with frequencies greater than 20 Hz.
Grating is emitted by neonates and may accompany the squeaks of older pups.
Twittering is a series of high-pitched syllables of approximately 0.01 sec. Duration, and uttered at a rate of approximately 14/sec. Ultrasonic sound accompanies twittering. It only occurs during chasing and appears to be produced only by male animals.
Olfactory communication: Olfactory examination of the glandular areas in other individuals is very frequent and areas where drag-marking and chinning have occurred are investigated. Auditory and visual perception of the approach of another animal elicits testing of the air, and the nose is pointed in the direction of the other animal.
Naso-nasal: The noses of both participants touch each other briefly. Naso-nasal contacts generally precede other contacts.
Naso-gular: The investigation of glands in the gular region may or may not be mutual. If mutual, the two animals face each other and turn their heads to one side, so that noses are positioned close to the glands. When the investigation is not mutual, the investigating animal usually crouches in front of an upright animal and can reach the gland by pointing the head upwards. Alternatively the investigator may approach from the side, place its fore-paws on the other animalÕs head and turn it to one side so the throat is exposed. Naso-gular contacts usually follow a naso-nasal contact.
Naso-perineal: This likewise may or may not be mutual. When both animals are attempting naso-perineal contact, they may circle each other.
Naso-caudal: The investigating animal approaches its subjects from behind. It sniffs at the tip of the tail, then picks the tail up with the fore-paws and examines it. Should the subject hold its tail upright, the investigator may grasp it near the base and pull it down. Naso-caudal contacts have only been observed between males.
Naso-cervical: The investigator approaches from the side and sniffs the base of the ears and the nape of its subject.
Amicable behavior
The term amicable is used here to describe social behavior which lacks agonistic elements.
Social grooming: Nibbling and combing of the fur of another animal occurs frequently. All parts of the body may be groomed by an associate, but most attention is given to the rump, nape and ears. Social grooming is cooperative to the extent that the subject appears to relax and may be rolled over or pushed into place by the groomer.
Huddling: Animals which are bonded to each other huddle together during feeding and resting.
Walking-over: One animal will walk or leap over another when in a burrow and above ground.
Crawling-under: One animal pushes its way under the belly of another, usually from one side. This is a common component of burrow behavior and play, but is not often seen in social activities above ground.
Nudging: One animal nudges anotherÕs sides with its nose or head. This may occur during huddling.
Communal nesting and sleeping: Regardless of age, reproductive state and age, animals which are caged together attempt to share a nest-box and sleep together, even if space in the box is limited, and other nest-boxes are available. Communal nesting has been observed over an ambient temperature range of 1¼ C to 37¼ C.
Agonistic BehaviorStalking: A furtive slow quadupedal approach towards another animal, made by the aggressor. During stalking, the eyes are open and the ears pricked forward. The neck is stretched out, and the fur on the nape may be raised.
Rushing: The aggressor runs up to its opponent and attempts to bite and scratch it. During the approach the head is thrust forward, the ears are pricked, and the fur on the nape may be raised.
Attack leap: The aggressor leaps into the air and attempts to come down on top of the opponent.
Escape leap: The opponent may avoid an attack leap by leaping out of the aggressorÕs way. Escape leaps are often directed over the aggressor, who must then turn round before resuming the attack.
Chase and Flight: An opponent fleeing from the approach of an aggressor may be pursued. Bipedal and quadrupedal ricocheting occur. If the chase is very close, the opponent may be bitten on the rump and tail. If the pursued animal is able to move out of sight of the aggressor, chasing will stop until the opponent is sighted again. Alternatively, chasing may be terminated by the aggressor. Should this happen, the opponent will leap out of sight (if possible) and stop. In dim light, motionless opponents are frequently overlooked, but movements attract attention and stimulate attack and chasing.
Aggressive mounting: An aggressor may chase its opponent until close enough to rear and grip its flanks with the fore-limbs. If the opponent continues to move, the attacker may retain its grip on its opponent while following by walking on its hind legs. The rump of the opponent can be bitten from this position. Small bites on the rump are the most common wounds observed.
Sparring: Should aggressor and opponent meet face-to-face, the aggressor may rear and strike the opponent with its for-limbs. In defense the opponent may also rear and ward off the attack with its for-limbs. The fore-limbs may become locked. Sparring is of approximately one to three seconds duration, and the movements are extremely rapid.
Locking fight: If an aggressor catches an opponent, the two animals may roll over with their ventral surfaces pressed close together. They attempt to scratch and bite each other. Locking fights are of very short duration.
Sexual BehaviorFollowing: As in chasing, one animal pursues the other. In following, the movements of both male and female are slow. The male may close on the female from behind and attempt to mount.
Riding: This occurs if a male manages to grip the femaleÕs flanks while she continues to move forward. The male moved behind her at a bipedal walk or hop.
Patting: Prior to mounting, the male may pat on the rump of the female, with his fore-paws. The male may also groom the rump of the female at the same time.
Mounting: The male rears behind the female and grips her flanks with his fore-limbs. His nose may be thrust into the fur on the femaleÕs nape.
Lordosis: A mounted male cannot achieve intromission unless the female raises her hind quarters and tail. Often the female adopts this posture in front of the male before the male has mounted. This suggests that pressure of a maleÕs fore-limbs on the femaleÕs flanks is not always needed to induce lordosis, as it appears to be in Rattus (Bartnett 1963).
Copulation: Comprised of intromission, thrust and ejaculation.
Parental behaviorPreparturient behavior: Nesting activity in pairs of animals prior to the birth of young may be either low, in which case both animals sleep on a cushion of grass, or high, in which case an elaborate spherical nest is built and cared for each night.
Parturition: The time of parturition was known in five instances. These five litters were born during the day. In three instances parturition occurred between 1500 and 1900 hours.
Nursing posture: Males and females crouch over the young. Females allow the young to suckle in this posture. The nursing posture differs from a normal crouch in that the hind-limbs are a little further back, and the back is arched, so little is any of the parentÕs weight falls on the young. Males and females with new-born young may lapse into a normal crouch, so crushing the young, which respond by piping or squeaking, and wriggling. This apparently stimulates the parent to arch its back and readopt the nursing posture.
Pulling-under: The parent reaches towards and grasps the young with the fore-paws and pulls it under the belly so that nursing can begin. Neonates are rolled onto their backs during this movement.
Pushing: The young are pushed away from the parent by means of the fore-paws.
Grooming: Neonates are held in the fore-paws, lifted to the mouth and are licked and nibbled particularly around the nose and mouth. They are also held on the ground and are rolled over while being licked or nibbled. From this position the perineal region can be reached and is given most attention. Grooming the older offspring resembles social grooming between adults, except that the young roll onto their backs and the parents groom the ventral surface as well as other parts of the body.
Retrieving: If young stray from the nest the parents follow and retrieve them. This varies according to the size of the pups. Neonates are grasped at the nape. Lifted off the ground and carried back in the parentÕs mouth. The retriever walks or hops bipedally. When the young can no longer be lifted they are grasped between the parentÕs fore-limbs and dragged back/ The retriever moves back with a shuffling gait.
Defense of the young: The litters of seven females were disturbed daily so that the young could be weighed etc. Normally these females stood over their young and had to be pushed away before the young could be reached. Only once did a female attack in defense of the litter. The female leapt at the experimenterÕs hand, bit it, then leapt back into the nest. Males likewise rarely attack in defense of the nest or young.
Patterns of Parental Behavior: The motor patterns which comprise nursing, grooming, pulling-under, patting, pushing and retrieving are very similar to the motor components of communal sleeping, social grooming, feeding and manipulation of nest-materials. The motor patterns also occur in play. Then during parenthood they are re-elicited by age dependent stimuli from the young. As the young grow, the nature of the stimuli received from them changes and the parental responses change accordingly or cease altogether.
The mother-offspring bond: Four litters were left with their mothers for at least 12 weeks. In each case the mother-offspring bond was not noticeably weakened. In each cage a choice of nest boxes was available, but the young remained with the mothers in the box in which they were reared. In one case a second liter was born when the first litter was 32 days old. The mother-offspring bond was not affected by the existence of the second litter.
Behavior in conflict situationsIntention movements: If N.alexis vacillate between advance and inaction they adopt the one-paw-up posture. This is probably the first movement in the sequence of movements which comprise quadrupedal walking. This posture probably signifies the intention to move.
Ambivalent behavior and alternation: During aggression and play an animal may execute a series of vertical leaps (ambivalence), or a series of leaps in which forward and backward leaps alternate (alternation). This is done in front of another animal. The leaps appear to be modifications of the attack-leap towards and animal, and the escape-leap away from an animal. Ambivalent vertical leaping appears to occur when the motivations and movements associated with attack-leaping and escape-leaping occur simultaneously. Movement towards the other animal in counteracted by movement away from that animal.
Redirected attack: In agonistic encounters the aggressor and less frequently the opponent may bite and scratch pieces of bark, sticks or stones instead of other animals.
Displacement activity: When behavior patterns such as grooming, seed-nibbling and burrowing appear to occur out of context, they are described as displacement activities. Displacement activities frequently occur during courtship, aggression and exploration. They also occur when animals are confronted with unusual stimuli, or stimuli at unusually high intensities, which are not sufficiently unusual to elicit prolonged startle responses or flight.
Social Organization(a) Encounters between strangers which have been kept in isolation for several days and then put together in a cage which is unfamiliar to both, are characterized by the occurrence of a brief initial period of aggression followed by contact-promoting behavior and formation of permanent bonds. These bonds even form in the absence of sexual stimuli associated with oestrus.
(b) Behavior patterns such as mounting, social grooming, huddling, nudging and walking-over occur frequently during routine behavior. Possibly these behavior patterns strengthen bonds between group members by providing stimuli similar to those associated with sexual and parent-young interactions.
(c) There is synchronization of some activities and division of labor which result in a group co-operation (no intention or consciousness implied).
(d) Group members nest together and frequently feed side by side.
(e) Behavior patterns which promote individual recognition occur very frequently. As group members move about during routine activities they pause to sniff noses and to carry out other investigatory contacts.
(f) Conspecifics which are not members of a group are attacked by members of an established group. These attacks are usually very savage and the foreign animals may be fatally wounded. If group members are removed for a few minutes and handled so that they carry strange scents, they may be attacked when returned to the group. Usually they are recognized before they are wounded and are then accepted into the group.
(g) Group members are tolerant of neonates and juveniles. Some members of the group participate in rearing the young. Older siblings and other adults crouch over young and may groom them. Older siblings will retrieve young. Females with young suckle each othersÕ young.
(h) In captivity the young, which mature within a group, remain members of the group and there is no evidence that the older group members attempt to reject subadults, or that the sunadults attempt to break away from the group. The situation may be different among free-living population.
(i) The maximum density, above which phenomena such as excessive aggression, neglection and destruction of young, failure of the female oestrus cycle and hypertrophy of the adrenals occur, is not known but it is probably high.