Mother-young Contact Research Articles

Diurnal cycle of mother-young contact in Norway rats

Mother rats maintained on a LD 12:12 photoperiod (lights on 0800 hrs) had longer contact bouts with their offspring during the day than during the night and maternal brain temperature peaked during the night. When the daily temperature cycle was suppressed by removal of adrenal and ovarian hormones, the daily maternal contact cycle was also suppressed. These data are consistent with a thermal model for the limitation of mother-young contact bout duration.

Energetic limits on reproduction: Interaction of thermal and dietary factors

The time that food-restricted Norway rat dams spent in contact with their offspring was elevated only during that portion of the day in which their body temperatures were depressed. These data support a thermal model for the limitation of mother-young contact. The depression in maternal body temperature appeared to be due to a direct limitation on available fuel, rather than being mediated by a depression in circulating hormone levels.

Determinants of mother-young contact in Norway rats

Rat dams choose to care for their pups in a relatively warm area, apparently because they have an elevated thermal set point for the regulation of their body temperature. Since the duration of their contact bouts with their pups is limited by an acute hyperthermia that they experience while on the pups, their choice limits the time that they can spend with their pups. When dams could choose the temperature at which they cared for their young they spent only about half the time in contact with their offspring as did dams caring for their pups at the ambient temperature of the laboratory. We conclude that rat dams do not attempt to maximize the duration of their contact bouts with their offspring. Dams also do not attempt to minimize the amount of time that they spend away from their offspring. The duration of the intervals between contact bouts was influenced by the ability of the dams to dissipiate the heat gained during the contact bout with the pups. Again, dams did not seek out a cool area in which to spend their interbout intervals, preferring to remain in relatively warm areas. Their thermal preference facilitated the retention of their body heat and prolongation of the interbout intervals. Dams may return to the nest periodically for brief bouts during which the state of the pups is monitored. Pups were found to play both passive and active roles in modulating the overall pattern of maternal contact, for dams maintained contact with pups if the pups were cool, but failure to attach to the nipples soon after contact was established frequently led to rapid bout termination, particularly with warm pups. Contact is maintained if the pups are cool or if they attach to the nipples. Finally, it was found that pups could actively curtail interbout intervals by emitting ultrasonic vocalizations.

Contact-promoting behavior, social development, and relationship with parents in sibling juvenile degus (Octodon degus).

This study describes infant socialization in captive parent-young units of the caviomorph rodent Octodon degus. Types of parent-young contact (huddling or squatting) and social interaction (body nosing and accompanying behaviors) are described and their ontogenetic trends examined between postnatal Days 1 and 46. Fathers spent less time than mothers in contact with the young. Mother-young contact decreased postnatally, whereas the amounts of mother-young and father-young social interaction, measured in terms of body-nosing exchanges, showed a continuous increase postnatally; sibling interactions also showed a continuous increase. Father-young interactions tended to be dominated by the father. Young reared with the father cohabiting huddled less with their mother, and engaged in less body-nosing, than young reared in the father's absence. Observations suggested that paternal control of the young may curb juvenile interactions. Young observed without their parents in an unfamiliar enclosure did not groom or "play" as in their home cage with parents present, but engaged in relatively more vocalizing, neck-nosing and forepaw-clasping.

Prolactin-steroid influences on the thermal basis for mother-young contact in Norway rats.

Norway rat dams have a chronic elevation in core temperature throughout the first 2 wk postpartum, a situation that makes them vulnerable to a further, acute rise in body temperature during contact with their young. Prolactin appears to contribute to the chronic elevation of maternal temperature, probably by stimulating the secretion of progesterone, which then elevates the maternal thermal set point.

Relocation of the site of mother–young contact: Maternal transport behavior in Norway rats.

Relocation of the site of mother–young contact: Maternal transport behavior in Norway rats.

Olfactory mediation of mother–young contact in Long-Evans rats.

Twenty-one-day-old Long-Evans rat pups, unlike 16-day-old pups of the Wistar strain, (a) find the odors emitted by adult virgin females of their strain attractive, (b) find the odor of the anal excreta of adult virgin females of their strain attractive, (c) find the anal excreta of virgin female rats as attractive as those of lactating rats of their strain, and (d) are less attracted by the odor of the anal excreta of a lactating rat than by the odor of the lactating rat itself. The results indicate that descriptions in the literature of olfactory communication between Wi star rat dams and their young cannot be generalized to rats of other strains or ages.

Thermal control of mother-young contact in rats

The factors involved in the control of nest bout duration by mother rats were analyzed. Disruption of prolactin or adrenocortical secretions halted the normal progressive decline in daily nesting time, but the behavioral effects of hormone disruption were not mediated by a suppression of milk delivery. Rather, these hormones stimulate a chronic elevation in the body temperature of mother rats which makes mothers vulnerable to the acute thermal consequences of huddling with their litter. The temperature of a mother rat rises further after her ability to dissipate heat decreases when she comes in contact with her young, a rise that eventually limits the duration of nest bouts. Decreasing the efficiency of heat dissipation during nest bouts by elevating room temperature, pup temperature, or by removing the tail (a major pathway for heat dissipation) decreased nest bout duration. Increasing the rate of maternal heat loss by decreasing room temperature, pup temperature, or by partially removing the insulating fur of dams increased nest bout duration. We conclude that nest bouts are normally limited by a rise in maternal temperature, and that the rate of temperature rise determines the duration of each bout.

Field and Laboratory Studies of the Vocalizations of Talapoin Monkeys (Miopithecus Talapoin)

AbstractThe vocal repertoire of talapoin monkeys consists of eleven basic vocal types within which 31 different sounds are described, including all intermediates, "lip-smacking" and branch noises (linked with cohesion calls). Calls are of short duration (1/20s to a few seconds). Some of them have a daily rhythm of emission. Their intensity is variable, the call range varying accordingly from a few to several (more) hundred meters. Talapoin calls are composed either of low-pitched structures, of high-pitched ones, or an association of the two. Seven calls, of the eleven basic types possess low-pitched components (pitch = 0.5 to 1KHz) giving them a common quality, constituting what may be called the "talapoin voice". Two graded systems have been described. One, the most graded, is composed of the aggression-flight vocal types; the second is linked with group cohesion. The important level of gradation within the vocal repertoire of this forest species contradicts the classical concepts which ascribe a "discret" repertoire to monkeys living in a closed milieu. The gradation of the vocal system of a species may be related more to an abundance of social contacts than to the structure of the milieu (multimodality of signals exchanged over short distances). During ontogeny, the vocal repertoire changes in both type and frequency of use. The structural modifications are either continuous, with the growth of individuals, or discontinuous with the sexual maturity of males. Under conditions of average excitation, differential call distribution and their relative frequency according to different individual classes lead us to generalize that the vocal behaviour of a particular class in a group (age, sex and social status) always differ qualitatively and quantitatively from that of other classes. Under conditions of high excitation, differential call distribution and their relative frequency according to different individual classes, lead us to generalize that any individual can give any call type when submitted to adequate stimulation. This difference between the real potentiality of a given individual and actual use in the wild is essentially related to the change of stimulating context as the monkeys grows older. In order to vocalize, the talapoin must receive stimulation which increases its excitation level and directs its response. Furthermore the excitation level does not directly determine a particular vocal type. The vocal response varies according to the situation and is adapted to the stimulus context. We distinguish between stimuli which propagate calls within a social group from those initiating calls. The former are essentially calls of congeners, the latter are more often visual, visual auditory, auditory then tactile. The majority of talapoin calls control the spatial distribution of the troop members in relation to external events (cohesion calls system, aggression-flight calls, mother-young contact calls). Choruses however have a more complex social role which is not completely understood. With a maximal energy concentrated arotmd 0.9KHz, the "lost" calls of young seem to be adapted to penetrate the forest milieu. The presence in certain calls of high-pitched components appears to be linked principally to the rise of the excitation level of the vocalizers. With eleven vocal types, the talapoin has a repertoire comparable to that of other monkeys. It is sympatric with Cercopithecus nictitans, C. cephus, C. pogonias and C. neglectus with which it shares a number of functional categories of calls, features probably imposed by forest conditions (poor visibility, winged predators, ...) examples are the cohesion system, dispersion calls, aggressive alarm to birds). Conversely, the physical structure of calls of genus Miopithecus and Cercopithecus have little in common. The frequent choruses in talapoin seem to be related to a more complex social life than that of the Cercopithecines. The talapoin is differentiated strongly from the sympatric species in the absence of loud calls, the specific characters of call structures and their more graded nature. A similar degree of differentiation is found in the morphological, physiological and eco-ethological traits characterizing the talapoin (GAUTIER-HION, 1970, 1971 a, b). Although some talapoin calls are higher-pitched than those of macaques, there are affinities between the vocalizations of talapoin and macaques : both have graded call systems arising in aggression-flight behaviour and there are similarities in calls with tonal structure: types 2 of talapoin; clear calls of M. mulatta (ROWELL & HINDE, 1962); "coos" and "high-pitched musical notes" of M. nemestrina (GRIMM, (1967); "coos" of M. speriosa (BERTRAND, 1969); "coo sounds" of M. fuscata (GREEN, in press). Finally, there is a close structural resemblance between the "lost" calls of infants talapoin and rhesus.

Maturation of tempeature homeostasis in the rat.

Maturation of tempeature homeostasis in the rat.