Interactions between infant growth and survival: Evidence for selection on age-specific body weight in captive common marmosets (Callithrix jacchus)

The objective of this study is to investigate factors influencing infant survival in captive common marmosets. We investigated the influence of age-specific weight, litter size, caging, and the presence of helpers on survival to 6 months of age in 189 Callithrix jacchus infants. Infant survival was analyzed using Cox Proportional Hazards regression, and fitness functions were plotted to explore the relationship between survival and growth. Results indicate that weights at birth and 120 days significantly affect future survival probability. Litter size significantly influences survival prior to 60 days of age with larger litters having poorer survival. Males and females did not have significantly different survival and the presence of helpers in the group did not influence survival probability. Patterns of survival with respect to age-specific weights suggest stabilizing selection on birth weight and directional selection on weight at 120 days of age. Am. J. Primatol. 42:269–280, 1997. © 1997 Wiley-Liss, Inc.     

Costs of Caregiving: Weight Loss in Captive Adult Male Cotton-Top Tamarins (Saguinus oedipus) Following the Birth of Infants

We examined changes in weight for 10 captive adult male cotton-top tamarins (Saguinus oedipus) from before the birth of infants through the first 16 weeks of infant life. Compared to before birth, males weighed significantly less in Weeks 1–4, 5–8, and 9–12 following the birth. Weights in Weeks 13–16 did not differ significantly from prebirth weights. Maximum weight loss for individual males ranged from 1.3 to 10.8% of prebirth body weight. Males in groups with fewer helpers lost significantly more weight than ones in groups with more helpers. For the 3 males that had no helper other than their mates, weight loss was particularly striking, ranging from 10.0 to 10.8% of their prebirth body weight. These results suggest that caring for infants is energetically costly, and that in this cooperatively breeding species, the presence of more individuals to share the burden of infant carrying reduces the cost to individual caregivers.     

Birth Timing and Behavioral Responsiveness Predict Individual Differences in the Mother–Infant Relationship and Infant Behavior During Weaning and Maternal Breeding

There is a great deal of variability in mother–infant interactions and infant behavior across the first year of life in rhesus monkeys. The current article has two specific aims: (1) to determine if birth timing predicts variability in the mother–infant relationship and infant behavior during weaning and maternal breeding, and (2) to identify predictors of infant behavior during a period of acute challenge, maternal breeding. Forty‐one mother–infant pairs were observed during weaning when infants were 4.5 months old, and 33 were followed through maternal breeding. Subjective ratings of 16 adjectives reflecting qualities of maternal attitude, mother–infant interactions, and infant attitude were factor analyzed to construct factors relating to the mother–infant relationship (Relaxed and Aggressive) and infant behavior (Positive Engagement and Distress). During weaning, late born infants were more Positively Engaged than peak born infants (ANOVA, P < 0.05); however, birth timing did not affect the mother–infant relationship factors Relaxed and Aggressive or the infant attitude factor Distress. During maternal breeding, early born infants had less Relaxed relationships with their mothers than peak or late born infants, higher Positive Engagement scores than peak or late born infants, and tended to have higher Distress scores than peak born infants (repeated‐measures ANOVA, P < 0.05). In addition, Distress scores were higher during maternal breeding than during the pre‐ and postbreeding phases. Finally, multiple regression (P < 0.05) indicated that while infant behavioral responsiveness predicted infant Positive Engagement during the acute challenge of maternal breeding, qualities of the mother–infant relationship predicted infant Distress. These data suggest that birth timing influences the patterns of mother–infant interactions during weaning and maternal breeding. Additionally, infant behavioral responsiveness and mother–infant relationship quality impact infant social engagement and affect expression, respectively. Am. J. Primatol. 74:734‐746, 2012. © 2012 Wiley Periodicals, Inc.     

Birth seasonality and interbirth interval of captive Rhinopithecus bieti

This study, which is based on 10 years of birth records, shows that black-and-white snub-nosed monkeys (Rhinopithecus bieti) in captivity display marked birth seasonality. The birth season starts in December and ends in June, with a peak from March to May, and a median birth date of April 10. More male infants than female ones are born in captivity. More males were born at the Kunming Institute of Zoology (KIZ) than at the Kunming Zoo (KZ). Of 17 interbirth intervals (IBIs), 29% were from females that had lost an infant at <1 year of age or experienced stillbirth, and 71% were from females whose infant survived more than 1 year. The mean IBI for the former group (428+/-SD 87 days) was significantly shorter than that for the latter group (706+/-71 days), in agreement with reports of other Colobine species. Infant mortality was lower in captivity than in the field, which may reflect the relatively stable food availability and climate in captivity compared to the harsh conditions in the wild.     

Male-infant relationships in semifree-ranging Barbary macaques (Macaca sylvanus) of affenberg salem/FRG: Testing the “male care” hypothesis

The infant-directed behavior of Barbary macaque males was analyzed in order to determine whether it is essential for an infant's survival during the first year and whether males interact selectively with closely related infants. Dyadic male-infant contacts were recorded in a large group of semifree-ranging Barbary macaques. Data collected during the first 12 weeks of life on each infant born in 1983 (n = 36) were analyzed. All adult and almost all subadult males established strong relationships with at least one infant. Almost two-thirds of the infants (22) had frequent contacts with one or several males. Males showed no preference for closely related infants. Sexual associations with an infant's mother during the preceding mating season had no significant effect. Natal males did not prefer infants of their own matrilineage. There was no evidence that contacts with males had a positive influence on infant survival or that other benefits to the infants resulted from these contacts. Instead, excessive carrying by males and females led to starvation of some very young infants and was a major cause of neonatal deaths in this population. Males interacted preferentially with infants that were born early in the birth season, had a high-ranking multiparous mother, and were male. Younger males established strong relationships with male infants only, while mother's rank was more important for older males. It is suggested that certain mothers prevented early contacts between their infants and males so that the observed preferences for certain infants were also a result of easier access to them. All results suggested that males interacted with infants for their own benefit.     

Deaths in a desert baboon troop

Over a 4-year period, three of 22 infants born in a desert-dwelling chacma baboon troop (Papio ursinus) survived to more than 6 months of age. Tick infestation and infant kidnapping by adult females were the main causes of infant death. The high neonatal mortality resulted in a rapid birth rate through a decrease in duration of interbirth intervals for mature females. There were more adult male deaths in the troop than adult female deaths. Males died from canine inflicted wounds sustained during fights.     

Life-history characteristics of a wild population of vervets (Cercopithecus aethiops sabaeus) in Barbados,West Indies

Life history data are presented for a population of vervets, Cercopithecusaethiops sabaeus, in Barbados, West Indies. The data were obtained from two habituated troops and from vervets captured during a large-scale trapping program. Individuals of known age from one troop were weighed periodically, and separate growth curves generated for males and females. The mean weight of captured adult females was 3.3 kg; that of adult males, 5.3 kg. The average age at sexual maturity is estimated at 34 months for females and 60 months for males. Vervets give birth throughout the year, but most infants are born between April and July. The average interbirth interval following a surviving infant is 11.8 months. The mortality of juveniles is heaviest between birth and 2 years of age and decreases thereafter. Males emigrate from their natal troops at sexual maturity and one incident of a juvenile female emigrating is reported.     

THE EFFECT OF BIRTH DATE ON FITNESS OF FEMALE DWARF PERCH,MICROMETRUS MINIMUS (PERCIFORMES: EMBIOTOCIDAE)

Lifetime reproductive success may vary considerably with birth date. I measured phenotypic selection on female birth date in a viviparous teleost fish (Embiotocidae: Micrometrus minimus) by sampling birth-date cohorts over time in Tomales Bay, California. Four episodes of selection were measured: survival from birth to first reproduction, reproductive success in the first breeding season, survival to second reproduction, and reproductive success in the second season. Birth date had a significant impact on fitness in the first two episodes. Early born females were more successful in their first breeding season than late born females (directional selection on birth date), but early born females were less likely to survive the period between birth and first reproduction, relative to females born in the middle of the season (stabilizing selection on birth date). The final two episodes of selection had no detectable effect on birth date. Because of the relationship between birth date and survival in the first year, overall selection on female birth date was stabilizing.     

Seasonality of births in Homo sapiens in pre-industrial Finland: maximisation of offspring survivorship?

We examined the seasonal variation in human birth and infant survival rates in pre-modern Finland. If survival probabilities of children born during different seasons of the year differ and if timing of reproduction has been affected by natural selection, periodic variation in environment could have led to reproduction during the season of best infant survival expectations. Significant seasonal variation in both birth rate and survival probability was found, but the monthly birth and survival rates of newborn were uncorrelated. Hence, if there was any tendency to maximise the reproductive success, increase in some other component of fitness than the infant survival was probably targeted. The effect of major holidays on the birth rate was proved to be notable, suggesting that although the basis for seasonal variation in birth rate was biological, sociocultural factors had an impact on the timing of reproduction in humans. The overall mortality of infant boys exceeded that of infant girls in all seasons. This difference was smallest during the time of best food supplies, indicating that the development of males was less buffered against environmental disturbances than that of females.     

Temporal Variation in Japanese Macaque Bodily Mass

We investigated the bodily mass of infants and postpartum adult females longitudinally in provisioned free-ranging Japanese macaque (Macaca fuscata) troops of the Takasakiyama Natural Zoo, Oita, Japan. We investigated whether the rate of mass change in postpartum adult females and infants is more strongly associated with season (or calendar date) as opposed to the length of time since delivery/birth. Focal adult females' postpartum mass ranged between 7 and 10 kg for a year after delivery. For postpartum adult females, calender date (season) influenced the rate of mass change more than the length of time since delivery did. Rate of mass change in postpartum adult females was high in October (autumn) and April and May (spring) and low between December and February (winter). This may reflect seasonality in energy and protein intake from natural foods. Infant mass increased steadily from birth. Mass of infants varied between individuals, some infants reached 2 kg by about 240 days of age, and others by about 400 days of age. It was unclear, however, whether the rate of mass change in infants was influenced more by age or calendar date (season). Differences in trends between adult females and infants may reflect, to some degree, differences in sources of energy intake, i.e. solid foods for adult females and suckling and solid foods for infants.     

Growth and developmental outcomes of three high-risk infant rhesus macaques (Macaca mulatta)

Infants classified as "high risk" are born with a greater chance of developing medical complications at birth, and may have cognitive and other developmental complications later in life. Very few reports exist regarding the survival and outcome of such infants in primate colonies. Here we present early growth and developmental data on three high-risk infant rhesus macaques (one female and two males) that were born either with intrauterine growth restriction (IUGR; born below the 1st birth weight percentile for gestational age) or extremely prematurely (at gestational days 128 and 140; mean full-term gestation=164 days). We compared the outcome of these infants with that of healthy controls born at term and found no gross developmental delays in these infants with respect to growth, neonatal reflex and motor skill development, early cognitive development, or social behavior. Neurological and cognitive assessments were compared in terms of both postnatal and gestational age. The survival of these infants was dependent on a 24-hr staffed nursery and a fluid protocol that catered to each high-risk infant's individual needs. When such measures are implemented, infants such as these have a good chance of survival and can serve as excellent models for high-risk human babies and their subsequent development.     

Sudden infant death syndrome and postneonatal mortality in immigrants in England and Wales.

To examine ethnic differences in postneonatal mortality and the incidence of sudden infant death in England and Wales during 1982-5 records were analysed, the mother''s country of birth being used to determine ethnic group. Postneonatal mortality was highest in infants of mothers born in Pakistan (6.4/1000 live births) followed by infants of mothers born in the Caribbean (4.5) and the United Kingdom and Republic of Ireland (4.1). Crude rates were lower in infants of mothers born in India (3.9/1000), east and west Africa (3.0), and Bangladesh (2.8) than in infants of mothers born in the United Kingdom despite less favourable birth weights. Mortality ratios standardised separately for maternal age, parity, and social class were significantly higher in infants of mothers born in Pakistan and lower in those of mothers born in Bangladesh. The ratio for infants of Caribbean mothers was significantly higher when adjusted for maternal age. Ratios for infants of Indian and east African mothers did not show significant differences after standardisation. An important finding was a low incidence of sudden infant death in infants of Asian origin. This was paralleled by lower mortality from respiratory causes. During 1975-85 postneonatal mortality in all immigrant groups except Pakistanis fell to a similar or lower rate than that in the United Kingdom group; Pakistanis showed a persistent excess. During 1984-5 several immigrant groups (from the Republic of Ireland, India, west Africa, and the Caribbean) recorded an increase in postneonatal mortality. Surveillance of postneonatal mortality among ethnic communities should be continued, and research is needed to identify the causes underlying the differences.     

Infant Development and Parental Care in Free-Ranging <Emphasis Type="Italic">Aotus azarai azarai</Emphasis> in Argentina

Studies of infant development and parental behavior in free-ranging owl monkeys have been constrained by their nocturnal habits. Taking advantage of the cathemeral activity pattern of Aotus azarai azarai in the Argentinean Chaco, we describe the development of a cohort of free-ranging infants born in an owl monkey population in Formosa Province. We observed 7 infants, whose birth dates are known to the nearest week, to record details of their development and care between October 1999 and March 2000. We collected 92 h of behavioral data in 76 sessions. The infants were almost never off the parents during the first 4 wk of life, and we observed no infant being transported by a nonadult. The parent carrying the infant traveled most frequently in the middle of the group, sometimes first, but rarely last. The mean duration of 33 nursing episodes is 69 sec. After nursing, the infant was more likely to return to the nonnursing adult than to remain with the mother suggesting that in owl monkeys the infant may be primarily attached to the adult male in the group. Infants began to explore, to manipulate and to consume solid foods during the second month. Our observations are comparable to ones on captive breeding groups of Colombian owl monkeys (Aotus lemurinus) and Bolivian owl monkeys (A. azarai boliviensis) under controlled conditions of temperature, illumination and food availability.     

Patterns of low birth weight in the Bengali newborns

This paper examines the distribution of low birth weight (2500 g or less) by gestation time, sex, maternal age, parity (birth order), socioeconomic conditions, and season of birth among 5117 single live births born to Bengali mothers at the Ramakrishna Mission Seva Pratisthan Hospital in Calcutta, India. Preterm infants have low birth weight significantly more often than their full term counterparts. Female infants have low birth weights significantly more often than male infants. The infants of poor mothers have lower birth weights in higher order births more often than infants of higher orders born to well-off mothers. Teenaged mothers produce low birth weight babies significantly more often than older mothers. Although the relationship is not significant, low birth weight infants occur more often among 1st and late born infants and less often among 2nd born infants. The season of birth is not significantly associated with birth weight. Less than 10% of low birth weight infants are pre-term, while the rest are full term. The great majority of low birth weight infants are small-for-gestational-age; the minority are small due to curtailed gestational age. The proportion of infants weighing less than 2001 g is only 9%; this figure tallies closely with earlier studies of India.     

Peer-rearing influences subsequent maternal behavior and infant survival in a newly formed herpes B-virus negative rhesus macaque group

The maternal behavior of primiparous rhesus macaques (Macaca mulatta), peer-reared since 1/2 years(s) of age as part of aHerpesvirus simiae (herpes B-virus) screening protocol, was examined and compared to a control group of conspecifics reared in their natal group. Infant survival was significantly higher in control groups as compared to the test group, a result attributed to the high incidence of infant kidnapping/abandonment in the test group. Among the test subjects, infant survival rate increased as the birth season progressed, thus it is possible that exposure to mothers/infants helped in the maternal success of those females who gave birth later in the season. Test group infants were touched by group members significantly more than the infants of control subjects, whereas these infants were groomed by their mothers and in a ventral position for a greater time relative to the infants of the test subjects. This study suggests that females, partially reared in peer groups, may be at early risk for maternal incompetence and consequent greater infant mortality, and that exposure to mother-infant dyads may augment the proficiency of maternal skills.     

Growth and development of infant giant pandas (Ailuropoda melanoleuca) at the Wolong Reserve,China

From 1991 to 1993 inclusive, seven infant giant pandas (Ailuropoda melanoleuca) were born at the China Conservation and Research Center for the Giant Panda. Average daily weight gain in the first 6 months for mother-reared infants (n = 5) was 71.3 g/day; for one partially mother-reared and partially hand-reared infant, 41.5 g/day; and for one completely hand-reared infant, 50.3 g/day. There was a significant difference in growth rates across the first 6 months in all methods of rearing. In addition, a comparison of growth rates across the three rearing methods showed significant differences in the first, second, third, fifth, and sixth months. Average daily body length increase for mother-reared infants was 4.1 mm/day; for partially mother-reared/partially hand-reared infants, 4.0 mm/day; and for the completely hand-reared infant, 2.8 mm/day. In mother-reared infants, body length increase during the first month was significantly greater than during the following months, and was slowest during the sixth month. At birth, infants were all pink in color with a light white coat of lanugo. Black pigmentation was first noted at 7–10 days of age, which was also the time that initial hair coat growth was seen. Eyes opened at 35–48 days of age. Ears opened at 31–50 days of age. Deciduous dentition was first seen at 82–121 days of age, while permanent dentition began to erupt at 350 days of age. © 1996 Wiley-Liss, Inc.     

Factors in the rejection and survival of captive cotton top tamarins (Saguinus oedipus)

Captive colonies of cotton top tamarins experience a high rate of rejection of infants within the 1st week of life. The rates of rejection and survival to maturity (2 or more years) among 659 live colony-born infants were correlated with rearing, birth group, litter size, season of birth, gender, origin of parents, experience of parents raising siblings, parity and age of parents, and experience of parent pairs. The most important factors associated with low rejection rates were family life and parental experience raising infants. Infants born into family groups or reared in families were rejected at a significantly lower rate. Rejection of infants whose sires were raised with siblings was significantly lower. Paternal experience was more important than maternal experience. Litter size had no effect on rejection of infants born to family groups, whereas, rejection of triplets was significantly higher than twins or singles among those born to parents alone. Rejection was significantly higher among primiparous births than multiparous birth. The combined experience of colony-born parents was not related to rejection if there were no sibling helpers in the cage at the time of birth. Rejection was significantly lower if sibling helpers were present. High survival of infants who were not rejected was correlated with rearing by or being born into family groups and higher parity and older age of the sires.     

Impact of Male Takeovers on Infant Deaths,Births and Conceptions in Cebus capucinus at Santa Rosa,Costa Rica

Male takeovers are associated with infant wounding and death in 3 of 4 capuchin species. In this paper, I analyze the effects of male takeovers on infant mortality and the subsequent conceptions and interbirth intervals of their mothers over an 18-yr period and test predictions of the sexual selection model of infanticide for white-faced capuchins, (Cebus capucinus). Major findings are that infants are significantly more likely to die in the 3- and 12-mo periods following a takeover than in times of peace and that a female whose infant dies experiences a significantly shorter interbirth interval before her next infant is born than she would have had the former infant survived. In the vast majority of cases, the invading males become resident in the group and are present during the subsequent conceptions of the females in the group. However, overall conception rates do not rise significantly in the year after a takeover, there is no relationship between the age of the infant at death and the length of the mother's subsequent interbirth interval, and it is not yet clear if male infants are preferentially targeted by invading males. Most takeovers occur during the 6-mo dry season and most conceptions occur in the wet season, 3–6 mo later. My findings support the major predictions of the sexual selection model of infanticide in primates and demonstrate that male takeovers of social groups have substantial effects on infant survival and maternal parturition patterns in Cebus capucinus.     

Life history traits, maternal behavior and infant development of blue-eyed black lemurs (Eulemur flavifrons)

An understanding of recruitment is important for estimating population growth and viability, and their implications for conservation. We present the first results regarding the life history, maternal behavior and infant development of the critically endangered blue-eyed black lemur (Eulemur flavifrons) of Madagascar. The species breeds seasonally, with births occurring at the end of the dry season, between late August and October. Over two successive birth seasons in 2006 and 2007, we observed a total of 13 lactating females and 22 infants from six groups. We inferred age at first reproduction as 3 years, and calculated the birth rate as 1.0 infant per female per year with a mean inter-birth interval of 358 ± 24.81 days (319-410 days). Infants spent the first 3 weeks of life constantly with their mothers; locomotor independence and ingestion of solid food began at week 10, and the infants were weaned by week 25. After week 28, infants spent less than 20% of their time in contact with their mothers. Over the study period infant mortality was 22.7%, with predation and sickness observed as causes. Our results suggest that overall recruitment is relatively slow, which has implications for the species' survival, particularly given their restricted and threatened habitat.