Reproduction Breeding & Handrearing Marmosets & Tamarins. (December 01, 2007) Reproduction & Handrearing of Marmoset & Tamarins.
Marmosets and Tamarins have a rapid reproductive rate. They typically give birth to twins and there is no period of lactational anoestrus. A post-partum oestrus occurs within 10 days of parturition and conception rate at this oestrus is high. Some breeding females may be almost constantly pregnant. Gestation varies between Species. The lion tamarins have the shortest gestation at 128 days, while most other Species are reported to have a gestation of around 145 days. Cotton top tamarins have the longest known gestation at 183 days. Infant care is shared among group members. In most species other group members may participate in infant care by carrying the Infant from day l or 2. Contrary to earlier reports this is also true for lion tamarins. Goeldi's monkeys, on the other hand, are the exception to this with shared infant care not taking place until week three. In captivity the Callitrichidae are effectively monogamous. The dominant pair, who In most groups will be the parents of all other group members, suppress other adults within the group from breeding. This ensures that only the dominant pair breed, and generally means that inbreeding does not occur within groups. Rarely, however, incestuous matings and departures from monogamy occur. In the wild, a much more flexible reproductive strategy is apparent in most species for which good information is available
These points are discussed in more detail below.
TWINNING
The marmosets and tamarins are unique among simians in their habit of twinning. While single infants and triplets are not uncommon among marmosets and tamarins, the most frequent litter size is two. Occasionally, quadruplet births have occurred, but there are no reports of all four infants being born alive in Zoos or in the wild. The incidence of triplets has been reported to increase with time in captive colonies of and may relate to a high protein diet in captivity. It is unusual for all three infants of a triplet litter to be parent-reared in captivity. Recently, evidence from DNA studies has provided good evidence that triplets have been reared to independence in a wild group of jacchus. Callitrichid twins are dizygotic and share the same placenta and amniotic sac. Some considerable discussion has centred around whether twinning is a primitive feature that has been retained, or a derived feature, maintained that twinning was a primitive feature, while most other authorities have considered it derived, citing the highly specialised placentation, simplex uterus, and number of teats as evidence.
Reproductive strategies
Care must be taken to distinguish between social group structure and mating relationships when discussing reproductive strategies. The presence in a group of more than one adult of either sex does not necessarily indicate that they are all reproductively active. They may, for instance, be non-reproductive mature offspring of the breeding male or female. In captivity, mature offspring may remain in a stable group and yet not enter a breeding relationship with their parents or siblings, as they are reproductively suppressed. The fact that a female may mate with more than one male is also not conclusive evidence of a polyandrous breeding system, although it is obviously suggestive of this. Only when paternity of offspring can be established will the breeding system be understood fully. In fact, in spite of the many reports of group structure indicating that there may be more than one breeding pair in a wild callitrichid group, only a few studies have actually reported seeing females mated by more than one male,even fewer studies have reported more than one breeding female in a social group at the same time. It is, however, not surprising that there is a paucity of data from wild groups. As pointed out, the marmosets and tamarins are small difficult to habituate to the presence of observers, and mating may last only a few seconds. Studies have shown. however, that even within a species the reproductive strategy may vary. Infant rearing is discussed more fully below.
Reproductive suppression.
Reproductive suppression of subordinate females among captive callitrichid groups is a well-documented phenomenon In C. jacchus. hormonal studies of females in peer groups have shown that the behaviourally dominant female is the only female to undergo normal ovulatory cycles. In nuclear family groups, it has also been shown that daughters do not exhibit ovulatory cycles and are therefore also suppressed in the three species some daughters do ovulate although they do not cycle regularly while still in their natal group and rarely this also occurs in S. oedipus. In Leontopithecus. on the other hand, daughters may undergo normal ovulatory cycles within their natal groups.Young females are often subject to severe aggression from their mother when they mature and are thus prevented from breeding through behavioural rather than physiological means. Physiological suppression of female cycles is by no means absolute. There are several instances of breakdown of suppression to suggest that something other than dominance is operating to maintain reproductive suppression of daughters within their natal groups and effectively acts as an inbreeding avoidance mechanism. Incestuous matings resulting in pregnancy do occur rarely in established breeding groups. If one of the parents of a group is removed it has been reported that in time suppression will eventually cease to be effective and incestuous breeding occurs. If a breeding male is removed, or dies, and replaced in a group with the surviving mother and her daughters, it should be expected that the male will breed with the daughters as well as the mother. While the group may remain stable for some time with more than one breeding female, it should be expected that eventually aggression between the females will occur resulting in the expulsion of one from the group.
Infant care patterns among the Callitrichidae
It has been suggested that twinning has major consequences for the breeding female among the Callitrichidae. Not only must the female carry twin foetuses through pregnancy, she must also rear them to independence. It has been showed that in captive cotton-top tamarins, energy intake by the female increased during lactation, and is showed in the same species that, when lactating, feeding rates of the female increased to a peak during the second month following birth, and only declined when infants began to receive food from other group members. Researchers have suggested that this is the reason for the communal or cooperative pattern of infant care seen among the callitrichids in which several, if not all, group members are involved in infant care and provision of food Recent reviewers of the social and reproductive systems of the marmosets and tamarins have attempted to interpret the inter-relationship between the sex ratio of wild groups, the mating systems that they exhibit and the role of helpers providing extra-maternal care of the offspring. These communal breeding systems have been referred to as 'cooperative polyandry'or 'functional polyandry. The variability shown both within and between callitrichid breeding systems is becoming increasingly apparent. For instance, differences have been highlighted between breeding systems of the marmosets and tamarins that probably relate to fundamental differerances in their ecology It is unlikely, therefore that such generalisations about the callitrichid breeding systems will be sustainable in the future.
Implications for captive management
Marmosets and tamarins breed within a tight cohesive social unit in captivity. For successful breeding stress needs to be minimised and groups should be maintained in their usual enclosure and with their usual group structure. It is vital, for instance, that breeding females are not separated from their groups prior to, or at parturition under normal circumstances. Mating is rarely seen, particularly within established groups of callitrichids. Mating occurs during pregnancy and outside the ovulatory period of the non-pregnant cycle, and hence conception dates are rarely known. As a rule of thumb, pregnancy is detectable visually about two months prior to parturition if it is possible to get a clear view of the abdomen of the breeding female prior to any feeding during the day. At one month prior to parturition abdominal swelling is usually clearly visible. Not all pregnancies can be detected visually and gaining reliable estimates of parturition dates is difficult based on female size, but this is nevertheless a useful indicator of when parturition may occur .Births almost invariably occur overnight. Many zoos put soft substrate of woodwool or similar material on the cage floor in preparation for parturition in case of falls. Occasionally births occur during the day, but this is usually an indication of a problem, although pied tarnarins have been often observed giving birth in the late afternoon rather than overnight. In some species there is a high rate of failure to rear young. In the event of infants being abandoned by the parents all possible attempts must be made to reintroduce them and induce parent rearing. If this fails, however, hand rearing may be attempted. Dead and mutilated infants are reported relatively frequently and may be due to several reasons. Stress at the time of parturition may induce infanticide and underlines the importance of reducing stress for these animals particularly at the perinatal period. Behaviourally incompetent parents may kill or injure infants. Overzealous grooming by a parent or sibling may result in injury to infants and should be monitored carefully. Landmarks in infant development are variable depending on many circumstances such as species, history of the family group (first time mothers are likely to show later landmarks than established breeding groups).Iinfants are carried for about two to three weeks, after which time they may, be seen taking tentative steps and mouthing food. By six weeks of age most are independent of the parents and weaning is well under way. By twelve weeks they are weaned and capable of independent existence. As reported in the section on social behaviour , infant care has a largely learnt component. It is vital that young are left with their natal group to experience and participate in infant rearing in order to become competent parents themselves.
Hand Rearing
The need to hand rear may be necessary for a variety of reasons -rejection by the parents, ill health of the mother, weakness of the offspring or a triplet birth. Careful consideration must be given as hand rearing requires a great deal of time and commitment. Unless the individuals are of genetic importance subsequent problems in hand-reared adults may be undesirable. With careful re-introduction they can, and do, breed normally, but can develop behavioural abnormalities and may become extremely aggressive towards their keepers. Fostering may be considered as a possible alternative to hand-rearing if a suitable foster mother is available. If rejected, offspring may be found on the floor or the adults will be agitated, pulling them, trying to rub them off against perches and wire and in some cases biting them severely.Every effort should be made to keep the baby within the group. Sometimes it is possible to remove the infant and feed it and try returning it to the group later or the next day but it is important to monitor the situation closely. If the offspring are being cared for but receiving no milk they will be restless. climbing over the adults continuously. As they become weaker they will hang from around the legs or the base of the tail of the parent. The infant's tail normally held coiled, may be seen extended and limp. Contented babies, when very young, sleep most of the time. When not suckling they will cling tightly around the neck or shoulders of the parent, in triplet births one baby usually dies. In several species three young have been reared but this is rare. Sometimes one dies very quickly but they may all die after some days as all three may not have received enough nutrition. When removing a triplet the temptation is to take the smallest one, but this one has a better chance with its mother than if hand reared. The largest, strongest baby will respond better to hand rearing.You may consider hand rearing two of triplets as they will then grow with each other's company and may become less imprinted. Several institutions, particularly laboratories, have successfully used a system of alternating which of triplets receives food, taking a different infant each day. In zoos animals tend to be handled less than in laboratories and potential the benefit of alternating between the triplets need to be weighed carefully against the stress to the carriers of the extra handling involved.
Physical condition of infants
An incubator is the best source of warmth. Heat lamps are not suitable, the heat is too intense and will dehydrate the babies. If an incubator is not available hot water bottles are good, but use caution and wrap them in several layers of towelling. Small babies die very quickly if too hot. 26.5°C-29°C (80-85°F) is ideal. Heated plant propagators are useful for older youngsters but are not usually warm enough for newborns. In a real emergency a domestic iron on the lowest setting wrapped in towelling in a box can be used as a heat source. Should the baby be hypotheimic when you remove it, you can raise its body temperature gently by holding it against your own body or holding it in your hand in a bath of warm water. Hot water bottles do have one advantage in being easily transportable. They can be placed in a basket or carrier if you have to take the young ones with you anywhere. The baby will need something to cling to, a small toy or, if this is not available, a couple of thick socks rolled together will do.
Feeding regime.
A syringe with a small teat on the end is the best thing for feeding. Dolls ' bottles are usually too large and glass ones are awkward to use. Syringes also have the advantage of being calibrated so the amount of each feed can be recorded. There are many accounts of milk formula and various additives but experience has shown that a good quality milk substitute for human babies is quite adequate without additional vitamins etc.Start by feeding the baby every 2 hours. The milk must be warmed to blood temperature, gauge this by holding the syringe against your cheek or wrist. Babies will not take milk that is too hot or too cold. It is best to wait a little while if they have been taken directly from the parents, as they may be distressed and will accept an artificial teat more readily if hungry. Hold the baby in an upright position to feed it,not lying on its back. This will help stop milk being inhaled and going into the lungs which can lead to pneumonia. If they sneeze it out of'the nose dab it with tissue to prevent it being inhaled. Introduce the teat to the mouth and, if the baby sucks the teat immediately, release the milk slowly the infant does not suck at the teat try putting a drop on the lips to see if the baby will lick it. The first feed can be of just glucose or honey and water to start the system gently, the second feed diluted milk and thereafter as per the mixing instructions. The baby may take very small amounts at first, O.5ml being average for the first few days. Feed only when the baby is hungry and sucking vigorously, encouraging it to keep taking more milk will be fatal. Babies will not die of being slightly underfed, but overfeeding will kill them. As the volume of the feeds increases the frequency can be reduced; 3 hourly 2nd week, 4 hourly 3rd week, etc. Babies will be very hungry at some feeds, less at others, but this is quite normal. After each feed stimulate the baby to urinate and defecate by gently rubbing the anus and genitals with some tissue or cotton wool which should be moistened with warm water. The first motion is normally very thick and dark after which they will be pale yellow. Should the baby become sore around the base of the tail use a little baby cream. After two weeks the baby will not need feeding at night- 6.00am -12.00pm being sufficient. After 4 weeks introduce very small amounts of cereal-based infant food to the milk, gradually increasing it during weeks 5 -6. By week 4 the baby will start taking soft banana or pear from your fingers. At this stage start leaving the baby with a small bowl of finely chopped food. By 12 weeks the baby will be fully weaned but may still appreciate some baby cereal in a bowl, particularly if this is not part of your normal adult feeding regime.
Monitoring progress
Weighing the babies daily and keeping a record of their weight gain is important. The weight should increase steadily, though not necessarily daily (a little weight loss may occur in the first couple of days). If there is gradual weight loss while they are still being fed milk consult your vet or seek further guidance. When the babies begin to wean and you start withholding bottle feeds a slight weight loss is normal. Minor digestive problems can occur. Constipation if the babies have not defecated after a couple of feeds, might be remedied by replacing a milk feed with glucose and water. Using water that has had a handful of rice boiled in it to make up the milk feed may help diarrhoea. The starch in the rice has a binding effect. If diarrhoea is severe and persistent feed the baby an electrolyte solution to ensure it does not dehydrate. If this is done for a couple of feeds it may solve the problem otherwise consult your vet. Be very cautious when using kaolin based remedies as they can cause intestinal blockage.
Reintroduction
Reintroduction should be started as soon as possible, contact with the rest of the natal group is very important. Ideally during the day the infants should be kept within sight, sound and smell of the group, preferably in their container within the enclosure. Once the infants are mobile they should be released for short periods, gradually increasing until they are fully integrated. All interactions should be observed initially. If it is not possible to reintroduce infants to their family, mixing them with a single animal of any callitrichid species can be successful and is preferable to isolation. Click here to return to the Your Articles & Stories page
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