In the wild, marmosets are free to fully express their whole range of physical and behavioural needs, to explore and exploit their environment and interact socially, all of which are essential for their health and psychological well-being. In the stark confines of the laboratory these inquisitive and active animals are reduced to the tedious routine of captivity.

"I could say I know marmosets & I know they're stressed... Think of it though, they're water-deprived, they get a diet of pellets, they get no forage mix... Basically they're just stuck in an aluminium box."
Senior Animal Technician admitting to the desperately sad and deprived life of the marmosets

The Wild

The common marmoset (Callithrix jacchus) belongs to the Callitrichidae family. The Callitrichids are all small, South American primates. In the wild the natural habitats of the marmoset are the jungles, swamp forests and tree plantations of Brazil. They are almost completely arboreal, living in the trees virtually all the time.

Marmosets are very sensitive and easily stressed, particularly when caught and forcibly restrained in order to be tagged. In litters with more than two babies, the only real chance of survival for the 'extra' babies is human intervention. If this is lacking then the babies will inevitably die.

Marmosets are highly intelligent, sensitive and social animals. They can live for up to 20 years. The normal family group can range from 3-20 members, comprising parents, sub-adult and infant offspring. They form close-knit family ties and both parents and the older offspring share the responsibility of caring for and carrying infants.

Marmosets are territorial. They mark their territory, which can cover more than 20 acres, with scent and will defend it against intruders. A marmoset will typically travel between 1-2 km a day within this area. When threatened, their instinct is to flee upwards into the trees. They are omnivorous, enjoying a mixed diet of fruit, leaves, insects and large amounts of tree gums. Common marmosets eat more gum than any other marmoset (15% of total diet). To supply their dietary needs they require a complex and diverse environment which must be sufficiently large to contain enough tree species for the group. Typically this requires at least 50 gum producing trees.

The Laboratory

It is impossible to recreate the rich diversity of their forest home in any laboratory, but here at Cambridge University, the BUAV uncovered a world where marmosets were cruelly deprived of the space, social contact, enrichment, diet and complex environment necessary to satisfy their biological, psychological and behavioural needs.

Hundreds of marmosets were kept in small rooms with no natural light in barren, metal cages devoid of any serious attempt to provide an enriching and stimulating environment. Many monkeys were stacked on top of each other in two tier cages. For arboreal monkeys to be kept at ground level where they cannot flee upwards is likely to be extremely stressful. Other monkeys were even caged on their own. Both types of caging actually contradict accepted best practice in the field (The Universities' Federation for Animal Welfare - UFAW). Some monkeys displayed abnormal, stereotypical behaviour, circling round and round the cage.

Furthermore, the UK Government's own Code of Practice that covers the housing and care of laboratory animals states: "Size, shape and fittings of pens and cages should be designed to meet the physiological and behavioural needs of the animals" (Section 3.21)

"...Primates have high intelligence, most have arboreal habits and all need complex, stimulating environments" (Section 3.43)

Fights, which are rare in the wild, did break out in the restricted confines of the cages. Wounds and injuries occurred and, as a result, some families had to be split up prematurely.

The monkeys were given names and a number by staff. The names were often tastelessly fanciful and included those of celebrities or favourite holiday destinations; a sickening twist considering the fate of these poor animals. Breeding monkeys were held in family groups. Marmosets can produce two litters of babies a year and naturally produce twins which is one of the reasons they are so attractive to researchers. However, in captivity, the females can produce an unusually large number of triplets or more but are physically unable to feed this number. The babies' only real chance of survival is human intervention. However, here at Cambridge University hand rearing was not part of the husbandry routine and babies were often left to die or were killed if seen to be non-thriving. At around 12 months old the young marmosets were caught and tagged and a chain was put around their neck. Many of the animals found this to be extremely distressing as it often involved the marmosets being chased around their cages and then forcibly restrained.

Some females at Cambridge University had had up to 21 litters. However, once reproductivity began to wane, breeding pairs could be killed. This could happen at only 10 years old. Some pregnant females were also subject to an experimental procedure - a hysterectomy where their foetus was removed and used as 'donor' tissue for brain grafting experiments on other monkeys.

Many of the experimental monkeys were deprived of water for periods of time and kept on a food restrictive diet. In the wild, marmosets spend up to 60% of their day foraging for food. Tree gum, an important part of their diet in the wild, was not given to the experimental monkeys. There were just three animal technicians to care for all 400-500 marmosets. Duties included food preparation, feeding, watering, cleaning out cages and rooms, individual health checks and record keeping. The colony consisted of many animals who had been brain damaged resulting in physical and mental disabilities as well as those who were injured and sick. At weekends and public holidays, there was only one technician on duty who was expected to feed and check all the marmosets within approximately three hours. Surely these working hours were incompatible with good husbandry?

At Cambridge University there were too many monkeys kept in inadequate caging with too few staff to care for them. With so many monkeys, individual care and attention must have obviously been lacking.

See for yourself some of the actual secret footage as filmed by our investigator.

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