and behavioral patterns of callitrichids so that they can diagnose potential problems from behavioral observations. Familiarity of the monkeys with their caregivers is extremely valuable, particularly in breeding colonies, because parents with newborn infants are easily alarmed by unfamiliar humans and if so alarmed might neglect or attack their babies.
Capturing should be avoided as much as possible. Clear discriminative stimuli, such as different-color coats or uniforms, worn when handling is necessary can help monkeys to predict and discriminate the handling event and thus prevent generalization to caregivers performing routine colony tasks. The presence of a familiar technician who does not participate in the capture itself might be helpful in calming animals that have been captured.
If handling is necessary, the animal in question should first be removed from the colony room. The distress vocalizations of monkeys that are caught and handled tend to arouse the entire colony room and in some species can cause prolonged symptoms of stress, such as diarrhea. Frequent handling might be avoided in some species, such as the common marmoset, by training the animals to accept medications with rewards of preferred food (Hearn 1983). However, tamarins appear to be more excitable and less amenable to training than marmosets. Responses can differ between individual animals, so various catching methods, such as locking the animals in the nest box and removing them from there or using a small net, are useful. A net might be useful for these animals because the animals tend to associate being handled with the net rather than with the person who catches them. The use of nets, however, should be undertaken with caution because animals can be injured by the hoops and handles of nets or by becoming entangled in the nets themselves.
Veterinarians should be experienced in handling small animals that have high metabolic rates. Because of their high metabolism, animals that become sick can deteriorate quickly. An animal can appear in good health in the morning, show signs of sluggishness or ataxia in the afternoon, and die by the following morning. Animal care personnel should be trained to monitor behavior for signs of illness. Signs include chronic piloerection, sluggishness, ataxia, diarrhea, lack of appetite, dull and sunken eyes, weight loss, and changes in routine behavior. They are usually noticeable only by human observers who are familiar with the individual monkey.
Marmosets and tamarins can be trained to step on the platforms of remote reading scales, and regular weighings are possible. Technicians can monitor the physical well-being of the animals through these weights, and interventions can be undertaken for animals that show substantial loss of weight. Therefore, well-trained and concerned animal technicians are invaluable to the veterinarian. They can alert the veterinarian to health problems or behavioral problems (for ex-