Primates are always great crowd pleasers at any zoo. The mere sight of a hairy chimpanzee is enough to cause human adults and children to act like fools in the hope of getting a response from their genetic cousins. By contrast, keeping the animals themselves interested in zoo life takes careful planning. "Aside from feeding them we try to keep them interested," says Noa Danin, chief monkey keeper at the Jerusalem Biblical Zoo. With over 100 primates from a variety of species in her care Danin has plenty to keep her busy. Every morning the chimpanzees and mandrills go through a medical check-up to monitor their health. The chimps have developed a remarkable vocabulary and respond well to instructions to bare their teeth or to offer a hand inspection. Nonetheless, not everyone opts for the morning physical every day. The chimps have their moods and sometimes it is best to leave a petulant monkey to itself. "It's like working with children," Danin sighs. In the chimpanzee enclosure, leaves and twigs lie scattered across the floor of the exhibit, but the litter is deliberate. Chimps take anything that comes to hand for use as primitive tools to hunt for food. Chimps like to snack on termites that they "fish" out of termite hills by poking a twig into a hole. Keeping a termite hill in Jerusalem is impractical, so instead the chimps have a honey and water stand. Aside from the honey-hill, the chimps also have a push-button water fountain and a fruit machine attached to a wall. The latter is filled with fresh fruit that can only be removed by poking sticks through holes in its side. To further improve the monkeys' routine, keepers do something that would drive their human visitors up the wall: They move the furniture around. The chimp exhibit has various logs and ropes for the chimps to hang around on, and by moving the pieces around the chimps get to explore a little bit without leaving home. Next door are the mandrills, which require a different approach. Mandrills (which are actually classified as apes, not monkeys), are known for their brightly colored faces and rumps. As a general rule, they are not as violent as their chimp cousins and that allows keepers to be more creative with their toys. A large rope bag filled with fresh corn and hay hung in the middle of the exhibit is like having the circus come to town. The mandrills will spend several days trying to pull the vegetables out - by contrast, the chimps would just tear it to bits. The mandrills' more delicate nature is also apparent in how they view the world. Whereas chimpanzees will stare you in the eye, mandrills give side-long glances and look away if caught in the act. All primates have a natural suspicion of change and are very wary of new interior d cor. Danin explains that they fear new things and take time to get used to changes. However, this fear is beneficial and relates to the natural fear of predators in the wild. In captivity without this restlessness the animals would become bored and disinterested. Monkeys are very social animals and spend a lot of time building relationships. Sharing food, playing together and grooming is all part of a complex and intriguing social structure. The careful inspection of each others' hairy bodies that is often mistaken as a search for lice is in fact grooming. Danin explains that grooming is the monkeys' way of connecting with each other. Mothers and children bond over a good groom and courting pairs will run their fingers through each other's hair in romantic liaisons. For all primates, the most interesting pastime is caring for their children, and when the next best entertainment is poking twigs into a pot of honey, the monkeys are eager to reproduce. As a general rule monkeys enjoy "open relationships" and each male might father many sons and daughters from many females. For that reason the children tend to stay close to their mothers and this bond lasts a lifetime. The constant interest in making babies is a dilemma for the zoo: On the one hand infants bring life and joy to the monkey groups; on the other hand there is only so much room in each exhibit. As a compromise the zoo tries to limit reproduction by encouraging family planning methods. Since distributing condoms to the males would be wishful thinking, keepers administer birth control pills to the females instead. This measure has mixed success among the different primate species and the excess monkeys are sent off to good homes in other zoos. Visitors hoping to view the monkeys should do so before winter sets in. Monkeys spend most of the winter in the indoor section of their territory enjoying the heating. In the past even the curious appearance of snow could barely tempt the chimps to investigate. "Chimps are the biggest cowards of all the monkeys and the boy chimps are the biggest cowards of them all," Danin says.