Animal testing on non-human primates between the monkeys natural behaviors versus the behaviors expressed by the diazepam induced monkeys in thirteen different locations inside the maze. Scientist Barros and his colleagues created this model to allow the monkeys to roam a less confined environment and slightly eliminate outside factors that may induce stress. Many of the best-known allegations of abuse made by animal protection or animal rights groups against animal-testing facilities involve NHPs. The so-called "pit of despair" was used in experiments conducted on rhesus macaque monkeys during the 1970s by American comparative psychologist Harry Harlow at the University of Wisconsin–Madison.<ref name="Blum1994/95">Blum, Deborah. "The Monkey
Macaque in check. For example, if 80% of females are sterilized every five years, or 50% every two years, it could effectively reduce the population. Other control strategies include planting specific trees to provide protection to native birds from macaque predation, live trapping, and the vaccine Porcine Zona Pellucida (PZP), which causes infertility in females Macaques have a very intricate social structure and hierarchy. If a macaque of a lower level in the social chain has eaten berries and none are left for a higher-level macaque, then the one higher in status can, within this social organization, remove the berries from