A study recently published in the Applied Animal Behaviour Science journal has found that the noise and flash photography of zoo visitors make Edinburgh Zoo's chimpanzees anxious.

The study, in which researchers from Stirling, Cambridge and York universities observed a troop of chimpanzees held captive at Edinburgh Zoo in 2014 and 2015, has raised concerns over the well-being of primates in zoos.

Incidents of children screaming were found to increase the likelihood of the chimpanzees yawning, whereas flash photography was found to increase displays of self-scratching by the chimpanzees. In non-human primates, yawning and self-scratching are recognised as indicators of anxiety and stress.

As well as this, the study found that one factor of the animals' captive environment that contributed to increases in the chimpanzees' displacement behaviours was the length of time between feeding events. In the wild, chimpanzees spend an average of 6.68 hours per day foraging for food or eating. In zoos, however, this time is vastly reduced and there are often long time periods between feeds by keepers. The study concluded that 'when the chimpanzees have to wait longer to eat they are more likely to yawn.'

Sam Threadgill, the Director of Freedom for Animals commented; 

This study provides further evidence that zoos cannot provide an adequate environment for those held captive within them. Animals held in zoos often suffer from severe boredom and distress caused by the totally artificial and unsuitable surroundings that they are forced to live in.

Increases in visitor numbers also caused the chimpanzees to become stressed and display displacement behaviours. The Budongo Trail exhibit in which the primates live is visited by around 800,000 visitors every year, meaning that the anxiety caused to the chimpanzees is considerable.

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