Feeding wild monkeys may pose risk to their health by making them larger in size, more susceptible to diseases and stressed, a new study on macaques in Morocco has found.
Researchers led by Laetitia Marechal from University of Roehampton in the UK compared the health of two groups of wild Barbary macaques in Morocco.
One group spent nearly 50 per cent of their feeding activity eating food provided by humans. The other group rarely encountered tourists and instead relied on natural food resources, researchers said.
The macaques which ate food from tourists were found to have poorer quality fur, with some patches of alopecia, and also suffered from higher levels of stress hormones compared with the other group, they said.
All the females in the non-fed group gave birth, but only a third of females in the groups of Barbary macaques frequently fed by tourists had babies, researchers said.
The monkeys which relied on natural food were observed to only suffer one incident of a stomach upset, while the group which received large amounts of food from tourists had 32 bouts of illness, they said.
The study also found that the effects of feeding by tourists were different depending on sex. While males did not differ between groups in body size and fur quality, the females fed by tourists had larger body sizes, but better coat quality, researchers said.
However, the males suffered more from alopecia and higher stress levels, they said.
"Barbary macaques are an endangered species and recently tourism was proposed as a potential tool for the conservation of this species in Morocco," said Marechal, currently with University of Lincoln in the UK.
"But such tourism is currently unregulated, and feeding is a common practice; therefore regulating tourist provisioning may improve animal welfare," she said.
Researchers assessed the primates' health using a range of non-invasive measures, such as birth and survival rates, the quality of their fur, body size, occurrence of injury and disease, and stress hormone levels in faecal samples.
The findings support previous research which indicates that wildlife tourism, and particularly so-called 'tourist provisioning', has negative impacts on the health of wild animals, researchers said.
The findings were published in the journal PLOS ONE.