Subscribe now

Life

City slicker monkeys are overweight and have high cholesterol

By Karl Gruber

21 July 2016

Close up of a white-footed tamarin

People in Medellín enjoy feeding the local white-footed tamarins

Thomas Marent/Minden Pictures

City slicker monkeys have it easy – but with their newfound lifestyle come health concerns.

Many white-footed tamarins seem to have been only too happy to change scenery and jump from a pristine forest into a concrete jungle.

“This species is the true native of the city,” says Iván Dario Soto, a conservation biologist from the University of Antioquia in Medellín, Colombia. “It was first described in 1876 in what is now the city of Medellin, but it was probably already there thousands of years ago. Settlers came and built a city and the monkeys just stayed around.”

Nowadays the monkeys seem to enjoy a life of easy food and few worries, bar traffic and occasional lethal shocks from power lines.

“There are no predators, and fruit trees like mangoes and guavas are quite common in urban forest patches, so tamarins probably don’t have to move as much as rural tamarins,” says Soto. “They are also a very charismatic species and people have fun feeding them things like cane sugar, cookies, marshmallows and bananas.”

But city life may have its downsides.

Soto’s team compared the health of 16 adult tamarinds (Saguinus leucopus) living in small forest patches in the city with 20 individuals in rainforests near rural areas. They trapped the monkeys several times over a two-year period, measured them and collected blood and faecal samples.

“The tamarins in the city were overweight, showed a 38 per cent increase in the levels of cholesterol, as well as a significantly larger body mass, compared with tamarins from rural areas,” says Soto.

Sheltered from parasites

It wasn’t all bad news, it seems. Urban tamarins had fewer parasites than their country cousins, which hosted 10 worm and protozoan species in all.

Soto is not sure why this is the case but he speculates that the urban population is sheltered from typical sources of parasites. “Forest patches in the city are isolated by roads and buildings. Also, parasite transmission frequently requires reservoir species and vectors that are unavailable in the city,” says Soto.

The apparent lack of parasites could simply reflect a sampling bias, though, according to Romari Martinez at the State University of Santa Cruz in Ilhéus, Brazil. “We would expect not less parasites but a different parasite load in urban primates,” he says, such as those found in city-dwelling species like foxes or bats.

“Despite the apparent fragmentation of the available forest patches, primates in cities use artificial connectors such as electricity or phone cables or transit through orchards and gardens from one patch of forest to another and are in constant interaction with other urban species,” he says.

Overall, the findings suggest that tamarins are good at adapting to urban environments, despite a small cost, says Robert Young, a conservation biologist from the University of Salford in the UK.

Whether the increased weight and cholesterol  have long-term consequences remains to be seen.  “It would be interesting to know the long-term effects of city living on longevity and reproduction in this species,” Young adds.

Journal reference: American Journal of Primatology, DOI: 10.1002/ajp.22581

Read more: Wildlife in the big bad city; New Urbanist: Our infrastructure is expanding to include animals

 

Topics:

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

Sign up