Primatology.net

A new study has changed the lives of seven mandrills for the better at England’s Chester Zoo. With the help of zoo staff, Durham University researchers found that placing shrubs between the glass enclosure and the visitor’s area reduced stress levels (as seen through aberrant behaviors) and increased natural behaviors.

Examples provided:

• approaching the glass
  • 54% decrease

• climbing and eating
  • 13% increase

• playing and grooming each other
  • 16% increase

Dr. Jan de Ruiter, Department of Anthropology, Durham University:

“We initially found some levels of stress among the mandrills. Their behaviour showed signs of anxiety and social tension. Visitors can further aggravate this stress as some people interpret the mandrills’ behaviour as amusing and start mimicking them.”

“As soon as the shrubs were positioned, we noticed an immediate improvement in the welfare of the mandrills, who displayed significantly less anti social behaviour. The botanical display also adds to the visitor experience as they gain a more natural impression of the type of environment in which the mandrills would be living in the wild in Africa.”

Makes sense doesn’t it?

As for visitors further aggravating the stress… as I’m sure many of us can, I can certainly vouch for that. Spending months observing behavior in the Monkey House at the Bronx Zoo, opened my eyes to the insensitivity of some individuals who feel it is acceptable to bang on the glass enclosure, yell at the animals, and egg them on in an infinite number of ways. While shrubbery won’t stop some people from being themselves, it sounds like it’s successfully keeping the distance and making life a little calmer for the mandrills. Excellent news.

Dr. Sonya Hill, Research Officer at Chester Zoo:

“This study shows that by measuring the behaviour of animals in their habitats, whether they be in the wild or in a zoo, we can understand their needs and preferences better. In this way, researchers can ‘ask’ the animals what they want. Zoos can then provide enclosures that aim to meet these needs and maintain good animal welfare. It is important to remember that life in the wild is not stress-free either, with factors such as predation, competition for food, and disease or injury, and as we learn more about each species we can understand what behavioural strategies they use to cope with their environment.”

The effort of the researchers has been recognized by UFAW (Universities Federation for Animal Welfare) and honored with the Wild Animal Welfare Award. The money awarded will be used for further animal welfare research at Chester Zoo.

In almost one year of blogging here, we haven’t yet covered how the study of biophysics intersects with primatology. (Update: I realized I kinda lied, I forgot about this post on gibbon gait. Oops.)

Biophysics, in a sense, is the study of the form and function of bodies, and is formally defined as the application of the laws of physics to life processes. The ways a primate body plan is structured dictate some of the primary functions and forms of mobility. For example, humans have very robust lower-limb skeletal structures. From really dense femurs, to joints heavily padded with cartilage, our lower limbs are made to take a beating. This feature in our bodies, correlate to how we move about — bipedally.

A new study, published in Biology Letters, studies how orangutans use the sway of branches to propel themselves from tree to tree. They already have longer arms than legs, a useful adaptation to reach from branch to branch. Also their lower limbs are as flexible as our upper ones (if not more)… Isn’t that crazy?

Swaying, as their primary form of movement is way more energetically cost effective than climbing down one tree and up the next and interestingly is seen in only Sumatran orangutans. According to a Nature news report on this study,

“These are the only primates known to live exclusively in the tree canopy, in part because of the Sumatran tiger and other predators that await them on the ground.”

Pretty, interesting tangent between this form of movement and the ecological context the orangutans live in, if you ask me.

The authors of the paper used video footage of Sumatran orangutans in movement to calculate the energy orangutans use in swings, by estimating the weight, mass, and angles observed in the films and plugging them into some classical torque equations.

After all these calculations, another interesting observation was made, about orangutans selecting for ‘stronger vertical branches nearer the tree trunk,’ so that they are less likely to snap under the weight of these big guys.

If you are interested in this publication, it’s published under this title and link, “Orangutans use compliant branches to lower the energetic cost of locomotion.”