Locomotion of the Red-Shanked Douc Langur (Pygathrix Nemaeus) in the Son Tra Nature Reserve, Vietnam
Abstract
This study aims to compile data on the locomotor behavior of the red-shanked douc
langur (Pygathrix nemaeus). This dissertation focused on establishing the historical
context for primate locomotion studies and provides a brief introduction to the odd-nosed
monkeys, of which Pygathrix is a member. Furthermore, this dissertation contributes
locomotor and some anatomical data relating to the arm-swinging capabilities of the redshanked
douc langur.
Landmark data was used to identify elements of scapular shape to infer locomotor
behaviors. I used shape data on the scapula of the douc langurs to identify if the three
species of Pygathrix share a similar scapula shape. There was no statistically significant
difference in scapular shape between the three species, thereby lending some support that
all are likely moving in similar ways. I also used landmark data to compare Pygathrix (all
three species) to quadrupeds and brachiators and found Pygathrix to be significantly
different from both. Landmark data was also used to calculate the straight-line distance
between the distal most portion of the acromion process and the center most point of the
glenoid fossa to see if this distance could predict locomotor behaviors. For species that
routinely use their arms for locomotor purposes (i.e. brachiators, quadrupeds, and armswingers)
there was a significant difference in distance between the groups. When
incorporating bipedal individuals, there was less of a significant effect.
In addition I looked at behavior data from the Son Tra Nature Reserve in Da Nang
City, Vietnam to identify elements of wild locomotion. I looked at body size
characteristics to determine if heavier individuals were arm-swinging more or less than
lighter individuals. This study showed that in fact, the lightest individuals (juveniles) used
arm-swinging the most, followed by sub-adults, adult females, adult females carrying
babies, and then adult males. Finally, I identified environmental variables and how those
variables correlate with the red shanked douc’s locomotion. The results of this study
indicated that doucs prefer to arm-swing in old-growth forest, in the main canopy, and on
horizontal and medium sized substrates.
Citation
Bailey, Kathryn Elizabeth (2018). Locomotion of the Red-Shanked Douc Langur (Pygathrix Nemaeus) in the Son Tra Nature Reserve, Vietnam. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174610.