Slow Sloths!

One of the most viewed animal video on youtube is a video titled “Strange animal cross the road”. With over 10 million views, it featured an exceptionally slow moving animal trying to cross a busy road in Manuel Antonio, Costa Rica. Other than this video, many other videos of this particular animal are very popular on the Internet as well.

Strange Animal Cross the Road

The animal captured in the youtube video is the Bradypus variegatus, commonly known as the brown throated three-toed sloth. Three-toed sloths tend to stay in the same tree for long periods of time, from day to night. Even when they move, there were very low rates of movement and they moved a mere 0.14 kilometers per day (Sunquist and Montgomery, 1973). Also, they are known to have very limited sense of balance (Britton, 1941). In particular, progression is even slower when the animal is on all fours on the ground (Britton, 1941), which explained the exceptionally slow motion of the three-toed sloth in the video.

Brown-throated Three-toed Sloth




(Brian Henderson, 2011)




However, it is also interesting to note that in spite of the slow moving nature of the Bradypus variegatus, agonistic behavior is also found in a study. It describes a field observation of an agonistic encounter between two males. Observations by Greene (1989:369) showed that both male sloths move at a rapid speed, with one climbing down the tree at “three times ‘typical’ sloth speed’ and the other “rapidly descended to the basal crotch of the tree”.  The study suggests that such behavior might be attributed to the defense of female, food or other resources. Brattstrom (1989:348) also observed a three-toed sloth “move rapidly in response to a rainstorm”. And so, sloths seem to be capable of moving faster than commonly thought.


Literature Cited

Brattstrom, B. H., 1966. Sloth behavior. Journal of Mammalogy, 47(2):348.


Britton, S.W., 1941. Form and Function in the Sloth. The Quarterly Review of Biology, 16(1):           13-34.


Greene, H. W., 1989. Agonistic Behavior by Three-toed Sloths, Bradypus  variegatus. Biotropica, 21(4): 369-372.


Sunquist, M.E. & Montgomery, G.G., 1973. Activity Patterns and Rates of Movement of Two-          Toed and Three-Toed Sloths (Choloepus hoffmanni and Bradypus infuscatus).  Journal of         Mammalogy , 54(4): 946-954.



“Brown-throated Three-toed Sloth” by Brian Henderson. Flickr, 1 Nov 2011. URL: (accessed on 2 April 2013)

“Strange animal cross the road” by Ahmed Refaat. URL: (accessed on 1 April 2013)