Science Snippet: Caloric Consumption of Sloths and Hummingbirds

Three-toed sloths of Costa Rico are the poster-children for the word “sloth.” In fact, these are the slowest mammals on earth. They spend most of their lives in a few trees and pass their time resting, eating or sleeping, and when they move, it’s at a snail’s pace. Every week or so they slowly make their way to the ground to poop, then leisurely go back up the tree to rest. Maybe even sleep. The average human male consumes about 2,500 calories a day, while a female needs about 2,000 calories. The sloth, on the other hand, consumes 680 calories/day. Compare this with the average hummingbird, with a heart rate of 500 beats per minute and consuming about 50 percent of its body weight a day just to maintain its one-eighth of an ounce body weight. These little birds require 6,600 to 12,000 calories/day. (Scientific American, 2016, November issue; lib.niu.edu, Aug. 2000, article by Eilertsen and Day)