Smithsonian Howler Monkey Census Results Are In

There are 1,200 howler monkeys on Panama’s Barro Colorado Island according to a recent Smithsonian Tropical Research Institute census.

By triangulating monkey sounds from 35 predetermined listening stations, research volunteers estimated that there are 60 to 70 fairly closed social groups of howler monkeys on the island with an average of 17 to 18 monkeys per group.  According to the fifth Howler Monkey Census, the numbers are not much different than 33 years ago.

“It doesn’t look like howlers on Barro Colorado have suffered from any devastating diseases or other catastrophic problems for the last three decades,” said Katie Milton. “Groups are larger at some times of year and smaller at others, which seems to reflect births and the specific causes of death that affect different ages of monkeys at different times of the year.”

Milton is a professor in the department of Environmental Science, Policy & Management at the University of California, Berkeley and performed the first census in 1977.

Click here to access howler monkey sounds and an interview with Katie Milton.

Baby Howler Monkey with bot fly lesion on neck / STRI PRESS PHOTO

Information provided by the Smithsonian Tropical Research Institute.