Siamang Duet Song

We visited the zoo on Sunday to capture as many of the animals on film as we could. Meet two of the siamangs at the Riverbanks Zoo. They are the largest species in the gibbon family and are on the endangered species list. The siamangs have a duet song that identifies their territory. The song is made up of loud booms and barks, amplified by resonating sounds across their inflated throat sacs. Make sure the sound is on when viewing this! [Information from the Riverbanks Zoo website.]
Video captured with a Canon 70D and a 100-400mm lens.