The langurs, the big gray-whiskered monkeys of the Himalayas, were, naturally, the first, for they are alive with curiosity; and when they had upset the beggingbowl, and rolled it round the floor, and tried their teeth on the brass-handled crutch, and made faces at the antelope skin, they decided that the human being who sat so still was harmless. At evening, they would leap down from the pines, and beg with their hands for things to eat, and then swing off in graceful curves.
This is from "The Miracle of Puram Bhagat " by Rudyard Kipling.
I don't understand the meaning of---
and then swing off in graceful curves.
I am glad if someone would kindly teach me.