"Are they trying to make birds extinct or what?"
Monkeys steal bird eggs and prey on small birds, but preying on baby birds in nests on such a large scale definitely had a cause.
Instead of eating the tender, juicy buds and blossoms of spring, they chose to eat bird eggs—most likely, there was some animosity between the two.
The four of them hid under the bushes and used binoculars to observe the group of Gray Leaf Monkeys that were slashing birds and removing eggs.
Due to the different color of the Gray Leaf Monkey's offspring, it was clear to differentiate, and the mothers carrying young did not participate in this killing spree.
A few male monkeys took the eggs they found and ran to the female monkeys to show their affection. Most of the female monkeys accepted the eggs fed to them.
