Comment by JoeAltmaier

Birds will arrive the day before fruit is ripe, and the whole flock will strip the berries, trying each one and dropping the green ones on the ground looking for a ripe one. They can strip a tree in minutes. Why? If they waited a day, the whole flock could have ripe fruit. But its a flock, and any bird that waits just loses out to the ones that don't wait. Tragedy of the commons, played out in evolution.