What is going on with black buttocks and shit

Black buttocks are usually caused by birds.It mainly eats insects. It can eat larvae, naphic moth larvae, maternal larvae, locusts, golden turtles, beetles, pedestrian insects and other winged insects.And larvae.Most of this bird predation insect is in spring and summer, and insects can not be found in autumn and winter. They can only eat fruits such as camphor seeds and banyan fruits, as well as the seeds of some weeds.