In Genesis 6:7, it is written,
7 So the LORD said, “I will destroy man whom I have created from the face of the earth, both man and beast, creeping thing and birds of the air, for I am sorry that I have made them.” NKJV, ©1982
The reason for God’s destruction of humankind is explicitly stated in the previous two verses:
5 Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually. 6 And the LORD was sorry that He had made man on the earth, and He was grieved in His heart. NKJV, ©1982
However, what reason does the Bible give for God destroying the rest of animal creation, such as the creeping things, birds of the air, etc.?
This related question seems focused on the reconciliation of an apparent contradiction but does not necessarily ask for the basis of the extermination of the animals in the flood.