"After forty days Noah opened the window he had made in the ark and sent out a raven, and it kept flying back and forth until the water had dried up from the earth." NIV translation
Another forty days after the ark came to rest and then Noah sent out a raven to check out the land. A raven was an unclean bird because it ate dead flesh and so it kept flying back and forth in search of food. It would do this until it could find dead animals to feed on and, when it did, it did not come back to the ark. This is also a picture of those who "come to Jesus" without really coming to Jesus. There are those who have heard a watered down gospel and do not truly accept Jesus as their Lord and Savior. These people are like the unclean raven who have simply come to God to get what they want or need. When they can get what they need to satisfy their physical body elsewhere, they fly away from the Lord.
"Then he sent out a dove to see if the water had receded from the surface of the ground. But the dove could find no place to set its feet because there was water over all the surface of the earth; so it returned to Noah in the ark. He reached out his hand and took the dove and brought it back to himself in the ark." NIV translation
The second bird that Noah sent out was a dove and it kept returning to the ark because it did not eat dead flesh.
This is a picture of our walk as Christians. We may make mistakes but, when we do, Jesus is waiting there to welcome us back into God's will for our lives.
"He waited seven more days and again sent out the dove from the ark. When the dove returned to him in the evening, there in its beak was a freshly plucked olive leaf! Then Noah knew that the water had receded from the earth." NIV translation
We are reminded that throughout the Bible, the number seven is associated with completeness. Therefore, Noah waited seven days to send the dove back out to see if the water had gone down. This time it returned with an olive leaf and so Noah knew that the water had went down.
"He waited seven more days and sent the dove out again, but this time it did not return to him." NIV translation
After seven more days, the dove was sent out but this time it found a place to land and food.