What does Genesis 8:7 mean?
The previous verse revealed that Noah waited 40 days after the tops of the mountains became visible before opening the window of the ark and sending out a raven. As we'll see in the following verses, the point of sending out a bird was to learn if any dry land was nearby. This practice was used by sailors in ancient times. If the bird they released was not comfortable landing on water, it would fly high and look for land, then head in that direction. If the bird did just that, those aboard would know they were close to land. If the bird came back, it meant it couldn't see suitable land nearby (Genesis 8:9).The raven flies back and forth until the waters dried up. Apparently, this bird never found land, probably returning to the ark regularly until the earth was dry enough to occupy.
Ravens were an unclean bird in God's eyes. Genesis 7:2–3 revealed that God considered some animals and birds clean and others unclean. God had sent seven pairs of all the clean animals and birds on the ark. As an unclean animal, this raven would have been part of a lone pair brought onto the ark. Unless the pair had reproduced already, it would need to survive its search missions in order for its species to survive.