In the biblical Noah’s Ark story, Noah first sent out a raven before sending a dove. Genesis 8:7 says he released the raven after the waters began to recede.
The raven is described as flying back and forth until the waters dried from the earth. Noah then sent a dove to find out whether the water had receded from the ground. The sequence makes the raven the first bird explicitly released in this part of the narrative.
The dove’s later flights receive more detail. It first returns because it finds no resting place, then returns with a freshly plucked olive leaf, and finally does not return when the land is dry enough. These events are distinct from the raven’s earlier release.
Because the dove is more famous in popular retellings, people sometimes remember it as Noah’s first bird. Genesis, however, names the raven first. The question asks about order, so “a raven” is the specific answer.