Leviticus 1:14
And if the burnt sacrifice for his offering to the LORD be of fowls, then he shall bring his offering of turtledoves, or of young pigeons. And if the burnt sacrifice for his offering to the LORD be of fowls, then he shall bring his offering of turtledoves, or of young pigeons.
The burnt sacrifice to the Lord could be made from birds, namely turtledoves or young pigeons. This provision of fowls was a less costly way by which a poor person could still bring a burnt sacrifice. Though its cost was smaller, the humble offering demanded the same care and exactness in preparation as a costlier offering. When it is all the poor are able to give, such a humble gift is accepted, as shown by the fowl offering presented by the poor parents of Jesus.