The widely accepted estimate is that there are about 9,000 different species [of birds] in the world . . . Although I have had the privilege of traveling in many countries and habitats, I have seen only about 2,500 species.
Only one person has seen them all, and that of course is God himself, their creator “… So God created…every winged bird according to its kind. And God saw that it was good” (Genesis 1:20-21). In consequence, he is able to claim: “I know all the birds of the air, and the creatures of the field are mine” (Psalm 50:11, literally). More than that, since Jesus said that not a single Sparrow falls to the ground without the knowledge of God (Matthew 10:29), he must know not only every species of bird, but every individual member of each species as well. And that would mean many thousands and millions.
– John Stott, The Birds Our Teachers, pp. 8-9, quoted in Rejoice! Advent in All the Scriptures (affiliate link), by Chris Wright with John Stott