According to it's kind.

"And God said "Let the water teem with living creatures ...and every winged bird according to its kind.  And God  saw that it was good."  Genesis 1 v 20 and v21

This swan on the lake was a welcome surprise to me as I passed through the park.  The only one of it's kind, visible to us at the time, floating along and seeking food like the other birds around it.  The elegance  and beauty of this bird was unparalleled to the other feathered creatures in the lake.  I wondered how far it was from other birds of its kind.