Why does the rat have wings in "Cloudy with a Chance of Meatballs"?

Question

I was watching "Cloudy with a Chance of Meatballs", then I saw one scene which contains a rat with wings.

Is there any reason for this?

Answer 1

The Ratbird was one of Flint Lockwood's early experiments

This is shown at the beginning of the movie as they are showing "highlights" of his inventions.

They escape from the cage and live feral on the island. No reason is given as to why Flint created these hybrids.

Answer 2

In many cultures, urban pigeons are considered "rats with wings". I guess in CWACOM, this could be a wink to such cultural concept by explicitly creating a dirty rat with wings that behaves like an urban pigeon.