How cowbird chicks avoid imprinting on their hosts

Cowbirds are well known to lay their eggs in the nests of other birds, leaving the young to be raised by other species.
So how do Cowbird chicks avoid imprinting on their host families of Gnatcatchers, Warblers or Blackbirds yet still learn how to be a Cowbird?

A study by the University of Illinois was launched to answer this question. Researchers tracked juvenile cowbirds that were being raised by Prothonotary warblers. They’ve discovered that, at around 30 days old, cowbird fledglings started to leave the warblers’ territory at dusk to roost alone.
They would then return the following morning to be fed by their foster parents. For reasons that aren’t yet clear, these nocturnal departures seem to prevent the young cowbirds from imprinting on their host parents.

Interesting info for sure! But how exactly do Cowbirds learn how to be Cowbirds and not pick up on the habits of their host families?

I’ll post more on that question tomorrow…
Photo by @sally_siko of Birdwatching NC
Canon 5DS