The Screaming Cowbird parasitizes almost exclusively the Greyish Baywing. A characteristic of this parasitism is the similarity of the plumage in the chicks of these two species till the time the screaming cowbird begins to change into adult plumage. Black spots begin to cover the Screaming Cowbird's body till it becomes black. In these photos we can see practically the beginning of this process.

The screaming cowbird parasitizes almost exclusively the Greyish Baywing. A characteristic of this parasitism is the similarity of the plumage in the chicks of these two species till the time the screaming cowbird begins to change into adult plumage. Black spots begin to cover the screaming cowbird's body till it becomes black. In these photos we can see practically the beginning of this process. .

In latin rufoaxillaris refers to the rufous axilla. It is only a couple of feathers

A day with too many screaming cowbirds. These were the first four of the walk

Two photos to see the differences between these two cowbirds: Screaming Cowbird and Shiny Cowbird.They belong to the Family Icteridae and both are parasitic 
Differences: The violaceous blue of the Shiny Cowbird and the glossy black of the Screaming Cowbird. Bill length. Shorter in the Screaming Cowbird (in Spanish it takes its name after this difference) and longer in the Shiny Cowbird. The chestnut iris in the Screaming Cowbird and the dark iris in the Shiny Cowbird.