I believe the ""warblers" of Europe, like Willow Warbler, are not really closely related to the New World Wood Warblers. I could be wrong, but I think the name "warbler" implies a closer relationship than really exists. Thanks for following. I found an interesting article discussing this issue: https://www.allaboutbirds.org/whos-got-the-best-warblers-and-why-europe-vs-america-edition/