Prothonotary Warblers should be known, in my opinion, as the field mark appropriate, easier to remember & pronounce, Golden Swamp Warbler.
This is another example of obscure 18th century conceitful naming. Prothonotaries are papal clerks that wear yellow robes. Yellow being the only common characteristic & certainly not a connection known by common folks, especially those that share the swamp habitat.
Golden Swamp Warblers have two characteristics that are not serving them well. Their preferred breeding habitat is forested bottomlands & swamps. They are only one of two North American wintering warbler species that nest in dead tree cavities. Their habitat & nesting preferences are both rapidly disappearing.
Golden Swamp Warbler populations have declined .7%\year, 31% total, since the mid-1960s. They are a species of high conservation concern with a Continental Concern Score of 14 out of 20 & are on the Partners in Flight Yellow Watch List “D”.
The little bit of good news is they will use nest boxes. For example, launched in 2019 South Carolina Wildlife Federation Project Prothonotary, led by Jay Keck, has installed 500+ nest boxes. The early success rate of over 50% of the boxes hosting nesting pairs is very promising.