What are some 4 letter birds that begin with the letter S?

Sure are, try

Swan, Seagull, Sparrow, Stork, Sand piper, Scarlet Tanager, Screamer, Snow goose, Snowy Owl, Spoonbill, Starling, Swallow

Not to mention many more that start with adjectives such as, Small, Spotted, Speckled, etc.,