I would like to add a different perspective to the conversation.  I am not a 
lister.

But what I do is document the fauna of Hart-Miller Island.  From a 
scientific standpoint, it is significant to make subspecies differentiations 
of species when possible.  Individual subspecies are populations that have 
specific geographical distributions.  By documenting the subspecific 
occurrences, we obtain a more detailed picture of what population visits the 
island and when.  We can possibly detect temporal differences if both 
subspecies occur.  If one subspecies regularly occurs and another only 
rarely occurs as a vagrant, the pattern of vagrancy can be tracked.  If only 
one subspecies occurs, it is significant which subspecies it is.

For Hart-Miller, the following distinctions have been made:
Green-winged Teal ("carolinensis" only)
Willet (both "Eastern" and "Western" regularly occur)
Whimbrel ("North American" only)
Dunlin ("hudsonia" regularly occurs; other subspecies - a few summer 
occurrences)
Short-billed Dowitchers (both "griseus" and "hendersoni" regularly occur)
Lesser Black-backed Gull ("graellsii" regularly occurs; "intermedius" twice)
Northern Flicker ("Yellow-shafted" only)
Cave Swallow ("Southwestern" only)
Yellow-rumped Warbler ("Myrtle" only)
Palm Warbler (both "Yellow" and "Western" regularly occur)
Eastern Towhee ("Rufous-sided" only)
Savannah Sparrow  (unidentified subspecies regularly occur; "Ipswich" is a 
vagrant)
Swamp Sparrow ("Coastal Plain" breeds; inland subspecies regularly migrate 
through)
Dark-eyed Junco ("Slate-colored" only)
Common Grackle ("Purple" only)

Gene Scarpulla
Millers Island, Maryland