Smith (1987) lists the following key differences which should be considered in combination. The first four are considered most dependable and consistent. Note that the extent of white outline around the black neck 'slash' mark is not considered a reliable field mark, contrary to the information given in the National Geographic Society Field Guide (1987), although on average, the Eurasian Collared-Dove shows more white there.
 

	Eurasian Collared-Dove	Ringed Turtle-Dove
Call:	Unrolled "kuk-koooOO-kook", often in series	Rolled "kooeek-krrrooooo(aw)", with pauses
Cry note:	Harsh screaming mew	Soft jeering laugh
Vent and undertail coverts:	Gray, no contrast with other underparts	Whitish, often contrasting with belly
Outer tail feathers:	Outer web mostly dark	Outer web mostly white
Size:	Much larger than Mourning Dove	Usually somewhat larger than Mourning Dove
Body Color:	Pale sandy brown, with buffy gray neck	Variable, often creamier or pinker, lacking gray tone
Wings:	Primaries darker than rest of wing	Primaries often not much darker than rest of wing
Tail shape:	Long, rounded or square	Variable, often more pointed
Tail underside:	Dark basal underside reaches tip of undertail coverts	Dark basal underside rarely approaches tip of undertail coverts
Behavior:	Usually shy, not allowing close approach	Meek, usually approachable

 
Birders have an excellent chance to witness and to document the spread of a species. All collared doves should be carefully examined.

According to member B.J.Norris, these birds have really spread through Florida.  She writes:

"I saw my first Eurasian Collared-Dove in February of 1994, and had a terrible time identifying it. Now in Florida Eurasian Collared-Doves are absolutely trash birds, they're everywhere, everywhere. So in 8 winters I went from my first spotting to where we are watching for them in Virginia. The mottling at the collar is to me an extremely distinctive feature, even visible from a telephone wire."