Unusual Dove? Arapahoe County

[Cheri Phillips]

I happened upon this dove yesterday and wanted to share it with others. I have a couple ideas what it is but wanted to see what other more experienced birders thought it might be. Is it a Leucistic Eurasian Collared-Dove or is this a Ringed-Turtle-Dove? If so is it an escapee or will it be like the Eurasian Collared-Dove spreading throughout the U.S. The 2 doves pictured were exhibiting what I thought might be nesting behavior.

http://imgur.com/LaxZMlZ

Cheri Phillips
Centennial, CO

[Paul Hurtado]

These pale forms of the Eurasian Collared-Dove (EUCD) occur in low numbers throughout their range in North America -- a nice little reminder of their semi-domesticated origins.

But how can we know for sure whether this is a EUCD (Streptopelia decaoto) or a Ringed Turtle Dove (S. risoria; aka African Collared-Dove aka Barbary Dove aka lots of names)? 

The best field mark I know of is one that isn't always easy to see, but happens to be captured pretty well in this photo: black "tail spikes".

On EUCDs, the dark at the base of the outer tail feather extends down the outer feather vane into the whitish color that forms the rest of the underside of the feather, giving the tail these black "spikes" that creep out towards the tail tip on either side of the tail. Other Streptopelia doves lack this, as far as I know, S. risoria in particular.  Other differences include less black visible on the underside of the tail in S. risoria, and white (not gray) undertail coverts.

Here's a link showing one comparison (I'm sure other such comparisons can be found online):
http://www.internationaldovesociety.com/RNColorPics/RNECDCompare.htm

I should mention that these two species can also hybridize, so it's worth documenting birds that look intermediate in their tail feather coloration.

Good birding,

-Paul Hurtado