Mourning Dove color variation

I was just curious if any other people have seen dark variations of Mourning Doves where they live. I photographed this chocolate brown mourning dove at Sweetwater Wetlands in Tucson(AZ). Is this color variation common or does this have something to do with breeding?
I have been back twice but have not found this bird since.
Thanks for any feedback.
Jim

I cannot answer your question except to say that at my feeders in North Georgia, I have seen color variations in the Doves that visit. Some are dark as yours while some are a beautiful gray color. I have even noticed that there are differences in the gray shades, some very light while some darker. Ray Dove

I have seen similarly colored doves in the Caribean which I think were Eared Doves. But they have a purplish patch on the side of their necks, an area that's hard to see on this photo.

Correction: Zenaida Doves have a purplish patch; in Eared Doves it's more golden.

This looks more like a dark stain on the feathers than it does a color variation in the feathers. I've seen this before at a wastewater facility near Chandler, AZ, where there's lots of "organic material" of a similar shade in the open "water" areas.

For those suggesting other species of doves please note that it takes more than a similar color to be a different species - this is clearly a Mourning Dove.

I'm thinking that Ray is probably the expert on this subject (sorry Richard) but the guys last name is DOVE. I mean, come on. . . the discussion should begin and end with what he says!

All joking aside, Richard, how would a mourning dove come about this staining? Bird baths?

I have always thought this was a Mourning Dove and was inquiring if Mourning Doves had any color variations like a lot of other bird species have. I understand what Rich is saying but what made it a little confusing is that we got a really good look at this dove through binoculars and it did not appear to have any organic matter or mud or dirt hanging off its feathers or body. A lady from NY thought this might be a Zenaida but in looking at her NG Bird Field Guide of North America that dove is over in the Florida Keys.
Being new to the birding world I had just never heard of a bird's plumage being stained from something it landed on or landed in. The mourning dove is not exactly what I would call a water bird, so for it to land into something that would stain it from head to toe is kind of interesting to me. Thanks to Rich and all for this feedback.

Jim (and Luke):

All birds will bathe when they get a chance - all they need is shallow water like in a backyard birdbath. Our Mourning Doves use ours daily, along with the Inca Doves and mockingbirds and Lesser Goldfinches. At sewage treatment facilities they will do the same thing along the shallow edges of the sewage lagoons where they can easily pick up a brown stain.

Here's an example House Finch that's been bathing in a small water feature at Boyce Thompson Arboretum - note how the entire belly is wet.

And here's a Rock Pigeon taking a bath on a hot day in Phoenix in a shallow park pond (a film scan from 2002).