When I see birds, and this is a seasonal observation, examples being the Great Egret and Snowy Egret, that have adult characteristics, but are smaller than what I think a female would be, I think they might be juveniles who are not quite adults. The adolescents of the bird world. The Ground Doves you saw could fit my theory, SLB’s theory #1 of bird development. The link below is to Pinellas Birds.
“Take the time to read his fantastic article, linked below” http://www.surfbirds.com/Features/coxpeeps1006/coxpeeps1006.html
I am copying it and know I will have occasion to refer to it. -SLB