Tail-less Grackles?

I moved to Houston, Texas about three years ago from Southern Nevada, and I have really been enjoying the masses of starlings and grackles that live here. I had never seen so many birds at once before! I've always kept my eye on the little noisemakers throughout the seasons and have identified the different types that hang out in these motley crews (starlings, common grackles, boat-tailed grackles and great-tailed grackles).

However, recently, I have noticed something/someone different - I noticed early this spring (however, I still spot them now) that there were grackles without tails at all. I have been told that birds cannot lose their entire tail when molting. They are the average size of an adult, which would rule out fledgling. Some have suggested that what I have seen are not grackles at all perhaps just cowbirds (are they not the same, by the way?) I’m positive that they are grackles - they have the same body types/color/eyes/call just no tails. They almost look like a cross between a starling and a grackle. Though I’m not suggesting that that is what it is at all! Unfortunately, every time I see this type of bird I do not have my camera with me. I would be more than happy to sit outside and wait for one to make a cameo if you need a picture! Otherwise any information on this phenomenon would be greatly appreciated. Thank you for your time. Sarah C. Houston, TX