Great-tailed Grackle

Update:
It was pointed out to me by Joel Geier that these were more likely shorter tailed Great-tailed Grackles rather than Common Grackles as Las Vegas is a bit out of range for a Common Grackle. He was kind enough to forward the issue to Martin Meyers of the Nevada Bird Records Committee. Martin verified that these are indeed Great-tailed Grackles. As he explained "The males in the photos show typical Great-tailed coloration, without the clean delineation between head color and body color (at hindneck and mid-breast) shown by all races of Common Grackle. Also, as you (Joel) pointed out, the bills on these birds are larger and more curved than typical of Common Grackle."
Thanks to Joel and Martin for setting me straight and teaching me something!

Original Post:
In the grass surrounding the parking lot of the hotel I stayed at in Las Vegas, there were many Grackles foraging for food. The interesting thing about them is that many, like the bird in the middle image, were missing most of their tails.
The top image above, shows a male with what I assume is fairly standard plumage. It was this bird, with its full tail, that led me to the conclusion that these were Common Grackles and not Great-tailed. The tail just doesn't seem long enough to be a Great-tailed.
After looking at the pictures I had taken and doing some research on the web, I'm fairly sure these birds are molting. As you can see in the second image from the top, this Grackle shows signs of molting on both the back of its head and on its wing. See Greg Gillson's site for a discussion on molting Grackles.

There were also many juvenile Common Grackles as can be seen in the bottom two images. Note that its bill appears to be crossed at the tip. I noticed this on several of the birds, though I haven't found any documentation about this on the web.