Probably a little of both. I've read that the does will run off the young bucks, but some have probably been orphaned too.

I just watched a little button buck today. At first I thought (hoped) it was a doe being chased by a buck. After no bucks showed up, I guessed it was a button. Then I was sure after it found a little twig of a sapling and started rubbing it with it's forhead.

You are correct in that young buck tend to have shorter snouts than does, also.

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Live: Oregon, IL
Hunt: Knox County, IL