Ornery Western Painted

Question
Hi Mark,
I have a 500 gallon pond in my backyard with one male and one female western painted and one male eastern painted and one female midland painted.  I have had them for several years and they all get along wonderfully...except the male western.  He seems to delight in biting the other turtles behind the head on the back of the neck.  It is not food related and it seems to be constant.  He has been doing this since we first put him in the pond.  I would like to figure out if this is a mating, dominance or personality related issue.  Can you shed any light on this?  Thanks for your help.

Answer
Quick answer- sounds like he is a bully. This happens sometimes, and I have never seen an absolute solution other than separation.

Some argue that the size. shape, configuration, etc. of the habitat is an issue, and it might be. Others figure that it is the personal chemistry between certain animals.

The 'born bully' theory points out that some of these animals act like this pretty much no matter what the other circumstances. They seem to appear in any species, although some species are more likely to turn bully than others. Painted are not a common bully species.

Now- there is also another theory that may come into play here- the 'mixed signals' theory. Here, the idea is that behaviors trigger responses. In a subspecies, the 'bully' does not respond to the triggers in the intended way because of what is essentially a miscommunication.