introducing a new turtle

Question
We have a 3 toed box turtle that we have had for over a year named Turdy.  We think he is a male because of his reddish brown eyes and bright orange spots.  My husband rescued another 3 toed box turtle and we thought Turdy would like the chance to have a turtle friend.  Turdy already plays with our pugs, cat and rabbit, so we know he is friendly.  But when we introduced the new turtle into the turtle pen, Turdy became rather aggressive and chased after the new turtle.  I separated them many times and after an hour, they seemed to settle down.  But Turdy would still run over to the other turtle every now and then and snap at the others turtle.  The other turtle which is almost twice the size of Turdy,closes it's shell and just lets Turdy bight at it's shell.  Then Turdy will wander off and the new turtle goes about it's business.  Now the new turtle crawled into Turdys little house and layed down in Turdy's bed.  Turdy looks mad and is just sitting there watching and smelling the new turtle.  Is this behavior normal?  Do we need to separate them?  I don't want either one to get hurt.

Answer
Hi Stephanie,

Turtles and tortoises aren't as sophisticated in their reactions to other animals and situations as dogs and cats can be.  They react to things based on instinct and to some extent experience.  So if you introduce a new turtle to an established territory, it's not unusual for there to be some apparent aggression going on, such as biting, chasing, ramming, etc.  Usually they'll settle down eventually and get along fine, so just monitor the behavior.  If you can move some things around in the pen, such as rocks, logs, hides, etc., that can help, too.  But Turdy isn't "mad" or upset, or sulking in the way that we think of those emotions.  He's just reacting to a change in his environment/territory.  

If the new turtle is a female, you may see some mating behavior going on, and that may become a problem because males can be very aggressive and persistent if there's just one female.  If that happens, you may need to either divide the pen or add more females so there's less stress.

Here's a website that will give you more information on care and different species:  www.aboxturtle.com.