box turtle egg

Question
We bought a male Russian Tortoise in December of last year and kept him in an indoor aquarium. Around two months ago we almost ran over an Eastern Box Turtle in the highway so we brought her home and built an outdoor pen complete with a pond and took a chance and put them together. They are both thriving and tonight we found an egg underneath one of the arc shaped things for them to get under. Is it possible they mated across species or is it more probable she had already mated before we brought her home? Do you think there is a chance the egg will survive? We did not touch or move it. Also, should the male tortoise be moved back into his aquarium while the egg is hatching? Thank you so much for your help!!!

Answer
Hi Dianne,

There's quite a few issues here that need to be addressed.  So, first, the egg.  No, it's unlikely they would mate (successfully--the Russian might try as they're pretty frisky boys), and if they did, any eggs produced would be infertile.  Turtles can storm sperm and lay without a male, too.  Box turtles dig nests, and often if the egg is laid on the surface it's not fertile.  At this point, being out in the open the egg probably isn't viable even if it was fertile.  I'll link a box turtle page for you below that also has information on breeding and incubating eggs, in case you're interested in the future.

OK, now for the other issues you mentioned.  You should separate your box turtle and tortoise, for several reasons.  One is that it's never a good idea to mix species, and in particular mixing wild caught specimens (as both your box turtle and Russian tortoise are) could turn out to be deadly in time.  Different species carry different pathogens to which they're immune, but other species may not be.  Recently wild caught Russian tortoises are sometimes infected with a herpes virus, not harmful to people, but can be fatal to other tortoises/turtles.  This virus is something that may not show up for years, but has been known to wipe out entire collections.  In turn, your box turtle could be carrying something dangerous to the Russian.  So for that reason alone, I highly recommend separating them ASAP.  The other reasons are 1) they have completely different care requirements (boxies are omnivores and need a moist environment, while Russians are strictly herbivores and too much wet can lead to respiratory infection; 2) the Russian is very likely to drown in the pond at some point.

The good news is that the boxie can live outdoors all year round, and that's great.  In the fall, provide an area of soft dirt with a pile of leaf litter, straw, etc. for her to dig into for hibernation.  The Russian should do fine outside from spring to fall, but will need to come inside for the winter (there are a few states where one could be outside all year round, but I don't know your location).  The bad news is, you need to provide a better enclosure than a tank.  Tanks are usually much too small, and because of the glass don't provide a good temperature gradient.  I'll link a website for you below, and if you look under "care sheet" you'll see the information you need to set him up properly using a 50 gallon Rubbermaid bin.  Ideally, you can get him into something bigger than that (tortoises do better with plenty of room), but if necessary the bin will do for winter.  

This was probably more information than you were looking for, but if posters mention things that I feel should be addressed then I try to give the information needed to make changes.  I'll link a couple of websites below.  Both have information on breeding/incubating, so you can read that over, as well as information on enclosures and diet.  Good luck!

http://russiantortoise.org/
http://aboxturtle.com/