Rat behaviors.

Question

Cricket Playing   A little background: Almost a year ago to the day, my boyfriend and I adopted two six-month old female albino rats from our local Animal Rescue League. The girls had been owned by a school teacher and were the pet rats of her class, until she decided to give them over to the ARL for adoption. As such, their only real socialization was young children and it led to quite a bit of work for the boyfriend and I to trust train them.

Over the past year, we have really come to know our girls and their very distinct personalities. But a few things just seem a little strange to us. Now bad, per se, but just odd to see in a pet's behavior.

Firstly, Skitrik, the rat who bonded to my boyfriend, is -extremely- skittish. She's not unfriendly and loves to play, but even the slightest noise or movement will have her leaping across the cage in surprise. She always seems to be tense, even when in the safety of her cage, and her movements reflect that. Beyond that, she is perfectly healthy and seems quite happy, both with her home and her Humans.

Then there's Cricket, the rat who bonded to me. She's very calm, in stark contrast to Skitrik, and loves to just lay about wherever she can be in view of us. However, she seems to have developed a nervous tick - she has chewed the fur off of her left front leg, just above her paw. She has been doing this for months and there is no damage to the skin and no sign of any irritation, just the missing fur. In addition, she has a few habits that, in a Human, would be considered very OCD-like behaviors. Certain items in the cage have to be in their proper place and if they get moved, either by her sister or during cage cleaning, she will immediately move them back. She also keeps a layer of bedding on the top of their food in their dish, likely an instinct to bury it, and will even try to fix this while Skitrik is eating!

I don't think that these are really behaviors to be worried about, but they were just so unusual that I thought I would share them and ask if you have heard of things like this in rats? We love our ratty babies and all of their quirks.

Answer
Yes, like humans, each rat comes with its very own unique personality.  The skittish-ness of Skitrik may in part be the fact that she wasn't handled from birth and handled improperly after that in the classroom environment.  Your Cricket has obviously adjusted quickly to her life with you, but Skitrik not so.  I have a 2 month old rat right now who I adopted from a good breeder.  This baby has been handled from birth by the breeder, yet she is quite skittish also.  I chalk it up to just her personality, as her sister is not so at all.

Regarding Cricket's OCD-like behaviors: although rats love and need to be stimulated by new things to play with to keep them stimulated, rats, like humans, tend to be creatures of habit.  Covering a food bowl with bedding or other things from their cage is a very common behavior in rats.  It is also common for rats to like their things a certain way.  My former rats used to build a mountain out of their bedding always in the same place in their cage and every time I knocked it down, it would be rebuilt within a short time.  All rats like to groom themselves and their cagemates but some rats over-groom.  This is referred to as "barbering".  Some such rats barber their cagemates to the point of baldness.  Other excessive groomers do it to themselves.  I also once had a girl who shaved off all the fur on both back legs.  Her barbering behavior lasted a few months, but eventually stopped altogether.  Sometimes barbering is due to stress.  

All in all, you have two girls with unique characteristics that that you likely won't be able to change.  None of the behaviors you described are rare.  I have heard of many other even more odd behaviors by rats that are still considered normal.  Enjoy your little beauties...I guarantee that some of these quirks will often be remembered fondly in the future.