My gerbils are chasing each other.....

If the gerbils you have have been together and living in harmony for weeks, or months, and now suddenly they are chasing, fighting, biting...

Separate them immediately....or if more than two, take out the aggressor. You can try putting up a split cage divider and put the aggressor back in and split cage for two weeks and see if they will go back together. However with a larger group, this often doesn't happen.

If the group (two or more) were put together as fairly young pups and they are now 6-8 months old, they could be fighting over dominance (a rank within the group).

If it was a mother and pair of daughters, and the daughters are now 6-8 months old, one or both may be challenging mom. Or, it was mom and daughters, and mom just passed on or was removed for one reason or another... they are now sorting out who's dominant. If it's just two, try split caging them. Often they will decide to get along.

If it is a male group, same thing when the youngest ones come of age or the older one gets old enough.

OR you zarched a sexing in your twosome or multi group, and it's either girls fighting over who will be dominant and who gets to breed with the male.... or it's males fighting over who gets to breed with the female. Watch any apparent mounting behavior and sort it out by the description below. IF for example you have a trio and it ends up to be two of one sex and one of the other...you can either remove the odd sex gerbil and see if the other two settle... or decide to breed and remove one of the duplicate sex animals to leave a breeding pair.

IF you've touched just one animal in the tank, it may be that you've changed their scent/smell enough that the others perceive them as 'intruder' or 'outsider' and attack them. I've heard reports where someone stoked a wood fire, then touched a 3 week old pup... and had the parents shred the pup. In this case you can try to mask the strange smell with vanilla water, mite spray, or some such thing... rub your clean hands with bedding from the tank, rub the animal being bothered with bedding from the tank, then spray everything and everyone in the tank lightly with the spray. IF they persist, then remove the one being picked on. You can try to split cage reintroduce them.... or if in a multi group, perhaps split off ONE of the others, and split cage them with the rejected one to make a new pair.

OR you've got some attempts at breeding going on.

I just put a new one in with one or more I already have....

Any gerbil under 8 weeks old will probably (there are exceptions) accept another young gerbil fairly readily. You do need to take steps to neutralize or make both smell the same... An older male will usually take one or two 5 week old male pups...again, you do something to make sure all smell the same, but the instinct to care for pups in this case, any pups, will get the male to take the young ones.

Any gerbils over 8 weeks old, if you have TWO or more together already, they are 'clanned'. If you try to introduce any other ones, even with split caging, the clanned ones will try to kill the 'stranger' or 'interloper'. IF you have really mellow and/or young gerbils, they might take another one...this time. Later you try it again and they will try to kill the newcomer sooner or later.

It may be that you put some young pups together from different litters, to make a same sex 'dorm' until they get adopted or you pair them up for breeding. The younger they are the more likely this works. As they approach that six to eight month old age, often anytime over four months, it's likely that things will break down and dominance fighting will start...or you took one out to play with and somebody takes offense to their different smell when they come back.

Especially with females, if you take one out to 'breed her then put her back', even though she's in heat and accepts the male...when she comes back she's going to smell different, and that will probably cause fighting. THEN when she delivers, you're likely to lose the pups from another female stealing them, killing them, or the mother being too stressed out and killing the litter. If you want to breed a female from a grouping, expect to take her out and leave her out. Don't pair her up with one of her buddies, as that will cause the same problems. Either pair her up with the male to raise 2-3 litters or don't separate her.

If you take a male out to 'breed him then put him back' you will have the same problems with him smelling different, and probably being rejected by his clan. If you take him out with a friend, expecting to keep that pair separate afterwards, the two males will probably dominance fight over breeding the female, or the two will fight afterwards.

Gerbils are best kept in pairs, trios or larger groupings eventually break down and usually at the worst time (you're asleep, away at work or school, etc). It can take less than a minute for one adult gerbil to kill another.

When finally first introduced after the split cage period, a bit of occasional chasing can happen, especially at the 30 minutes mark, then at 3-5 hours. However up to twelve hours later they can still decide to shred each other.

I thought I had two of one kind but one is mounting the other one!!!!!

This is dominance scent marking if they are the same sex. Look carefully and you will see that the one on top is rubbing the center of the stomach (where the scent gland is) on the back of the other one. Mating, the one on top will be trying to connect rear to rear, not stomach to back. Males or females, same sex pairs, will try to do the scent gland marking sometimes when they are sorting out dominance.

Different sex pair, of course, the female comes into heat every four days, she can do so as early as six weeks, but up to 10 weeks is not uncommon. The act itself only takes a few seconds...but he will be a real pest and continue to do so for hours while she's in heat. If the male was sexually mature and figured it out already, if you have him neutered he will often continue just like he wasn't. The only thing is the female won't get pregnant.

Experienced males have been observed trying to mate with females as small as three weeks old. It doesn't work, the pups are too small and scoot away. By four weeks the pups are big enough to send him packing with their talons... until they come into heat if they're still in with dad at six weeks old.

So. Chill out if you have a same sex pair and double check what parts of the body the two are making contact with.

Grouping gerbils....

Sooner or later a larger group will usually break down. Figure on keeping your gerbils over 8 weeks old in pairs. Where one is pairing off an old animal with younger ones, an old male with two pups or an old female with a pair of younger females... so when the older animal goes the younger pair can continue to live together.

Breeding trios have problems, and eventually break down too. When the group is younger it might work for awhile, but eventually...if two females they will perhaps raise a few litters, delivering about the same time and being supportive...then the dominance issues will surface and one will try to drive the other off...or one will have pups and the other one will try to steal them, and in the stress caused, the mother or the other female will kill the pups (usually around the 4-5 day old mark). If it's two males, males will help raise any pups, they're programmed to. They can fight over who gets to breed the female, and that can cause stress that can cause her to destroy her litter.

Littermates or a few litters, put together when very young (5-6 weeks old) can be kept together in larger groups for a time while waiting for a mate to come out of quarrantine or the like, or before they are paired up to be adopted out. Groups of 5-8 can be established- same sex- but as they get older the more likely they are to have fighting happen. Any time after 4 months it can happen. At best, it will last to 6-8 months when the dominance issues usually come to the surface.

When trying to pair up same sex... an older male usually will take one or two 5 week old male pups. A female, split cage, and usually he'll be more acceptable than she. Try to make sure he's the same size or larger than she is.

When trying to pair up to breed, do a split cage introduction...and if possible, time it to when she's in heat to lift the barrier for the first time and introduce them.

If you want to breed for a limited time, expect to do a 2-3 litter session. Pair the two up, allow them to produce the first litter, and he will rebreed her at delivery. Have him help raise the litter. If possible remove him with the male pups (or if young enough, the whole litter except..) and leave one or two daughters with mom to help her raise the next litter. By six weeks old, make sure dad only has one or two male pups with him. If you don't get the father out in time when she delivers litter #2 she will have one more. You can remove the older daughters and leave one or two daughters from litter #2 to help raise #3, or leave the first daughter(s) in. They will still be young enough not to cause problems with mom in raising #3.

You can remove your pups at 28 days if you absolutely have to, if you've seen them eating solid food and trying or drinking from the waterbottle. Take them out with dad though, as they need to learn various gerbil socialization skills, and he can care for them and teach them what they need to know. Otherwise you can remove them about day 35 and they'll be ready for adopting out in a week. At that age they're weaned and doing well, but keep them one more week before sending them off. If you leave female pups in with dad, they may come into heat at 6 weeks and dad will breed them.

SPLIT CAGE INTRODUCTION

Best done in an aquarium. Construct a divider that goes from corner to corner kittywampus, turning the tank into two triangles. This is the easiest and best way to wedge the divider from persistent efforts to get around it. Put just a waterbottle and possibly a food dish if you use those, one on each side. Once or twice a day, you switch the animals side for side. After two weeks, they're used to each other's smell and so on.

IF they're trying to groom each other, sleep up against the divider across from each other, etc, then those are good signs. Once you lift the divider, you will have to spend 12 hours watching them, with separation container and leather gloves handy. Take the tank with you everywhere, even to the bathroom. It can take them less than a minute to gerbilball and kill one or both. The crucial times are right when you lift the divider, about thirty minutes later, then about 3-5 hours later.

If however one of them is still jumping at the divider, trying to chew their way through just to get at the other one, or trying to bite off toes... after two weeks, give them one to two weeks more without trying to put them together.

Don't clean the tank until after a successful introduction. Don't try to introduce more than one gerbil to one gerbil. More than one gerbil on one side of the split cage will 'clan' and all they want to do is kill the solo one, who usually gets the idea early on and will run, cower, and fight for it's life if cornered. NEVER try to introduce one gerbil to more than one already grouped. The only exceptions are leaving pups with parents, or trying to introduce a pair of young male pups to an adult male.