Catherine kindly provided two pictures of her hamsters, helpfully sleeping on their backs with all their "bits" on display, to help us to determine the sex of our baby hamsters.

    

These pics are of Sean and Sayer, both boys.

I think from Sean's pic (on the left) the scent gland makes it easy to determine that he is a boy, in Sayer on the other hand I would not have been so sure.
Could somebody just clarify here the main ways to tell male and female hamsters apart please?

Hamsters generally reach sexual maturity from 4 weeks old, meaning the male and female hamsters are able to mate and have babies. Therefore, it is important to start sexing baby hamsters and separate them by gender from 4 weeks onwards.On the male, there is a significant distance between his male sexual organ and his anus. On the female, the distance between her sexual opening and anus is much shorter.
The male usually has a protruding rear due to the location of the testicles.Also male Dwarves have a scent gland near the umbilicus (belly button)
therefore males have the 'butts' hanging out and the females have a longer tail
the easiest way to tell, esp. with younger hamsters whose spaces between their vents isn't as pronounced yet, is that the male's private part looks like the opening of a little tube... while the female's private part looks more like a pucker.

Thanks Becci,
The pics and diagram were great and very helpful but unfortunately they will be copyrighted so I have had to remove them, you can't take any chances these days. The lawyers come after your butt in a flash!
Laura is currently working on our own versions at this very moment  

Here is a picture that Catherine kindly sent us to help in sexing a hamster. It shows the typical way in which the fur feathers or fans out at the rear end of a male dwarf hamster, which helps to distinguish it from a female.

Here is Laura's diagram to help sex dwarf hamsters. We are also trying to get pictures, but I find dwarfies very difficult to get good pictures of as they are rarely still for a second, so the pics are never very well focussed. Ours also never sleep on their back, not that we ever see anyway.
The dad is getting a bit aggressive towards the babies now, especially if we put a tasty snack in, such as a peeled grape, the poor babies didn't get a look in. So we are going to have to split them up pretty soon.

sorry

Quoted from becci

sorry

Hey, Becci no problem at all. I've done it myself many times. It's just that when it's your own site, it seems a lot more serious.
With your artistic talent copyright won't ever be an issue, I'm sure you'd be able to knock up a better version of most things in minutes anyway

The scent gland is just not noticable on hamsters that young. With a full grown adult male it seems huge. The two openings on a female are closer together. Becci describes it well. The female opening seems to pucker. I think it looks square.  The male opening looks like a round dot. There is an actual gap between the two openings. The testicles are internal with dwarfies so there is no bulge the way some animals have them. There can be a small fold that makes a male look female. The female babies have a definite opening. Females never have fur that feathers out at the back. If you have a baby with 'feathers' it is a boy! It is really hard. I have some that I cannot tell until they are older. Sexing hamsters, especially babies is more of an art than a science. Separate the boys as you are sure of them and trust Sunny's judgement. He knows who they are. Post pictures maybe we can help.  Do the best you can and hope you get it right.

Well, today we had a go at sexing our baby hamsters. It's not so easy in the flesh.
We think we have 5 boys and 2 girls. We will recheck tomorrow and try to get some pics for our experts to give an opinion.
We also got our glue gun so they are all set up in new homes, the two baby groups on plastic bins - with shelve! The parents in a cage and Trouble in  a new plastic bin.
Our dwarves must think "what is going on, we seem to move house every few day?"
I'm sure they will enjoy a bit of stability over the next few weeks, and we will think carefully about the separtion via a mesh, with only supervised couple time  
Diane has updated the Blog with the events of the last few days with the hamster family.
I suspect we will be keeping all of our hamsters, and certainly doing our best not to have any more litters.

It is hard to let them go. They don't mind being moved. I sometimes shuffle cages just to give variety. Although some hamsters never move, but that is because I like them where they are. You have about two weeks to sex the babies before it becomes urgent. Do the best you can. It is really hard. They don't always resemble the pictures in the books. We don't always match the pictures in the anatomy books either.

We did a re-check of the hamster's nether regions today as we weren't 100% sure that they were all sexed accurately.  It's a lot harder to do in reality despite how obvious the differences seem on paper!

We think we have got one wrong - we had one boy who is now a girl, so popped her in the cage with the other girls and they seem to be getting on OK.  We'll have to do another few checks I think as they grow more over the next couple of weeks.  Can't risk more pups and would feel terrible if we gave any hamsters away that might already be pregnant!

its good you're keeping tabs on them... keep up the vigilence , its worth it

Usually it is a 'boy' that turns out to be girl. It is really hard to tell. I have come to find one of a group of brothers sitting there with that look on her face. "Look what I did" as she nurses a litter of babies. When my neighbour wanted two boys for her daughter I held them a little longer than usual and I made sure they were boys. Ones that we are not sure of the Pet Store sells as a single hamster. This is working because the hamster bonds with its people. Keep checking, you still have time to correct mistakes. They come in season at 6 weeks. Even Dwarfies can't mature faster than that!

Catherine - I hope you dont mind but I just learned how 2 do animation and used your animals as my first attempt, here are ones I made. You dont have to use then, I just made them for fun. If you would like to though then just tell John

Laura, those are adorable, please we must use them. I look forward to the days when I can do stuff like that. Pigbert and Jonathan really are the cutest and sweetest. They photograghed so well. Of course Jonathan likes to have her picture taken. Who would have thought that little 3in lizard would grow up to be such a character. When I have my own camera I will be able to show you pictures of her antics.

Yes, Jonathan and pigbert are real show-offs it seems, what great pictures! Glad you like them.

I swear the babies change gender in the hamster basket on the way over to the pet store. I can leave home with 6 males and get there with 5 males and one female. Some are just not obvious. So where can we use the new pictures you have done. Would they work for my avatar? I am open to whatever works. Got to run, Christmas dinner awaits(turkey, turkey, turkey, yes!) and the company of good friends. Gemma is an 8 year old animal lover who hopes to own a good many animals some day, but currently has two of my dwarfies.