Pups are born pink with their eyes and ears closed. Their skin is very thin. You can see if they have milk in their stomach, sometimes called a milk bean. Eye color can be determined at birth. Black eyes, wine eyes, and pink eyes. An experienced breeder may be able to tell the difference between chmchm, chmch, uwduwd, and dd eye types. Newborn pups weigh about 3-4g each. Pups should gain about a gram a day for the first 5 weeks of their life.
On day 2 gerbils will start to gain some pigment if the are dark colored.
On day 3 their ears begin to unfold. As they age their skin starts to build up pigment, allowing you to identify some colors and patterns.
Each day they will gain more pigment as the hair starts to grow in.
Around day 8 is when gerbils begin to grow in their fur. Around day 10 it is easiest to sex your gerbil pups. This is not always a super reliable way of sexing pups, and I would not write it in stone. Males can be identified by their larger scent glands and the spacing between their genitals and anus or anogenital distance. Females can be identified by nipple rings around all eight of their teets and their small scent glands and shorted anogenital distance. The nipple method isn't always super reliable on its own, some males still have "ghost nipples" which can fool you. Typically males only have 2-6 of these ghost nipples, if they are present.
During week three you may notice your pups ambling around the tank, before their eyes open. Around day 17 the gerbils start to open their eyes. It is important to not force the eyes open. It may take two or three days for their eyes to open. If after day 20 the eyes haven't opened you can gently brush them with a moist towel. If the eye or eyes still fail to open, the pups might have malformed or missing eyes, though this is extremely rare. In 10 years of breeding I've only had 3 pups ever that were missing eyes, and it was noticed at birth.
During this week they also start eating solid foods. You may even catch them eating poop, which is normal and helps them digest their own food.
Pups are eating solid food, weaning and beginning to figure out how the water bottle works. Make sure the bottle is low enough that the pups can reach it.
It rarely happens but towards the end of week 4 and start of week 5 a pregnant mother might attempt to evict her pups. She may chase and bite them, or kill them. This is abnormal behavior of a stressed mother. The pups and father should be removed immediately to protect the pups and prevent more pups. The female should be retired from breeding, and I would not breed any of her off spring.
By week five the pups should be weaned. Pups should weigh about 35g when they turn 35 days old. At this age they are old enough to be sexed. They are still quite young and absolutely need an adult to care for them. This age is a good age to introduce pups to lone adults.
This is the week pups are at higher risk for getting sick. They are no longer nursing and receiving antibodies from their mother. Keep a careful eye on them for any signs of illness.
Week 6 - 8
Pups are young and still have many pup like behaviors. Breeders may choose to adopt out pups as young as 6 weeks, however gerbils pups benefit from remaining with their family or adults. Its during this time that gerbils really learn how to interact with other gerbils. Its important for pups to be with other adult gerbils so that they learn how to be social.
Week 9 - 12
Week nine is when gerbils start to mature and take on more adult like behaviors. They start to become resistant to being introduced to new gerbils. They also start forming social bonds with each other and establishing dominance.
Newborn pup with white "milk bean" showing through the skin.
Day old pups are pink, and darker colored gerbils like black and agouti might have some pigment already.
Two day old pups begin to darken.
Three day old pups the ears begin to unfold. Spotting patterns are visible on darker colors.
Day four ears are unfolding. Some pups both ears are unfolded some might have only one. Dark colors like black and agouti are very dark.
Day five all ears are unfolded.