I can tell you neither are 6 weeks. the bigger one is at the most 5 and the younger one is about 4 weeks. baby has been plucked due to lack of feathers on the head across the shoulders.
there is quite a difference in size,the large one was born first, then another egg or two was laid, and they either a)didn't hatch or b)they died, then the youngest one came along which = the difference in size.
at this age you should be introducing pellets(crushed)seed, water, and millet.
millet is the first thing you should put into the cage.
also add perches low into the cage,and toys so they can learn to perch, and play
my birds are climbing at 3-4 weeks of age, and are eating by the time they are 5-6 weeks.
3 times per day for feeding,(3-8 cc's) did the breeder use Kaytee? you should always use what the breeder was using to avoid any intestinal upset, which you don't want.
make the formula not thick but not runny, around 104 degrees(yes it's that hot), but NO hotter, as it will burn their crop.
you must pre-boil the water for at least 10 minutes to kill any bacteria in the water prior to feeding.
this is one of the best sites out there for raising cockatiels and babies
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