Button quail are the smallest quail. They average about 1.4 ounces as adults. Comparing them to other birds. American Budies average around 1.3 ounces so they are very close except the budgie has far more wing and tail feathers making it look larger (English budgies are a different story obviously). Button quail eggs are also larger than a budgies egg so the chciks of a budgie are smaller to start with. They both grow very rapidly and can leave nest or brooder at 6 weeks approx. Buttons are larger than many finches. Hope that helps.
