As you can see here they can make quite a mess. I use a warm wash cloth to whip the access food off of the young. This little Shakh Sharli Pigeon squeaker was neglected by it's young parents. You will notice that the baby bird formula in the container is setting on a large sock that is full of rice. I sew the end together with string and warm the rice sock in the microwave for 3 min. It keeps the formula warm. If the food cools it can be very bad for the young. 

I usually do a big feeding in the am as they are quite hungry and the crop is empty. Then another smaller feeding around noon and one more before bedtime. At around 3 weeks of age I will place them on a white cotton towel with small bird seed. (white millet mostly) and introduce them to seed. It might take time but using your finger you can pick or peck around the seed as if you are a bird eating. If you have other young that are tame you can just have the younger ones watch the older ones and soon they catch on. but you will still have to hand feed. At this stage I start making my mix a bit more runny so they get more water with what little seed they do eat. 

If they have started to eat mainly seed you will have to show them water. Use a small water dish. I use a Gerber's baby glass jar as the little ones can not knock it over as easy. Dip their beak into the water to show them where it is. It will take more time to teach this and may take days for them to catch on. I always check the babies crops to see how much seed to water ratio is in the crop. If it feels thick and hard they will need some water. 

The best feeding method I have found is by using a 3cc Syringe with a rubber eye dropper. Cut off the end making an opening for the birds beak. You can find syringes from most feed stores and vets. I use a small 3 cc syringe so the food does not get cold too fast. The rubber piece is from Wal Mart in the baby section. Drill out part of the inside of the syringe so the food can flow through smoothly. I just use the rubber part of the dropper. Cut out a hole in one end and attach onto the syringe. After a short time the plunger will start to stick so I have started applying a small amount of cooking oil on it so that it is lubricated and will move smoothly.

Kaytee Exact Hand Feeding Formula for all baby birds has worked great for me. (ALWAYS use warm water) I paid $12.99 for an 18 oz can. When I hand feed 3 pigeon squeakers I use just over 1 can. It's not cheep to hand feed but if you love to raise birds....

Below you can see me feeding a few day old Parlor Roller. I found this little one nearly dead and very cold. The parents had accidentally pushed both babies out of the nest so I got to raise them. They are so attached to me that every time I go into the bird room they run over and climb up onto my shoes and beg for attention. 
Quite often I will have to hand feed young doves and pigeons. Sometimes from the parents abandoning them or a young pair that has not had experience raising offspring. I often like to have bonded birds as they make excellent pets. Parlor Roller Pigeons are known to accidentally knock their young out of the nest so I will have to step in and hand feed and care for them. It is not as hard as you think but it takes time and practice. In the picture you will notice the syringe on the top has a piece of fish tank tubing attached to the end. I use this one only when there is an emergency and the young need water, electrolytes or is just not eating at all. I will gently insert the tube into the mouth and into the throat and down just enough to pass the breath hole. Then you can push in the warmed electrolyte - water into the crop. DO NOT OVER FEED! The young will aspirate moisture into the lungs and die or become sick later. Be very careful as the back of the throat is very easy to tear or damage. I only use small soft tubing. I got this syringe at my dentist's office and the tubing can be found at pet stores. But make sure it's the soft, flexable kind. 
Whitby Win​gs Farm and Aviary