I put a harness on my budgie. Will it still be able to fly?

Have him examined by your veterinarian or by an experienced avian vet. Most birds can fly unless there is an injury or defect in the wings or feathers. A poor clip job may also affect flight, but at 3 years old he should have molted and grown new feathers to replace damaged ones.

Having a playpen or something your birds can rest on while out of the cage is a good idea. Also making sure they can get back into their cage for food and water (and to close it when you're ready for them to be back in) is also best. You may also want to have a bird net on hand to catch them if they aren't super tame and won't go back into their cage. Clipping wings can help make them easier to handle and catch, and if you are unsure how to do this, having a local vet show you before allowing them out and about is best. Making sure the room doesn't have any harmful objects such as fans, open windows, cooking items, etc is best to avoid injury to your birds. If there are sharp objects or things they could be injured on, removing them before allowing your birds out is best.

Congratulations on your new birds! If the flying back and forth is in response to when you are putting your hand into the cage this could be due to fear or being startled. If he is randomly flying throughout the day with no relation to you approaching then it could be him just exercising. Millett is a treat that is very useful in helping gain your budgie's favor as well, so letting them nibble some from your hand or while you touch them if they are comfortable with you touching is helpful in making interaction with you a pleasant experience and can eventually be used to lure them onto your finger or hand!

Patience is best when getting your budgie used to handling. If he has a favorite treat you can offer it every time you approach the cage or every time he sits up on your finger. Once he is comfortable there, you can begin to then offer treats after you pet him, to teach him that this is a rewarding behavior. It can take some time, and if your budgie is too stressed simply take a break and let him calm down a bit before trying again.

Clipping wings can be beneficial if you are letting your bird out a lot to help keep him from escaping or running into things. If you've never clipped his wings before, I highly recommend having a vet do it the first time so that they can show you in person where the wings need to be clipped, how short, and how often. From then on, you can begin to clip the wings on your own following those instructions as well as other tutorials. if you do clip the wing yourself, be sure to have items such as styptic powder on hand in case you accidentally clip too far and need to stop any bleeding.

Have him perch on your finger, then gently place a thumb on his feet to hold him. Allow him to flap as he is being held on your hand. This may show him he doesn't have enough lift to takeoff. You can also hold him over the bed and allow him to gently fly/flutter down onto it a few times. This may also show him he can only fly downwards.

In order for your bird to trust you you will need to work with him daily. If you are worried that he may fly away when you let him out of the cage you can clip his wings so he will not be able to fly. This is a completely painless procedure and the feathers will grow back if you decide at a later date to allow him to fly. This way you can let him out of the cage to explore but won’t have to worry about him getting away. The more interaction you have with the bird the better. Offer him treats while you are working with him so he can start building some trust in you. I would assume that after a month or so of repeated interactions you bird will be much more comfortable with you. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.