But a cockatiel would be easier for a dog to take down. It's pretty easy to teach, and I would also encourage you to enroll in an obedience class and find a good trainer. Your dog can be trained to leave the birds alone. Don't give up on him when he's at an age where behavior is so very easy to mold. As with any dog and small creature, never leave the two alone.
Any dog is a predator and has the capability to kill anything it regards as a prey item.
We have a doberman, racing pigeons, and chickens. My doberman was taught NOT to mess with the birds. Even after training I would be very careful. It's as simple as that. Let your pup know it is not acceptable to you, the alpha, to chase your birds.