Stay visible, stay calm and do not chase upward
Your first job is to become the most reassuring thing your bird can see. Stand where you have a clear line of sight, keep your movements slow, and talk or whistle exactly as you do at home, using the phrases and sounds it answers to indoors. Do not climb the tree, shake branches or aim a hose upward, because a frightened bird reads all of that as a predator approach and will usually fly to a higher or more distant perch. If a crowd gathers, ask people kindly to step well back and keep dogs away, since a ring of strangers staring upward makes coming down feel far more dangerous to the bird.
Put home at the bottom of the tree
Bring the bird's own cage outside and set it at the base of the tree with the door wide open, favourite food visible inside, fresh water, and a familiar perch or toy placed where the bird can see it from above. If the bird has a bonded companion bird, bringing that companion outside in a secure cage can help, because contact calls from a trusted flock mate carry more weight than any recording. Position the cage so the bird has a clear, sloping flight path down to it rather than a steep vertical drop, which many pet birds are reluctant to attempt, and step back enough that your presence does not block that path while staying close enough to close the door calmly if it enters.
Use food, routine and timing in your favour
Call at the times your bird is normally most active and hungry, especially early morning and late afternoon, and repeat the sounds you use when you present its favourite treat at home. Rattle the treat container, show the food, then place it in the cage rather than throwing food upward, which scatters and rarely reaches the bird. If the bird edges down branch by branch, let it take its time and resist moving in early, because one hasty grab at a low branch often sends it straight back to the top. As light fades, note the exact tree if it settles to roost, keep the cage in place below if it is safe to do so, and be back before dawn when it will be hungry and more willing to descend.
Know when to bring in more help
If the bird stays out overnight, is a young or hand-reared bird with little outdoor stamina, or the weather turns cold, wet or very windy, widen the effort rather than relying on one tree. Tell neighbours on surrounding streets, share a clear photo and description locally, and check nearby gardens, rooftops and lower shrubs at first light, because an exhausted bird often comes down lower the next day and may be found on the ground. Contact local vets, rescues and bird groups in case someone else spots or catches it, and keep returning to the last seen spot with the cage and familiar calls. If he moves off before he comes down, KinsLe's Lost Pet Alert System gives the search a second front: neighbours watching the map can spot him, and whoever does can get word to you through his profile while you keep eyes on the tree.