The little boy can pick up his umbrella and try to use it to protect the bird from the rain. Or, if the little boy has clothes or other useful covers, he can also use them to protect the birds. The little boy can also take the bird directly under a nearby tree or shelter to provide him with a warmer and drier environment.
Little boys can help birds find better habitats, such as nearby caves or tree holes with dense leaves. If the little boy can't help the bird directly, he can also ask for help, such as finding a nearby wildlife protection organization or a local animal rescue center.
No matter which method the little boy chooses, he should respect the life and natural behavior of the bird and should not try to change its natural state.