Final answer:
The bird with a white belly and black mask described nests on the ground and uses cryptic camouflage to blend into its environment. Ground-nesting birds such as this have eggs that mimic their surroundings for protection. Brightly colored birds, like the robin with its red breast, use their plumage for territorial displays rather than camouflage.
Step-by-step explanation:
The bird described in the question nests on the ground and has distinct markings such as a white belly with two dark bands and a face with a white pattern and a black mask. These features are an example of cryptic camouflage, a type of coloration that allows an organism to blend in with its surroundings to avoid detection by predators and to sneak up on its prey. Ground-nesting birds, like the one described, often have camouflaged eggs that resemble their environment, providing protection against predation.
In the case of the southern masked-weaver bird, which constructs elaborate nests in trees, this represents a commensal relationship where the bird benefits from the tree's structure without causing it harm. Birds like robins, on the other hand, have bright coloring such as a red breast not for camouflage but to display and defend their territory.