Which migratory bird builds mud nests on cliffs and under bridges?

Which migratory bird builds mud nests on cliffs and under bridges?

• A. Common raven
• B. Japanese white-eye
• C. Cliff swallow
• D. Short-tailed pygmy tyrant

Answer: (C)

Bird nesting behavior and habitat choices often reveal a lot about a species. Cliff swallows are famous for building nests out of mud pellets, which they press into place to form cup-shaped structures that cling to vertical surfaces like cliff faces and the undersides of bridges. They typically nest in colonies, so these nests are often seen crowded together on man-made structures and natural cliffs. This mud-nest, vertical-surface, colonial lifestyle is a hallmark of cliff swallows, and they are migratory, traveling between breeding grounds in North America and wintering areas in the tropics. The other birds don’t share this combination of mud construction and attachment to vertical surfaces: ravens use sticks in trees or on cliffs; Japanese white-eyes build smaller nests in shrubs or trees; pygmy tyrants nest in shrubs or tree cavities.