Red And Yellow Swallow Nest. Royalty-Free Stock Photo

Red and yellow mud swallow nest under a bridge. The more primitive species nest in existing cavities, for example in an old woodpecker nest, while other species excavate burrows in soft substrate such as sand banks.[2] Swallows in the genera Hirundo, Ptyonoproggne, Cecropis, Petrochelidon and Delichon build mud nests close to overhead shelter in locations that are protected from both the weather and predators. The mud-nesters are most common in the Old World, particularly Africa, whereas cavity-nesters are the rule in the New World. Mud nesting species in particular are limited in areas of high humidity, which causes the mud nests to crumble. Many cave, bank and cliff dwelling species of swallow nest in large colonies. Mud nests are constructed by both males and females, and amongst the tunnel diggers the excavation duties are shared as well. In historical times, the introduction of man-made stone structures such as barns and bridges, together with forest clearance, has led to an abundance of colony sites around the globe, significantly increasing the breeding ranges of some species. Birds living in large colonies typically have to contend with both ectoparasites and conspecific nest parasitism.[13][14] Old males benefit most from coloniality, since they are able to maintain their own nests and benefit from frequent extra-pair copulations.