How do some animals build elaborate structures, such as beaver dams and bird nests?

Animals have unique abilities to construct their habitats or create shelter in ways that are often adapted to their specific needs. Some animals build elaborate structures, such as beaver dams and bird nests, which can take a considerable amount of time and effort to construct.

Beavers are known for building elaborate dams that can alter entire ecosystems. These dams are constructed out of mud, sticks, and logs, which are held together with the beavers' saliva. The dams can be several feet high and span hundreds of feet across a river.

Birds also construct elaborate nests to protect and incubate their eggs. Each species has a unique nest-building behavior, and some birds will spend weeks building intricate structures using materials such as twigs, grass, and mud. Some species of birds, such as the weaver bird, build elaborate hanging nests using intricate weaving techniques.