When it comes to the construction of the nest, we think of grass, dirt, feathers and twigs, as mentioned in several of the above nest types. In fact, all of them are shared by “fabrics” in nest architecture. We could add to this list, that may seem like a strange objects: guano, spider, snake skin, shells, saliva, hair, even human artifacts, such as string, plastic, buttons, laces and jewelry! Each of them has a purpose, believe it or not.
For example, manure helps the disguise the smell of nestlings, thus tricking predators. Saliva acts as a super-glue. Insects and spider silk add tensile strength and can repel rain. Nuthatches smear pitch around the entry hole of their nest, and then rub ants in the pitch; the combination is both a chemical and a mechanical deterrent to ward off marauders.
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