Both types of orioles build impressive, sock-like nests out of grasses and other plant fibers. Baltimore orioles tend to build nests high up in the trees, while orchard orioles build their nests at varying heights above ground, the Cornell Lab reports.
The female orioles build their nests, weaving together the fibers for about a week until they are complete. Baltimore orioles build in three phases, starting with the outer structure, then creating a bowl inside the nest before lining the bottom with downy feathers. Orchard orioles also line the bottoms of their nests, but you can often see the eggs through the nest when standing below.
The orioles are not particular about nesting materials, using any long, stringy materials they can find, whether its plant material or not, Parke said. In fact, Four Rivers has an oriole nest that is made entirely of plastic, weaved together from items such as fishing line, floss and plastic grasses like we use to fill Easter baskets.
Baltimore orioles often build their nests in elm trees, but also nest in cottonwood and maple trees, according to the Cornell Lab. Orchard orioles are less particular about their nesting locations, building nests in a wide variety of trees, including ash, cottonwood, elm, magnolia, maple, oak, pecan and spruce trees.