bats at halloween

There are two orioles common to our great state of Iowa. While the Baltimore and Orchard orioles have much in common, there are a few differences.

The Baltimore oriole males are bright orange and black (see picture on this page). The females are a more subdued yellow-green and black. During spring and fall migration, Baltimore orioles can be attracted to your yard with sugar water, grape jelly or orange slices since they eat much nectar and ripe fruit during migration. The sugary foods are more readily converted to fat, and that is used for energy during long flights. During the summer months, their diet changes more to insects. Insects are rich in protein, and that is needed to help their young grow.

Baltimore orioles prefer to nest in deciduous tree in open forests or forest edges. They have adapted well to human presence, and will nest in parks, back yards and orchards. Many know the hanging pouch nest of the oriole, but they are hard to find hidden by leaves high in the trees. The female attaches the nest to a forked branch, and then “weaves” a nest 3 to 4 inches deep out of grass, grapevine bark, horse hair, plastic, twine and even fishing line. She may even use materials from an old nest in the new one. Here she will lay 3 to 7 pale grayish or bluish-white eggs with darker blotches. The males are very defensive of their nest site, and will chase off any potential predator.

The population of Baltimore orioles has been declining slightly possibly due to deforestation, insecticides, and artificial lights during nighttime migration.

Male Orchard orioles are darker orange/rust and black in color. The females are yellow-green like the Baltimore oriole females. They seem to prefer living and nesting along open woodland river edges. The female also builds a pouch nest high in a tree, but they are far less defensive of their nest space. The bottom of their nests is very loosely put together, and sometimes you can see the eggs through the bottom of the nest. The female lays 4 to 6 eggs that are blue or gray in color with darker markings. In good habitat, many Orchard orioles may nest in the same tree. Their easy-going attitude does make them more susceptible to brown-headed cowbirds, which is one of the reasons a slow decline is taking place in their populations. Habitat loss and insecticides are also reasons for the decline.

Like the Baltimore oriole, the Orchard oriole eats nectar, pollen, and insects. Sometimes they may even become a pollinator for some tropical plants in their wintering range. Insects make up most of their diet during the year.

A short walk at a local natural area or park is all you need to find orioles. So get outside and enjoy all nature offers.

Photos courtesy of Larry Reis