These migratory songbirds, including the Baltimore and Bullock’s orioles, travel vast distances between their breeding grounds in North and Central America and their wintering habitats in the tropics. Their diet is highly adaptable and varied, shifting significantly depending on the season and the food sources available in their current location. Understanding these dietary preferences is key to successfully attracting them to a backyard setting.
Natural Diet: Insects and Nectar
Insects form the primary part of the oriole’s natural diet, especially during the breeding season. This protein-rich food source is necessary for the development and growth of nestlings. Orioles consume a wide range of invertebrates, including beetles, grasshoppers, spiders, and adult moths.
Orioles prefer soft-bodied insects and various caterpillars, such as tent caterpillars, fall webworms, and gypsy moth caterpillars, which many other bird species avoid. They are considered foliage gleaners, methodically searching leaves and branches for prey. They may also consume tree sap, which provides a source of sugar when other sweet foods are scarce.
Orioles also consume flower nectar, which provides a quick boost of energy from simple sugars. They are attracted to flowers that offer easily accessible nectar, such as jewelweed, honeysuckle, and trumpet vine. Unlike hummingbirds, orioles often use their pointed beaks to pierce the base of a flower to access the nectar, a feeding behavior known as “nectar robbing.” This sugar-rich component is important as they prepare for long migratory flights.
Natural Diet: Fruits and Berries
Fruits and berries are a significant part of the oriole’s diet, serving as a primary source of carbohydrates and sugars. They prefer dark-colored, ripe fruits, which often have the highest sugar content. Specific wild favorites include:
- Black cherries
- Mulberries
- Elderberries
- Raspberries
- Serviceberries
Orioles often pierce ripe fruit with their beak to access the sweet juices rather than consuming the entire pulp. This preference for soft, sugar-filled fruit is noticeable in late summer and fall as they build up fat reserves for migration. In their wintering grounds, their diet expands to include tropical fruits, such as bananas, figs, and citrus.
Attracting Orioles: Supplemental Foods
Orioles have a strong preference for sweet, high-energy foods, making several supplemental items effective attractants. Grape jelly is an effective attractant due to its high sugar content and color. It should be served in small dishes or specialized feeders, using one or two tablespoons daily to prevent waste. Use plain grape jelly without artificial sweeteners or colors, and clean the feeder daily to prevent mold growth.
Halved oranges are another successful supplemental food, appealing to the birds with their bright color and sugary juice. These citrus halves are typically placed on spikes or specially designed feeders, with the cut side facing up for easy access. Oranges should be replaced every one to two days, especially in warm weather, as they dry out quickly and can attract insects or develop mold.
Sugar water, similar to that used for hummingbirds, is readily consumed and provides a liquid energy source. The standard concentration is one part granulated white sugar dissolved into four parts water. Oriole nectar feeders often have larger feeding ports and perches to accommodate the larger birds. The sugar solution must be changed every few days and the feeder thoroughly washed to prevent fermentation.
Seasonal and Regional Diet Changes
The oriole’s diet follows a cycle based on their life stages and food availability. When they arrive in the spring after migration, they require high-sugar foods like nectar, fruit, and supplemental jelly to quickly replenish energy reserves. This quick energy helps them recover and begin establishing territories.
As the breeding season progresses into summer, the diet shifts toward protein, with insects making up the bulk of their food intake. This protein is necessary for the development of their young, and some backyard feeders offer mealworms during this period. In late summer and early fall, the focus returns to high-sugar and high-fat foods, such as ripe berries and supplemental fruit, to maximize the fat stores needed for the return migration south.
During the winter months in Central and South America, the oriole’s diet relies heavily on the tropical ecosystem. They consume a steady diet of tropical fruits, nectar from flowering plants, and available insects. This flexible diet ensures they have the correct nutrients for every phase of their annual cycle.