Once upon a time, about 3 decades ago, taxonomists combined 2 species of orioles into the
Northern Oriole species. However, in the dance known as “name that species,” these folks reversed their decision about 15 years ago and reinstated the earlier split between Bullock’s Oriole (the more western species) and Baltimore Oriole (the more eastern species). Originally, the treeless Great Plains provided a barrier that didn’t permit the intermingling of these 2 species. However, as Americans moved to and through the Great Plains, they planted deciduous trees around farms and in towns, inviting the 2 species to expand their ranges toward each other. These 2 species will hybridize where their ranges overlap—primarily in the Great Plains. However, striking differences in appearance, molt patterns, vocalizations, and DNA support the separation, despite the hybridization.
In Colorado, the Bullock’s Oriole is by far our most common oriole. A medium-sized, songbird, the orange, black, and white adult male flashes large white wing patches and (as my favorite nature writer, Pete Dunne, says) a distinctive bohemian head patterns—an orange face bedecked with a black beret, black wraparound eyeglasses, and a black goatee. Females and immatures aren’t nearly as spiffy, with grayish brown to yellowish upperparts and yellow or dull green underparts becoming pale on the belly.
Orioles are part of the larger Icterid family, along with blackbirds, grackles, cowbirds, and meadowlarks. Their scientific name is Icterus bullocksii. Icterus derives from the Greek word for “jaundice” or “yellow;” bullocksii (as well as the common name) honors William Bullock, who helped to identify this species in 1827. Oriole comes from modern Latin (is that an oxymoron?) for “golden.”
Bullock’s Orioles inhabit Colorado between May and August after wintering in central Mexico and Central America. They nest in deciduous trees, such as cottonwoods and oaks, by rivers, streams, and lakes. They also can be found in urban parks, if water is present. They eat mostly insects (butterflies, larval insects such as caterpillars, grasshoppers), fruit (blackberries, raspberries, cherries—and cut oranges at bird feeders), and nectar (either from flowers or from special feeders that look like HUGE hummingbird feeders). When feeding, these birds exhibit impressive acrobatic skills for such a large bird—hopping and fluttering, hanging head down and stretching their necks to pluck prey or fruit.
Oriole nests rank among the most interesting songbird nests. Made primarily by the female, she weaves a pendulous, drooping nest out of hair (most often, horsehair), fibers, grass, twine, ribbon—I’ve even seen one constructed primarily of fishing line. (One decent use for the carelessly discarded fishing line that can be found too often around popular fishing spots.) She then lines the inside with fluffy cottonwood or willow seeds and feathers. These nests hang from the forks of limbs, near the end, which helps to prevent depredation by climbing mammals such as squirrels and raccoons. A clutch of, on average, 4 – 5 eggs hatches in approximately 11 days. Both parents feed the young and nestlings leave the nest about 2 weeks after hatching. The fledglings tend to stick with their parents for several days after fledging, begging noisily. Sometimes, though, groups of recent fledglings coalesce and are fed by parents from different nests.
Despite their striking colors, Bullock’s Orioles can be surprisingly difficult to spot in the wild. However, their voices give them away every time. Their song is a mixture of rich whistles and harsh rattles; their call is a very distinctive rapid chatter. So this summer, if you find yourself around water with tall deciduous trees, listen for a lively, bouncy song full of rich whistles and dry rattles. That means the orioles are out and about!
To hear the song and the chatter and find links to photos, visit