Observing Nesting Bullock’s Orioles

June 19th, 2023

Today, out in the field, I observed a couple of male Bullock’s Orioles, Icterus bullock, feeding loud young birds in a lovely lichen cup nest located in a large ash tree. The sounds of the baby birds are what alerted me to the nest location. Sitting quietly, I began to see the two male orioles bringing a variety of food to the nest. One of the males looked like a female at first glance, but upon closer observation, I could see it had a black chin and black on the crown of its head, which females do not have. This young male was a softer lemon color like the female Bullock’s Oriole. This was not the first time I had seen a young male Bullock’s Oriole hanging out with another male. The adult male made no attempts to chase off the other male. When I researched this phenomenon, I could only find a short paragraph describing this. Watching these two males working together to feed the baby birds was interesting and I began taking photos to document what was happening. The female did not show up while I was there, and I wondered if something had happened to her. Adult males training young males of the same species to do the work of the adults, to learn the process of building a nest, vocalize and project the calls and songs that keep a territory and attracts females, is something I have read about in other bird species in tropical places such as the Lance-tailed manakin bird species.

This behavior may have benefits that scientists are still trying to figure out. One of the benefits that may be happening in front of me is that if the female dies, the adult male has someone to help him feed and raise the young. What does the first or second-year male get out of it? Well, maybe it is a training program on how to be a dominant male.

The hanging cup or sack-like nest is intricately woven from many different materials depending on the habitat where the oriole is living. Historically, orioles used horse or any other long mammal hair for binding the nest together, but here in Little Lake Valley the main binding is the long Lace lichen, Ramalina menziesii. Methuselah’s beard, Usnea longissima, and other lichens and moss line the inside of the nest. An article I read from Cornell University describes how a pair of orioles work together to weave a cup or sack nest. One of the pair is on the inside and the other is on the outside. They push the material through and then wrap and push it out again, this made me want to have a camera videotaping this activity in our area. According to an article by “Wild Birds Unlimited” nature shop in Indiana, “The oriole nest is an engineering masterpiece. It is woven with plant fibers, grasses, vines, tree bark, and sometimes yarn or string. It said that one Baltimore Oriole (this is the eastern counterpart of the Bullock’s Orioles and used to be considered the same species) was observed to spend forty hours building its nest with about 10,000 stitches and the tying of thousands of knots all with its beak.”

The Bullock’s Oriole nest in the photographs is not a long sack, as is being described in this article, but even this smaller cup-like version is a work of engineering, well-constructed of woven lichens and with a black string of some type around it. It is well hidden by the Lace lichen that is naturally growing on the tree. Every time I find one of these oriole nests, I am amazed at how vulnerable they seem, yet we do have an abundance of Bullock’s Orioles in Little Lake Valley.