Blue-headed Vireo, Vireo solitarius
Note: this post, while published, is a work in progress, as are all posts in this series, My Photo Life List. My goal is to photograph every species of bird that is seen on a regular basis here in Michigan, working from a list compiled by the Michigan chapter of the Audubon Society. This will be a lifelong project, that I began in January of 2013, and as I shoot better photos of this, or any other species, I will update the post for that species with better photos when I can. While this series is not intended to be a field guide per se, my minimum standard for the photos in this series is that one has to be able to make a positive identification of the species in my photos. The information posted here is from either my observations or the Wikipedia, the online free encyclopedia, however, I have personally shot all the photos appearing in this series.
Blue-headed Vireo, Vireo solitarius
The blue-headed vireo is a Neotropical migrating song bird found in North and Central America. There are currently two recognized sub-species that belong to the blue-headed vireo. It has a range that extends across Canada and the eastern coast of the United-States, Mexico and some of Central America. It prefers large temperate forests with a mix of evergreen trees and deciduous under growth.
As the name suggests, the blue-headed vireo is characterized by its blue-grey head and bold yellow wing bars. Both sexes are very similar in plumage and size. Juveniles also have a similar plumage.
The blue-headed vireo has similar plumage year round and does not drastically change its appearance during the breeding season. It can be characterized by its olive-green upper body, two bold yellow wing bars down the edge of its wing, and a deep blue-grey crown from which it gets its name. The juvenile plumage of immature blue-headed vireos is not distinct but very similar to the adult plumage. While this bird’s appearance is similar to the closely related Cassin’s vireo (Vireo cassinii), the Cassin’s vireo can be differentiated by its lighter yellow patches, a smaller, thinner bill, and a brownish-grey crown. There is little to no sexual dimorphism between males and females as both are similar in plumage coloration and size.
Like most Vireos, the blue-headed vireo is a relatively small bird with a length of 126–148 mm (5.0–5.8 in). The wingspan is usually found to be around 200–240 mm (7.9–9.4 in) and their weight is typically 13–19 g (0.46–0.67 oz).
The average lifespan of the blue-headed vireo in the wild has been measured to be approximately 7 years and 5 months.
Native to North America, the blue-headed vireo enjoys a large breeding range that extends over an immense area of Canada and northern United States. The breeding range of V.s. solitarius extends from northeastern British Columbia across Alberta, Saskatchewan, Manitoba, Ontario and Quebec and down to southern Pennsylvania and New Jersey. At the end of the breeding season, the blue-headed vireo migrates south to its overwintering area.
Blue-headed vireos prefer to breed in cool temperate forests, which in the southern part of its breeding range are found at higher elevations. Evergreen forests with spruce, fir, hemlock, and pine mixed with deciduous growth such as alder shrubs, willow shrubs, poplar, birch or maple trees are the habitat of choice. During the winter, blue-headed vireos inhabit mixed woods of pines and hardwoods. They are also found in coastal and flood plain swamps and low shrubby thickets.
Year round, even during the breeding season, population density is somewhat low and spread out. Overwintering population densities are usually found to be lower than in the breeding season. The density of the population ultimately depends on the type of forest being inhabited.
During migration, blue-headed vireos are often found to flock with groups of different sparrow species but rarely with members of its own species.
Blue-headed vireos are mainly insectivorous birds but are also known to eat fleshy berries and fruit. They are equipped with short, strong bills used for processing insect prey with a tough carapace such as beetles. Foraging usually occurs in the mid level of trees. A foraging blue-headed vireo will hop from branch to branch on the same or to an adjacent tree and will then fly towards its prey to capture it. Typical prey consist mostly of caterpillars, butterflies and moths but may also include tree bugs, stink bugs, beetles, bees, ants, flies, dragonflies, grasshoppers, crickets, spiders and, on some occasions, snails. Fruit feeding occurs primarily during migration and overwintering, especially when overwintering in more tropical regions where fruit is more abundant or if the insect populations are low. This large and varied diet is an example of an opportunistic feeding strategy, allowing the blue-headed vireo to be plastic in its ability to adapt to resource availability.
When arriving to the breeding ground in mid-April, male vireos will hold large, individual territories that can range from 1.5–6.6 hectares (3.7–16.3 acres). Females will choose a male to mate with depending on the male’s ability to defend and control a large territory. While defending their territory from other males, the male vireos will sing a primary song to attract females. Undecided females can usually be seen flying along the edges of competing male territories; usually this will force the two males into direct conflict for the right to copulate with the female.
Once a female has approached a suitable mate, the male will perform a series of mating rituals. Typically, these rituals involve the male building a courtship nest for the female. The courtship nest is not a full nest but is most likely an attempt by the male to display his ability to gather resources. Once the pair is established, the courtship nest is abandoned. Mating does not occur for approximately 2 weeks after pair has been established. During this time, the male and the female will cooperatively build a breeding nest which is typically formed between forking mid-level branches of evergreen and deciduous trees and are composed of twigs and foliage. Breeding nests are not reused in following breeding seasons.
In one breeding season, a female will lay 3–5 eggs at a rate of 1 egg per day. Eggs are creamy white with brown or black spots and are 17–23.1 x 13.3–15.8 mm (0.055–0.075 in x 0.04–0.05 in). Eggs are incubated for approximately 14 days after being laid. Once hatched, infants are highly altricial, often having little to no downy feathers. Infants open their eyes during day 5 or 6 and will begin to fledge after 14 days for a total chick-rearing period of 28 days. Once the young are able to leave the nest, the parents will split the juveniles and separate. Juveniles are usually dependent on the parent to provide food for approximately 1 month after leaving the nest. If the nest is destroyed or a mating pair produces a failed brood, an attempt to re-nest may occur but this ultimately depends on when the brood fails. If the brood fails early on in the season, there is a higher chance that the pair will re-nest, if later, the pair will often separate and not attempt a second brood.
Blue-headed vireos have a low nesting success rate, with about 10–30% of hatchlings surviving. Common predators of the blue-headed vireo eggs and chicks include blue jays, crows, and squirrels.
Often, when a nest is attacked by a blue jay, the male and female will execute coordinated attacks on the approaching predator. This usually involves one partner swooping towards the blue jay while calling the mate who will then execute a second attack. Blue-headed vireos have also been known to nest close to nesting raptorial birds that do not prey on them. It is thought that they use the raptors as protection from squirrels that are, in turn, hunted by the these bird of prey.
The largest contributor to the low nesting success rate of the blue-headed vireo is most likely the parasitic brown-headed cowbird. These birds will often lay their large eggs over the top of the existing brood, causing the parents to feed the cowbird which will ultimately starve the infant Vireos.
On to my photos:
This is number 169 in my photo life list, only 181 to go!
That’s it for this one, thanks for stopping by!