One of our most favorite and plentiful birds at our feeders here in Tucson. The 3-1/2 inch long Black-chinned is closely related to the most prevalent hummer of the eastern United States, the Ruby-throated. They are so similar that the females cannot be distinguished from each other in the field. The male Black-chinned has a black chin (gorget) that when seen in just the right light is bordered in iridescent purple, a white collar and a dark tail. The female is green above, whitish below, and her tail has white corners. Both sexes sport a white spot behind each eye. The females are similar to the female Costa’s Hummingbird, but their bills are longer, they are grayer below, and they have throats that may vary from nearly clear to dimly streaked or spotted. When hovering, both the Costa’s and Black-chinned pump their tails up and down, and flick them open.
Photo by Doris Evans
The Black-chinned arrives in Arizona in March after wintering in Mexico. It is most commonly found along rivers and in cities and towns. But it is usually absent from the desert. It stays around until September, but the males generally exit the state by mid-summer, leaving the females and juveniles behind. In the summertime, the bird ranges from British Columbia, south along the Pacific coast, west to the Rockies, and south to northern Mexico and northern Baja, California. It winters south of south-coastal Texas, northern Baja, California, southeastern California, and northern Mexico down to Guerrero, Distrito Federal, and Michoacan. It has been seen as far out of its range as Louisiana, Nova Scotia, Florida and Massachusetts.
Black-chinneds feed mostly on the nectar of plants. The flowering of certain food plants coincides with their arrival in the spring. In Phoenix, the Black-chinned did not breed until irrigation and exotic plants were introduced. By the time the hummers arrive, they can feed on many plants that are already in bloom, including agave, tree-tobacco (Nicotiana glauca), citrus trees, lantana, nasturtium, shrimp plant (Beloperone guttata), and others. At least 37 different plants provide food for this little hummingbird. It does not have any innate preference for red flowers, but this may be a learned behavior. As with most birds, scent does not play a large role in locating feeding sources. The shape of the flower could be a feeding stimulus. Of the many plants favored by Black-chinneds, besides those mentioned previously, are Hall’s honeysuckle, scarlet larkspur (Delphinium cardinalis), ocotillo, paloverde, ironwood, Texas buckeye, and chuparosa.
In addition to plants, the Black-chinned will eat pollen. If you feed hummingbirds in Tucson, you know how much they love man-made nectar from feeders. Another food source is found in insects, for which they will dart out like a flycatcher from a prominent perch.
F. Bene studied Black-chinned Hummingbirds in 1947 and concluded that they establish three kinds of territories. The females ensconce themselves in a nesting preserve. This is found in a breeding locality that includes a nest site, one or more perches, a feeding site, and a roosting site. Both sexes visit a mating area. Males defend their own feeding preserves where they guard not only food sources, but also perches and roosting sites. Sometimes males may visit the female preserves, but they do not feed there. Just before and for only a few days after copulation, the male roosts near the female, but he arrives there only after his last meal of the clay. In the nesting preserve, the intensity of the defense increases as the breeding period progresses. In the male preserve, an area of only from 3 to 6 meters in diameter is defended. After breeding, this may increase slightly to 7 to 15 meters, and may include a couple of feeders.
Although the local food supply probably determines these territories initially, if the territories shift at a later date, the nest site, perch, or roost may change and bring about a shift of the area guarded for food. The male Black-chinned centers his territory about a roosting site. He always returns to it at nightfall, except for the few days he spends roosting close to a courted female. As the youngsters become independent, they stay on the parental territories until they migrate south.
When the females arrive in the male’s display area, the aerial courtship display begins. The male makes a series of swooping, pendulum-like, 30 meter long arcs, passing very close to the female at the bottom of the arc, and ending about 5 meters above her. Sometimes the arc becomes a narrow, horizontal figure eight (8). A loud whistling buzz accompanies this spectacular flight, probably made by air passing through the tail or wings. Four thin, vibrant notes or a liquid, drawn-out, pulsating note with a plaintive quality may be heard. At the apex of each swing, the male may hover and emit a mechanical sound that is likened to the sound a bathing bird makes, evidently caused by patting his wings together below him. These acrobatics continue until shortly after the eggs are laid.
Nest building, done by the females, takes from 3 to 7 days. Two pure white eggs are laid, usually one or two days apart from April to June. In Arizona, the nest is often found from 1 to 3 meters above the ground, in the fork of a branch overhanging a small stream or dry wash. They like willows, cottonwoods, sycamores, and olive trees in towns. The nest is a round cup of plant down, about 1-1/2 inches across and one inch high. It is coated with strong, flexible spider’s silk. The use of the underside of the leaves of sycamore trees give it a distinctive yellowish cast. Sometimes budscales, stamens, and fragments of flowers, leaves or bark may be attached to the outside.
The female incubates the eggs by herself for 13 to 16 days. The youngsters leave the nest after about 20 days, but stay close by for a couple days while the female continues to feed them. Gradually, the young learn to forage on their own. This is a somewhat awkward process of repeatedly visiting odious plants, probing fertilized plants that have no nectar, and overlooking plants full of nectar. Two or three broods may be raised in one season. The female may begin incubating eggs in a second nest while still feeding youngsters in the first nest. Instances of “double brooding” have been reported in California, Arizona and New Mexico.
Trademark Notice: "InfoNatura", NatureServe, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.
InfoNatura: Animals and Ecosystems of Latin America [web application]. 2007. Version 5.0 . Arlington, Virginia (USA): NatureServe. Available: http://www.natureserve.org/infonatura. (Accessed: February 12, 2013 ).