Costa’s hummers are among the most beautiful of North American birds. The sun catches the iridescent feathers of the male’s head and flared gorget and flashes from a metallic violet to blue, magenta, royal purple or even green depending on the angle of the light rays.
Both males and females are small. Only the Calliope hummingbird is smaller than the Costa. In North America it is the second smallest hummingbird in North America at 3-1/2 inches long with a wingspread of 4-1/2 inches.
Male---The male has a brilliant metallic amethyst purple head that can appear violet-blue, greenish or magenta in certain lights. The gorget is long, flared, and extends far down the sides of his neck. It is the only bird with such markings in North America. The rest of the upperparts are a dull metallic bronze-green.
Female--- Females are nearly indistinguishable and may not be safely identified from the Black-chinned females but it is grayer above and whiter below.
They lack the flashy colors of the males, and are green and gray birds, usually with an immaculately clear throat, although they sometimes show some metallic violet flecks. Ii you are trying to decide what female hummer you have feeding at your feeder, look at the tail as they speed away. Any hint of rufous coloration in the tail eliminates the possibility that the suspect bird might be a Costa’s hummingbird.
Young---The immature look like the females. When hovering, both species nervously flick their tails open, and pump them up and down. It is extremely difficult to visually differentiate female and immature Costas from Black-chins in the field.
The male Costa’s likes to perch on a small rise behind our house in the top third of a small Palo Verde tree. From there, he faithfully guards a hummingbird feeder attached to the porch beam. He’s fearlessly chased other hummers, and even harassed a thirsty Gila Woodpecker that dared to taste “his” nectar.
Like our other hummingbirds, the Costa’s dines on nectar, spiders and insects. It is often seen at feeders.
The Costa’s feeds on many different shapes of flowers. It gleans nectar from chuparosa and sages (salvia), fairy dusters, coral bean, desert lavender, larkspur, boxthorn, desert, penstemon, desert willow and boxthorn. It especially enjoy the flowering ocotillo and we see them foraging at young ocotillo, possibly gathering tiny insects as well as nectar.
The calls are more distinctive. The chip call of the Costa’s female is a very high, light and sharp tik or tip, which is often rapidly repeated to produce a twitter. The chip call of the Black-chinned is a low pitched, softer, slurred tew or tchew. It is rarely run together in a series, and the Black-chins are altogether much less vocal. The male Costa’s make two types of sounds when not flying - a single whistled note and a much shorter two or three note whistle. During U-shaped diving displays that may start from a height of 30 to 60 meters, the male utters a two second loud shrill whistle as it reaches the bottom of the dive. After the long whistle, the bird immediately rises and flies in a broad horizontal circle until it reaches its starting point.
Like the Anna’s Hummingbird, the Costa’s undergoes only limited migration. It winters mainly along the lower Colorado River, northwest to Palm Springs, and south to the tip of Baja California. From October on, it is increasingly being seen here in Pima County for the winter. In the spring, this little hummingbird is one of the first spring migrants, often arriving in late January. It nests from central California, southern Nevada, and southwestern Utah south to the Santa Barbara Islands, southern Baja California including all near-shore islands, southern Arizona, southwestern New Mexico, Sonora and Sinaloa. It is frequently seen from late February until the end of May, by which time it has finished breeding in the desert areas and presumably migrated to the coast of California or back to Baja California. In spite of these tendencies to migrate over a relatively small area, it has been sighted quite a long ways from home. There have been at least eight sightings from Oregon. Occasionally they are seen in Texas.
We regularly see the Costa’s Hummingbird at our feeders from about October until mid-May. Throughout winter a few Costa’s Hummingbirds can be spotted at feeders in southern California and Arizona. As winter rains awaken desert flowers in late January, they start moving from Baja and the northwest coast of Mexico into the deserts of southern California and Arizona.
As the “ice breaks on the Santa Cruz River” in mid-May when the temperature soars to above 100°, the desert becomes even drier and the flowers diminish. The Costa’s Hummingbird then disappears. No one seems to know where they go during our hot summers. Banding records are of no help in determining where they go. Not one banded Costa’s has ever been recovered away from its banding site. Lake Havasu State Park wildlife officials have reported large numbers of Costa’s passing there in May. They may follow the blooming of flowers caused by snowmelt and move up the Colorado River into the cooler mountains around Kingman. Perhaps the birds scatter back into Mexico. One researcher found their numbers increased in southern Nevada, southern California, northwestern Arizona, and extreme southwestern Utah from mid-March to mid-June.
Whenever they return in the fall, we know that the weather will start to lose its summertime intensity. In October, the Costa’s Hummingbird reappears in Arizona to feed on the flowers that bloom after the summer monsoon rains.
We are always glad to see them as these little feathered gems are among the most beautiful of birds in North America.
Courtship begins shortly after the Costa’s males arrive on their large 1/2 square mile nesting territory, the displays begin.
He put on quite a show when courting a female this winter. He sat like a monarch on his throne at the top of a mesquite, and sang a loud song, announcing his ownership of his territory to whoever was listening. She sat on an open branch of a Palo Verde, maybe 5 feet off the ground. The next thing we noticed, he was no longer on his high perch, but we heard a prolonged, intense, rising and falling whistle. He repeated it several times, long enough for us to locate him as he dove from higher than our home in an arc that was nearly circular. This display went on for most of the day, sometimes accompanied by a loud boom that might have been made by air rushing through his wing or tail feathers as he dove. The male perches at the tips of the highest available vegetation between dives.
A day later we saw him swinging back and forth for a distance of about 3 feet in front of a perched female in a different Palo Verde. She twittered at him as he darted directly at her, backing up and coming at her from a variety of angles. After a short time, she flew off to the north across the desert, with her suitor in close pursuit.
The breeding habitat of the Costa’s includes deserts, washes, mesas, or hills where sages, ocotillo, chuparosa, yuccas, and cholla cacti grow abundantly. When breeding, it is relatively independent of water and utilizes dryer habitats than any other hummer in North America. This is probably true in wintering habitats as well, although this has not been documented. The males and females appear to share the breeding territory equally.
Nesting in Arizona begins early, with well-developed young seen as early as mid-April. Throughout their entire range, eggs are laid between February and June. There is a record of a late January nesting from San Diego. It has been speculated that the birds may raise one brood in the Borrego Desert in southern California before moving to the chaparral in April to breed again.
Nesting sites, sizes and materials are as varied as the shapes of the flowers that Costa’s uses.
Nesting site--- Nests are found: on vines clinging to rock faces; as low as 3 feet from the ground in thorny shrubs like catclaw acacia; in citrus or palm trees; in cacti like pencil cholla; in tall grasses; or 35 feet off the ground at the end of a cottonwood branch. While they may nest close to water, this is not a firm requirement for this desert hummer.
The female prefers nesting sites in low elevation deserts, such as at Organ Pipe National Monument, southwest of Tucson. She typically nests at some distance from water, with several nests found in one area. The nest is placed in deciduous trees or yuccas from 1 to 9 feet off the ground. Sixteen different trees are known to be used, including oak, alder, hackberry, and willow. Sage, dead yuccas, cacti with branches, or Palo Verde can also be used.
Nest materials--- The female constructs nests in typical hummingbird fashion, with a fibrous framework of stems attached to a support by strong cobwebs. They are lined with soft plant down or feathers. Sometimes the female decorates her nest exterior with bark, paper, lichens, buds, willow or yucca down, and the whole nest is bound with spiders’ silk. Sometimes she leaves it completely unadorned.
Time to construct--- It takes about 2 days to build the nest.
Eggs---Two white eggs are laid about 2 days apart. Incubation must begin with the laying of the first egg as the young hatch a day or so apart. The eggs are incubated for 15 to 18 days. When the young hatch, they are naked and helpless. By the time they are six days old, pinfeathers begin to appear. They are fed every half hour. About 20 to 23 days are required before the young fledge.
One of our Costa males sits in the mesquite tree as the computer keys click out the letters and words of this article. His glittering violet flashes in the blazing sun. What a void he leaves at our feeding station when he wanders off. What a joy he and his mate are when they return!