CALLIOPE HUMMINGBIRD. Stellula calliope (Gould)

Field characters—Smallest of the hummingbirds in the region. Throat of male with long, lancet-like feathers (pl. 46a) of a striking lavender iridescence, the whole on a white background; back and top of head green; flanks tinged with buffy. Female with back and top of head iridescent green; lower surface grayish white strongly huffy tinged, but no bright rufous on base of tail as in the female Rufous; outer tail feathers broad-ended instead of narrow as in Rufous. Voice: A faint lisping tweez-e-zeet-zee, given when one individual is pursuing another; females when foraging utter a faint seet.

Occurrence.—Common midsummer visitant to high Transition and Canadian zones on both slopes of Sierra Nevada; observed from middle of May until September 1. Seen by us in Yosemite Valley only in May and June. Frequents alder and willow lined cañons and forest glades, foraging chiefly about castillejas and wild currant blossoms.

The Calliope Hummingbird is the smallest species of bird known to occur in California. Its average weight is only about 3 grams (1/10 of an ounce) which is about half that of an Anna Hummingbird, or of a kinglet or bush-tit. Yet this midget is a far migrant. It visits the Yosemite region only in summer; it spends the winter months entirely south of California, and some individuals of the species even go as far south as the City of Mexico and beyond.

Compared with most summer visitants the Calliope Hummer is a late arrival in the region. At Mono Lake it was first seen in 1916 on May 21, a single male bird being observed. Another was seen two days later. On the west slope the earliest record of the bird we have is for May 14 (1919), when a male was seen at Hazel Green. This late time of arrival is probably related to the lack earlier in the season of suitable forage. The appearance of Calliope Hummingbirds in numbers in the vicinity of Chinquapin in 1915 was coincident with the abundant blossoming there of a wild currant (Ribes viscosissimum). The stay of these birds is not prolonged into the fall. The bulk of the crop of nectar producing flowers is gone by early August and we find also that most of these hummingbirds have gone by that time. On September 1, 1915, a single individual, the last definitely identified for the season, was seen on the slopes of Mount Clark. The most favorable localities found by us in which to observe these birds were in the vicinity of Chinquapin and Mono Meadow, where certain sun-facing slopes were covered by heavy growths of wild currant.

Adult males of all our species of hummingbirds have on their throats a patch of iridescent feathers of greater or less extent, known as the gorget, the display of which forms a part of the spring courting performance. The distinctive peculiarities of the gorget as to color and extent are set forth by us under the field characters for each species. The males of most species of birds perform before the females during the mating season, and in some of those species which have little or no ability from a vocal standpoint, as is the case with the hummingbirds, the behavior is striking. The courting performance of the hummingbirds takes the form of a special course of flight, distinctive for each species. That of the Rufous is over a semicircular path in a vertical plane, and is repeated many times in rapid succession; that of the Anna is performed in more deliberate manner over a high and narrow U-shaped course; while that of the Black-chinned is on a short horizontal line over which it moves back and forth time after time. The nuptial flight of the Calliope is somewhat like that of the Rufous, but less vigorous and not so extensive or so continuous, two or three swoops being the rule.

In the Calliope Hummingbird the individual feathers of the gorget are long and lancet-like (pl. 46a), and their lavender iridescence is set forth in fine contrast by a white background. John Gould, the most famous student of hummingbirds, named the bird appropriately, stellula, meaning the little star. When the male Calliope is excited, as when in chase of a rival, or in courting flight, these slender feathers are raised so that they stand out prominently from the other feathers on the throat.

The nuptial flight of the Calliope Hummingbird was seen by us only a few times. In Yosemite Valley on May 31, 1915, a male and female were seen in a patch of blossoming chokecherries. The male mounted into the air a short distance and swooped down past the female, making a slight metallic sound at the bottom of the arc. Flights of similar sort were seen at Mono Meadow in mid-June but were not accompanied by any sound audible to the human ear. Other male hummingbirds, notably the Anna, when thus performing, produce a loud metallic sound at the moment of reaching the lowest point in the downward swing.

Male hummingbirds are not known to take part in any of the duties of nesting. In fact the location of a male seems to have no relation to that of a female or of an occupied nest. Soon after the mating season the males of the migratory species begin the southward migration; this is evidently true of the Calliope. No male of this species was seen by us after the end of June.

At Hazel Green, Chinquapin, and Mono Meadow the males held rather fixed positions in the wild currant thickets. Each individual presided over a certain definite territory, invasion of which brought prompt pursuit of the intruder who was usually quickly put to rout. The squeaky notes of most hummingbirds, and of the Calliope in particular, are more noticeable during one of these pursuits than at any other time.

A male seen in a cut-over clearing near Chinquapin was found to have his 'beat' on a warm sheltered slope. Several high twigs within a 50-yard radius were occupied in succession. He regularly appeared on a certain one which we kept under observation for some time. While perched there his head turned about almost constantly from side to side, and occasionally he would glance upwards. From time to time he would dart off rapidly, only to return and take position on one or another of the perches.

The males of all our hummingbirds are accustomed to harass birds many times their own size. A Calliope at Mono Meadow was seen to put a Wright Flycatcher to rout, the latter seeking seclusion in a ceanothus thicket. In Yosemite Valley another was seen driving at a Western Robin that was on the ground. The hummer would mount as much as 30 feet into the air and then dash down at the robin. Even Red-tailed Hawks are sometimes 'attacked' by these pugnacious midgets.

At Chinquapin on May 19, 1919, a female Calliope Hummingbird was seen during the late afternoon hovering about the lichen-covered trunks of red firs and Douglas spruces in the cañon of Indian Creek. She was evidently gathering nesting material, but her nest site was not located since she took a course directly up toward the top of one of the trees and was lost to sight.

The hummers at Mono Meadow were active throughout the day and until after sundown. On the evening of June 19, 1915, at this place, 2 males and a female were seen foraging when the crepuscular sphinx- or hummingbird-moths had already begun to fly. In Yosemite Valley, early on the morning of May 17, 1919, a male Calliope was seen perched on a dead stub, in an oak and cedar thicket. The bird was catching flies and from time to time would dart out, pewee-like, after passing insects.

Like other hummingbirds the Calliope is often attracted by red objects. Whether this is a voluntary action based on esthetic appeal, or a reflex based on food-getting instinct, is problematic. At Chinquapin, on June 14, a female of this species darted into the front of our open tent and poised with seeming interest before a red-labeled baking powder can on the table. Then the bird went out into the sunshine, but it returned again twice before finally going away. Two of our three August records of this species were of individuals which were attracted in the same manner, the object being a red handkerchief in one case, and a sweater of the same color in the other.