Rivoli's Hummingbird Life History

Habitat

Habitat Forests

Rivoli’s Hummingbirds inhabit pine-oak forests in mountainous areas of the Southwest, usually between 5,000 and 9,000 feet elevation. Rivoli’s is sometimes present at higher or lower elevation when flowers (or feeders) are available. Dense forests, where flowers are fewer, attract this species less than forest edges and gaps, where flowers are more abundant. These large hummingbirds often nest along streams, where flowers are plentiful. Key tree species in their typical Sonoran and Madrean habitats in the United States include ponderosa pine, Chihuahua pine, Mexican stone pine, alligator juniper, Arizona alder, Colorado white fir, quaking aspen, Arizona cypress, Arizona sycamore, Douglas-fir, and Arizona walnut. In Mexico and Central America, Rivoli’s occupies similar habitats and sometimes descends to lower elevations during periods of cold weather.

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Food

Food Nectar

Rivoli’s Hummingbirds drink floral nectar and also consume small insects and spiders, which they glean from plants or catch in the air. Their bills permit them to reach nectar of long flowers, which is not accessible to hummingbirds with shorter bills. Most Rivoli’s Hummingbirds in the United States forage by “traplining,” moving quickly and regularly between several patches of blooming flowers, giving the plants time to produce more nectar. However, in some cases, Rivoli’s will defend an especially productive plant, such as a large agave (century plant), against smaller hummingbirds that attempt to feed there. Rivoli’s also feed on nectar of thistles, red columbine, bouvardia, butterfly bush, Indian paintbrush, beardlip penstemon, Jacob’s ladder, rose of Sharon, vervain, fuchsia, lion’s-ear, bellflower, Indian pink, and Lemmon’s sage, as well as other Salvia species. South of the United States, Rivoli’s feed on nectar of these species and of various species of cactus, mistletoe, iris, and betony. Like many small forest birds, they also consume the sugary water excreted by scale insects (in the genus Strigmacoccus), nicknamed “honeydew.”

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Nesting

Nest Placement

Nest Shrub

The female selects a horizontal branch, often on a tree overhanging a stream, usually 20 feet or higher above the ground (sometimes as low as 10 feet or as high as 89 feet), and places the nest on the branch well away from the trunk.

Nest Description

The female constructs a tight, small cup of leaves, feathers, and mosses, attaching lichen around the exterior using spiderweb. Nests average about 2.2 inches across and 1.7 inches tall, with interior cup 1.3 inches across and 1 inch deep.

Nesting Facts

Clutch Size:2 eggs
Egg Length:0.6-0.7 in (1.4-1.7 cm)
Egg Width:0.3-0.4 in (0.9-1.1 cm)
Incubation Period:15-19 days
Egg Description:

White, smooth-surfaced, tiny oval eggs weighing less than a gram.

Condition at Hatching:

Helpless and naked.

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Behavior

Behavior Hovering

In the northern part of their range, Rivoli’s Hummingbirds nest in spring and summer, when flowers and insects are most abundant. No courtship display is known. Rivoli’s is assumed to have a promiscuous mating system, like other hummingbird species, with both males and females mating with multiple partners and no pair bonds established. Females build and defend the nest and raise the young without help from males. Males sometimes defend feeding territories around specific plants, but in most cases, both sexes forage at widely separated plants over the course of the day, a foraging behavior known as “traplining.” Blue-throated Mountain-gems dominate Rivoli’s Hummingbirds at preferred flowers, but Rivoli’s may dominate smaller species at times. However, most observations indicate that Rivoli’s interact peaceably with other species. On cool nights, Rivoli’s go into torpor, lowering their body temperature to conserve their energy, a trait shared by most montane hummingbirds.

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Conservation

Conservation Low Concern

Rivoli's Hummingbirds are fairly numerous, but almost nothing is known about their population trends. Partners in Flight estimates a combined global breeding population of 2 million Rivoli's and Talamanca Hummingbirds (which until 2017 were combined into a single species, “Magnificent Hummingbird”). Partners in Flight rates Rivoli’s Hummingbird a 12 out of 20 on the Continental Concern Scale, indicating a species of low conservation concern. Habitat destruction is the main conservation concern for this species.

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Credits

Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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