The Anna’s hummingbird (Calypte anna) is a medium-sized hummingbird native to the west coast of North America. Some key facts about the Anna’s hummingbird include:
- They are one of the most common hummingbirds found along the Pacific Coast.
- They are named after Anna Masséna, Duchess of Rivoli.
- They have iridescent green-red throats and crowns, with gray undersides.
- Males have a striking rose-pink gorget (throat patch).
- Females lack the bright pink gorget.
- Their wings can beat up to 70 times per second.
- They are very territorial and aggressive.
- They have adapted well to human development and can be found in many urban areas.
- They do not migrate and can be found year-round in their range.
- They feed on nectar, tree sap, and small insects.
Some of the most interesting characteristics of the Anna’s hummingbird include their adaptations for feeding, territorial behavior, courtship displays, and ability to thrive around human development. Let’s explore these traits in more detail.
Feeding Adaptations
Anna’s hummingbirds have several interesting adaptions that allow them to feed efficiently on nectar:
- Long, thin beaks – Their beaks are specially adapted for reaching into flowers and accessing nectar.
- Extendable tongues – Their tongues can extend up to two times the length of their beaks to reach nectar.
- High metabolisms – Hummingbirds have very fast metabolic rates that require them to feed frequently throughout the day.
- Ability to hover – They can beat their wings up to 70 times per second, allowing them to hover in place while feeding.
- Preference for red flowers – Their eyes are sensitive to the color red, guiding them to nectar-rich flowers.
These adaptations allow Anna’s hummingbirds to efficiently feed on floral nectar, visiting hundreds of flowers per day. Their long beaks and tongues give them access to nectar that other birds cannot reach.
Territorial Behavior
Anna’s hummingbirds are highly territorial creatures. Males in particular establish territories around nectar resources and nesting sites:
- Males use aerial displays to advertise territories – They perform dramatic display dives up to 130 feet in the air.
- They aggressively defend territories from intruders – Using vocalizations and physical aggression to chase away other males or competing species.
- Territories provide access to food and mates – Controlling prime feeding areas helps attract females.
- Territories are re-established each year – Younger males must establish new territories after older males die off.
- Females also defend smaller feeding territories once nesting – Ensuring reliable access to food while incubating eggs and raising young.
Defending territories is energy-intensive but ensures Anna’s hummingbirds have priority access to essential resources needed for survival and reproduction. This behavior likely evolved to maximize feeding and mating opportunities.
Courtship Displays
Male Anna’s hummingbirds use elaborate courtship rituals to attract females:
- High-speed dive displays – Males climb 30-130 ft then dive toward females at speeds up to 60 mph, producing loud chirps with their tail feathers.
- Aerial “pendulum displays” – Males fly in wide vertical arcs above females, swinging from side to side like a pendulum.
- Rapid hovering-and-chasing displays – Males will rapidly hover in front of females, then chase them in fast horizontal flight.
- Songs and vocalizations – Males sing complex songs of chirps and squeals during courtship.
- Iridescent throat feathers – Males flash their iridescent throats at females during displays.
These impressive sights and sounds stimulate females and demonstrate a male’s athleticism and health. Females observe displays before choosing a mate. The most dramatic, persistent males tend to achieve the most matings.
Adaptability to Human Environments
Anna’s hummingbirds display a unique adaptability to human development, exploiting new food sources:
- Take advantage of gardens and exotic plants – Feeding on ornamental flowers and backyard bird feeders.
- Thrive in urban and suburban areas – As long as some flowers or feeders are present.
- May have higher survival in developed areas – Due to abundant food and water sources provided by humans.
- Likely colonized California with the Gold Rush – Spread north as new towns provided habitat.
- Now found from Baja California to British Columbia – One of the most northward-expanding bird species.
This ability to live alongside humans has greatly expanded the Anna’s hummingbird’s range over the past 150 years. They are now one of the most commonly sighted hummingbird species along the West Coast.
Physical Description
Anna’s hummingbirds display striking physical features including:
- Small size – They average 3-4 inches long and 4-6 grams in weight.
- Short, straight bills – The bill is mostly black, adapted for feeding on nectar.
- Iridescent throat feathers – Males have bright pink throats, while females have light gray throats.
- Green and gray plumage – Females and juveniles are mostly gray-green on the head and back, with gray undersides.
- Males have rosy-pink crowns – When the light hits them just right, they glow.
- Long, pointed wings – Their narrow, pointed wings enable agile flight.
- White tip on tail – Both sexes have white outer tail feathers that flash in flight.
The Anna’s hummingbird’s compact body and specially adapted wings provide excellent aerial agility and allow it to hover with precision while feeding on flower nectar. The bold pink plumage on the males’ throats and crowns make them stand out.
Habitat and Range
The habitats and range of the Anna’s hummingbird include:
- Found along the Pacific Coast of North America
- Range stretches from southern Arizona to British Columbia
- Lives in a variety of habitats including – Suburban neighborhoods, parks, forests, scrublands, mountains, and deserts.
- Particularly abundant in the San Francisco Bay Area
- Does not migrate – Can be found year-round throughout its range
- Has expanded its range dramatically northward over the past century
Anna’s hummingbirds are very adaptable and can thrive in diverse environments as long as flowers, nectar sources, and small insects are available. Their ability to survive cold winters and expand northward has allowed them to become one of the most widely distributed hummingbird species along the Pacific Coast.
Diet
The diet of Anna’s hummingbirds consists mainly of:
- Flower nectar – From blooms of shrubs, trees, vines, and herbaceous plants
- Tree sap – Obtained by boring holes in trees
- Small insects – Particularly spiders and insects found on flowers
- Sugar-water from bird feeders – Provides an important supplemental food source
- Pollen – Provides protein and nutrients
- Algae – Algae growth in tree sap provides an additional food source
Nectar provides the majority of the hummingbird’s diet. Their specialized beaks and extendable tongues allow them to access the nectar of many blooms. Small insects and tree sap provide additional nutrition and energy. Backyard bird feeders make accessible sugar-water solutions that help sustain Anna’s hummingbirds.
Breeding and Nesting
The breeding behaviors and nesting habits of Anna’s hummingbirds include:
- Breeding season lasts from November to June
- Males establish breeding territories to attract females
- Elaborate courtship displays by males
- Females build a small cup-shaped nest out of plant down and spider webs
- Nest is only 2 inches wide and 1 inch deep
- Usually nests on branches of trees and shrubs
- Lays 2 tiny white eggs
- Incubation lasts 14-19 days
- Chicks fledge after 21-25 days
- Mother feeds the chicks regurgitated insects and nectar
- Some pairs may raise 2-3 broods per year
Anna’s hummingbirds breed across a long season from late fall through early summer. This gives them the flexibility to produce multiple broods. The female takes sole responsibility for nest construction and raising the chicks, while the male focuses on courtship and defending his territory.
Migration and Winter Behavior
One of the Anna’s hummingbird’s defining characteristics is that it does not migrate seasonally. Instead:
- Found year-round within its range along the Pacific Coast
- Many birds move partially downslope or to coastal areas in winter
- Males and females establish separate winter feeding territories
- Males are dominant over females at feeders in winter
- Nocturnal torpor helps conserve energy on cold nights – Body temperature drops and heart rate slows
- Builds up fat reserves to survive winter nights and cold spells
The Anna’s hummingbird is well-adapted to survive the relatively mild Pacific Coast winters. By feeding on tree sap, cached insects, and maintained feeders, they can persist even in snowy mountains and northern climates. Their territorial behavior ensures access to essential food supplies even through the lean winter months.
Vocalizations
Anna’s hummingbirds communicate with a variety of vocalizations:
Sound | Context |
---|---|
Short, repeated chatters | Male territorial and courtship displays |
Loud squeaky song | Male courtship display, communicating with mate |
Short squeaks or chip notes | Female signals toward mate or intruders |
Soft tic notes | Begging calls by nestlings to mother |
Whining wing notes | Produced by tail feathers during dives and display |
Vocalizations help communicate territory claims, courtship displays, warnings, and signals between mates and their young. The males’ complex and varied songs are specifically used to charm females.
Threats and Predators
Some key threats and natural predators of Anna’s hummingbirds include:
- Loss of habitat from development
- Pesticides which reduce insect food sources
- Nest predation by jays, crows, roadrunners, squirrels, and cats
- Hawks, falcons, and gulls may prey on adults
- Collisions with windows and buildings
- Artificial feeders may spread disease
- Climate change altering availability of nectar sources
Providing natural landscaping, keeping cats indoors, and implementing “bird-friendly” designs in new buildings can help reduce some of these threats. Most predation is natural, however, and Anna’s hummingbirds remain a thriving species along the West Coast.
Interesting Facts
- Anna’s hummingbirds were named for Anna Masséna, Duchess of Rivoli in the 19th century.
- They produce sounds as loud as 100 decibels – equivalent to a motorcycle engine.
- Their wings beat up to 70 times per second – the fastest of any hovering bird.
- They build nests as small as a 50-cent coin.
- Some males may mate with up to 50 females in a season.
- They have remarkably short legs – they can barely walk, only shuffle along perches.
- They can fly up to 35 miles per hour.
- They have the second-biggest brain relative to their body size of any bird.
- They consume up to twice their body weight in nectar per day.
The Anna’s hummingbird is truly an incredible and unique bird. Their specialized adaptations allow them to thrive in the hummingbird ecological niche along the Pacific Coast.
Conclusion
In summary, the Anna’s hummingbird is a fascinating species with many interesting behaviors and adaptations for feeding, breeding, territoriality, and survival in both urban and natural environments along the Pacific Coast. Their beauty, bold colors, aerobatic displays, and aggressiveness make them one of the most charismatic backyard birds for West Coast residents to encounter. The Anna’s hummingbird’s ability to flourish in human-altered habitats demonstrates their resilience in the face of environmental change. Understanding more about common backyard birds like the Anna’s hummingbird can help us appreciate the wildlife around us and inspire greater environmental awareness and stewardship.