Animal Diversity Web

Ge­o­graphic Range

Ca­lypte anna breeds along the west­ern coast of North Amer­ica. The breed­ing range stretches from British Co­lum­bia through Ari­zona to the west­ern edge of New Mex­ico. How­ever, the non-breed­ing range is ex­pand­ing. This range ex­tends from the Alaskan coast to north­ern Mex­ico. (Rus­sell, 1996)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

Ca­lypte anna have made their home in open woods, shrubs, gar­dens, and parks. Dur­ing breed­ing sea­son they are re­stricted to Cal­i­for­nia and a habi­tat sep­a­ra­tion is es­tab­lished be­tween males and fe­males. Dur­ing this time males typ­i­cally move to more open habi­tats in­clud­ing canyon sides and hill slopes. Fe­males, on the other hand, live in trees, in­clud­ing ever­greens and oaks. Anna's Hum­ming­birds also ex­pe­ri­ence dif­fer­ent habi­tats with the chang­ing sea­sons. Dur­ing the sum­mer months they move to higher el­e­va­tions, and in win­ter they move to lower al­ti­tudes. (Johns­gard, 1997; Rus­sell, 1996)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• forest
• scrub forest

• Other Habitat Features
• urban
• suburban
• agricultural

Phys­i­cal De­scrip­tion

Anna's hum­ming­birds are medium sized, stocky hum­ming­birds. They are sex­u­ally di­mor­phic. Males and fe­males both have a bronzy, green dor­sal area that is glossy in ap­pear­ance and a dull, gray ven­tral re­gion. They have a medium length bill and a broad tail. Male C. anna have a brightly col­ored rose throat area and crown and a dark tail. Fe­males are gen­er­ally a dull mix­ture of gray/white or gray/brown, but may have a patch of metal­lic red or pur­plish feath­ers in the cen­ter of the throat area. The tail, tipped with white, is metal­lic green in the cen­ter with the ex­te­rior tail feath­ers dark­en­ing to black. Ju­ve­nile male and fe­male birds both re­sem­ble adult fe­males but there are some slight vari­a­tions. Im­ma­ture males have brightly col­ored feath­ers on the throat and crown and a less rounded tail, while young fe­males are a pale brown and pos­sess no metal­lic col­ored feath­ers on the throat re­gion. (True, 1983; Unitt, 2000)

• Other Physical Features
• endothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• male more colorful

• Range mass

  4 to 4.5 g

  0.14 to 0.16 oz

• Average length

  100 mm

  3.94 in

• Range wingspan

  114 to 121 mm

  4.49 to 4.76 in

• Average basal metabolic rate

  0.1175 W

  AnAge

Re­pro­duc­tion

Male and fe­male C. anna only come to­gether to mate. Fe­males are re­spon­si­ble for build­ing nests, in­cu­bat­ing the young, and rear­ing the brood. The sea­sonal win­ter rains start mat­ing sea­son, and it is dur­ing this time that males move into their breed­ing ter­ri­to­ries and fe­males start the nest build­ing process. The nest is bound to­gether with spi­der webs and is lined with soft ma­te­r­ial such as plants, feath­ers, or hair. The out­side of the nest is draped with bark, dead leaves, lichen, or paint chips, in an at­tempt to cam­ou­flage. The ac­tual mat­ing rit­ual com­mences when a fe­male en­ters a male's ter­ri­tory. After the male spots the fe­male he does a se­ries of dives in the air and be­gins to chase her. Dur­ing this chase, the fe­male leads the male to­ward her nest­ing area and perches. Dur­ing cop­u­la­tion the fe­male spreads her tail, twist­ing it slightly down­ward and to the side. In order for fer­til­iza­tion to occur, the male must mount her back. Dur­ing this time, he may seize her crown feath­ers with his bill and twist his ab­domen and tail down her side. Cop­u­la­tion lasts 3 to 5 sec­onds. (Rus­sell, 1996; True, 1993)

• Mating System
• polygynandrous (promiscuous)

The breed­ing sea­son com­mences be­tween No­vem­ber and De­cem­ber and con­tin­ues until some­time be­tween April and May. Dur­ing this sea­son C. anna can have two broods. Each brood con­sists on av­er­age of 2 white, el­lip­ti­cal eggs, which are laid one day apart. Fe­males in­cu­bate the eggs for 14-19 days, and chicks are in the nest an ad­di­tional 18 to 23 days. The hatch­lings are al­tri­cial, barely re­sem­bling the adult form. Their eyes open on the fifth day after hatch­ing. When the hatch­lings are six days old they are fully cov­ered with down. After the nest­ing pe­riod the young re­main de­pen­dent on the mother for a few ad­di­tional days, but within one or two weeks they achieve total in­de­pen­dence. There is no male parental care. In­ter­est­ingly, im­ma­ture C. anna start to show ter­ri­to­r­ial be­hav­ior when they are quite young. After leav­ing the nest, Anna's hum­ming­birds have a ten­dency to re­main in pairs, usu­ally sib­lings. How­ever, by fall most young C. anna sep­a­rate and main­tain their own ter­ri­tory. (Rus­sell, 1996; True, 1983)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• oviparous

• Breeding interval

  There may be two broods produced per breeding season

• Breeding season

  The breeding season commences between November and December and continues until sometime between April and May.

• Average eggs per season

  2

• Average eggs per season

  2

  AnAge

• Range time to hatching

  14 to 19 days

• Range fledging age

  18 to 23 days

• Average age at sexual or reproductive maturity (female)

  1 years

• Average age at sexual or reproductive maturity (male)

  1 years

Fe­male Anna's hum­ming­birds in­cu­bate and feed their young until they reach in­de­pen­dence. There is no male parental care.

• Parental Investment
• altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

Anna's hum­ming­birds live an av­er­age of 8.5 years. (Rus­sell, 1996; True, 1983)

• Range lifespan
  Status: wild

  8.5 (high) years

• Average lifespan
  Status: wild

  8.5 years

• Average lifespan
  Status: wild

  98 months

  Bird Banding Laboratory

Be­hav­ior

Anna's hum­ming­birds are not so­cial an­i­mals; they are ter­ri­to­r­ial and will dive at any­thing that en­ters their ter­ri­tory, no mat­ter what size. These birds mi­grate be­tween sum­mer and win­ter ranges. They are ac­tive dur­ing the day and may be­come tor­pid at night to con­serve en­ergy. (Rus­sell, 1996; True, 1993)

• Key Behaviors
• flies
• diurnal
• motile
• migratory
• solitary
• territorial

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Ca­lypte anna has four sources of food: nec­tar from flow­ers, sap from trees, sugar-wa­ter mixes from feed­ers, and very small in­sects and spi­ders. Anna's hum­ming­birds are equipped with long, nar­row bills and have a body adapted to hover over flow­ers. These two fea­tures allow them to eas­ily ex­tract nec­tar. While the bird is hov­er­ing over the flower it ex­tends its tongue and in­serts it into the flower. Ca­lypte anna is most at­tracted to long, tubu­lar flow­ers, with a red, or­ange, or vi­o­let hue. Some com­mon hum­ming­bird flow­ers in­clude: aza­leas (Rhodo­den­dron ar­borescens), fuch­sia (Fuch­sia ar­borescens), scar­let morn­ing glory, hon­ey­suckle (Lonicera sem­per­virens), and im­pa­tiens (Im­pa­tiens bal­sam­ina). How­ever, C. anna feeds most fre­quently on: chap­ar­ral cur­rent (Ribes mal­vaceum), fuch­sia-flow­ered goose­berry (Ribes spe­cio­sum), great-berried man­zanita (Arc­tostaphy­los glauca), mon­key-flower (Dipla­cus longi­forus), pitcher-sage (Salvia spathacea), Cal­i­for­nia fuch­sia (Epi­lo­bium), west­ern columbine (Aqui­le­gia for­mosa), and In­dian war­rior (Pedic­u­laris den­si­flora). Apart from flow­ers, Anna's hum­ming­birds find food in the air by cap­tur­ing fly­ing in­sects or eat­ing in­sects trapped in spi­der webs. They also use holes in trees to ex­tract sap. (Rus­sell, 1996; True, 1983)

• Primary Diet
• herbivore
  • nectarivore

• Animal Foods
• insects

• Plant Foods
• nectar
• pollen
• sap or other plant fluids

Pre­da­tion

Ca­lypte anna has many preda­tors in­clud­ing west­ern scrub-jays (Aph­e­lo­coma cal­i­for­nica), Amer­i­can kestrels (Falco sparverius), greater road­run­ners (Geo­coc­cyx cal­i­for­ni­anus), and curved-billed thrash­ers (Tox­os­toma curvi­rostre). As a re­sponse to these preda­tors, C. anna has de­vel­oped two pri­mary de­fense mech­a­nisms. First, when a preda­tor at­tacks a nest the fe­male will mob the as­sailant. She will do this by hov­er­ing in front of the in­vader, beat­ing her wings rapidly, and at­tack­ing the head and back. The sec­ond mech­a­nism is to avoid low lying food sources, C. anna pre­fer high feed­ers and flow­ers. (Rus­sell, 1996; True, 1983)

• Known Predators

  • western scrub-jays (Aphelocoma californica)
  • American kestrels (Falco sparverius)
  • greater roadrunners (Geococcyx californianus)
  • curved-billed thrashers (Toxostoma curvirostre)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Pol­li­nates many species of flow­ers, such as the chap­ar­ral flora of Cal­i­for­nia. The chap­ar­ral flora has a large va­ri­ety of species that have adapted to Anna's hum­ming­birds. These species of plants have de­vel­oped win­ter growth and flow­er­ing to fit the breed­ing and feed­ing pat­terns of C. anna. These species, along with oth­ers, have evolved di­rectly along­side Anna's hum­ming­birds. (True, 1983)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no neg­a­tive im­pacts of Anna's hum­ming­birds.

Con­ser­va­tion Sta­tus

The Anna's Hum­ming­bird pop­u­la­tion has been spread­ing and grow­ing since the 1950's. They have ex­panded north and east from their orig­i­nal habi­tat. The flow­ers and feed­ers of sub­ur­ban gar­dens have en­abled them to ex­tend into these dif­fer­ent re­gions. Ca­lypte anna are very com­mon within most of their range; thus, there are reg­u­lar sight­ings. In ad­di­tion, they adapt well to sub­ur­ban areas.

(Kauf­man 1996) (Kauf­man, 1996)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

Hum­ming­birds are the only birds that have adapted to fly back­ward and for­ward. Their wings can beat in­cred­i­bly fast. In fact, when hum­ming­birds hover, their wings can beat from 22 to 72 times per sec­ond. This rapid mo­tion causes them to ex­pend most of their en­ergy in flight; to make up for this nu­tri­tional de­pri­va­tion hum­ming­birds can con­sume half of their body weight in food per day. Most species of hum­ming­bird mi­grate dur­ing sea­sonal changes; how­ever, Anna's and Allen's hum­ming­birds are the only two species that re­main in the United States and Canada year-round. Ca­lypte anna is the largest hum­ming­bird that in­hab­its the west coast.

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Abi­gail Lobas (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Johns­gard, P. 1997. The Hum­ming­birds of North Amer­ica. Lon­don: Christo­pher Helm.

Kauf­man, K. 1996. Lives of North Amer­i­can Birds. New York, New York: Houghton Muf­flin Com­pany.

Rus­sell, S. 1996. Anna's hum­ming­bird : Ca­lypte anna No. 226. F Gill, ed. Birds of North Amer­ica. Philadel­phia: Amer­i­can Or­nithol­o­gists' Union; Acad­emy of Nat­ural Sci­ences.

True, D. 1983. Hum­ming­birds of North Amer­ica. Wash­ing­ton D.C.: Smith­son­ian In­sti­tu­tion Press.

True, D. 1993. Hum­ming­birds of North Amer­ica: At­tract­ing, feed­ing, and Pho­tograph­ing. Al­bu­querque: Uni­ver­sity of New Mex­ico Press.

Unitt, P. 2000. "Ocean Oasis: Ca­lypte anna" (On-line). Ac­cessed March 21, 2001 at http://​www.​oceanoasis.​org/​fieldguide/​caly-ann.​html.