Anna's hummingbird

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Anna's hummingbird
Anna's hummingbird.jpg
Male flying in California, USA
Female annas hummingbird hovering.jpg
Female hovering
call of the Anna's hummingbird
CITES Appendix II (CITES)[2]
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Apodiformes
Family: Trochilidae
Genus: Calypte
Species:
C. anna
Binomial name
Calypte anna
(Lesson, 1829)
Calypte anna map.svg
Range of C. anna
  Wintering range
  Breeding and wintering range

Anna's hummingbird (Calypte anna) is a medium-sized bird species of the family Trochilidae. It was named after Anna Masséna, Duchess of Rivoli.[3]

It is native to western coastal regions of North America. In the early 20th century, Anna's hummingbirds bred only in northern Baja California and southern California. The transplanting of exotic ornamental plants in residential areas throughout the Pacific coast and inland deserts provided expanded nectar and nesting sites, allowing the species to expand its breeding range.[3][4] Year-round residence of Anna's hummingbirds in the Pacific Northwest is an example of ecological release dependent on acclimation to colder winter temperatures, introduced plants, and human provision of nectar feeders during winter.[5]

These birds feed on nectar from flowers using a long extendable tongue. They also consume small insects and other arthropods caught in flight or gleaned from vegetation.

Description[edit]

Anna's hummingbirds are 3.9 to 4.3 in (9.9 to 10.9 cm) long with a wingspan of 4.7 inches (12 cm) and a weight range of 0.1 to 0.2 oz (2.8 to 5.7 g).[4] They have an iridescent bronze-green back, a pale grey chest and belly, and green flanks. Their bills are long, straight, and slender. The adult male has an iridescent crimson-red, derived from magenta, to a reddish-pink crown and gorget, which can look dull brown or gray without direct sunlight, and a dark, slightly forked tail. Females also have iridescent red gorgets, although they are usually smaller and less brilliant than the male.[4]

Feather iridescence[edit]

A male Anna's hummingbird displaying its iridescent head feathers.

A male Anna's is the only North American hummingbird species with a red crown.[4][6] Females and juvenile males have a dull green crown, a grey throat with or without some red iridescence, a grey chest and belly, and a dark, rounded tail with white tips on the outer feathers.[6]

The male Anna's hummingbird has a striking reddish-pink crown and gorget, which are strongly iridescent and dependent on the angle of illumination and observation by female or male competitor birds.[6] The iridescence results from large stacks of melanosomes in the feather barbules, occurring as layers separated by keratin.[6] The barbules reflect incident light in the manner of partially-opened Venetian blinds, enabling the iridescence – which varies the head and gorget coloration with the changing angle of light – as a coloration advantage for courtship attraction and territory defense.[6]

Male Anna's hummingbirds with elevated levels of protein in their diet have more colorful crowns and higher iridescence in their head feathers compared to male birds with low protein intake.[7]

Behavior[edit]

While collecting nectar, the Anna's hummingbird assists in plant pollination.[8] There is evidence that Anna's hummingbirds in flight generate an electrostatic charge that would adhere pollen to their beaks and feathers, facilitating transfer of pollen grains to hundreds of flowers per day while foraging for nectar.[9] This species sometimes consumes tree sap.[10]

The male's call is scratchy and metallic, and it perches above head-level in trees and shrubs.[4] They are frequently seen in backyards and parks, and commonly found at feeders and flowering plants. Anna's hummingbirds eat flying insects.[11]

Anna's hummingbirds can shake their bodies 55 times per second to shed rain while in flight, or in dry weather, to remove pollen or dirt from feathers.[12] Each twist lasts four-hundredths of a second and applies 34 times the force of gravity on the bird's head.[12]

Reproduction[edit]

A female incubates eggs in a camouflaged nest.
Two nestlings are fed by a female hummingbird.

Open-wooded or shrubby areas and mountain meadows along the Pacific coast from British Columbia to Arizona make up C. anna's breeding habitat. The female raises the young without the assistance of the male. The female bird builds a nest in a shrub or tree, in vines, or attached to wires or other artificial substrates. The round, 3.8-to-5.1-centimetre (1.5 to 2.0 in) diameter nest is constructed of plant fibers, downy feathers and animal hair; the exterior is camouflaged with chips of lichen, plant debris, and occasionally urban detritus such as paint chips and cigarette paper.[3] The nest materials are bound together with spider silk. They are known to nest as early as mid-December and as late as June, depending on geographic location and climatic conditions.[13][14]

Unlike most northern temperate hummingbirds, the male Anna's hummingbird sings during courtship. The song is thin and squeaky, interspersed with buzzes and chirps, and is drawn to over 10 seconds in duration. During the breeding season, males can be observed performing an aerial display dive over their territories. When a female flies onto a male's territory, the male rises up about 130 ft (40 m) before diving over the female. As the male approaches the bottom of the dive, it reaches an average speed of 27 m/s (89 ft/s), which is 385 body lengths per second.[15] At the bottom of the dive, the male travels 23 m/s (51 mph), and produces an audible sound produced by the tail feathers, described by some as an "explosive squeak".[16][17]

Anna's hummingbirds hybridize fairly frequently with other species, especially the congeneric Costa's hummingbird.[3] These natural hybrids have been mistaken for new species. A bird, allegedly collected in Bolaños, Mexico, was described and named Selasphorus floresii (Gould, 1861), or Floresi's hummingbird. Several more specimens were collected in California over a long period, and the species was considered extremely rare.[18]

The specimens were the hybrid offspring of an Anna's hummingbird and an Allen's hummingbird. A single bird collected in Santa Barbara, California, was described and named Trochilus violajugulum (Jeffries, 1888), or violet-throated hummingbird.[19] It was later determined to be a hybrid between an Anna's hummingbird and a black-chinned hummingbird.[20][21]

Locomotion[edit]

During hovering flight, Anna's hummingbirds maintain high wingbeat frequencies accomplished by their large pectoral muscles via recruitment of motor units.[22] The pectoral muscles that power hummingbird flight are composed exclusively of fast glycolytic fibers that respond rapidly and are fatigue-resistant.[22]

Distribution and population[edit]

Anna's hummingbirds are found along the western coast of North America, from southern Canada to northern Baja California, and inland to southern and central Arizona, extreme southern Nevada and southeastern Utah, and western Texas.[3][4] They tend to be permanent residents within their range. However, birds have been spotted far outside their range in such places as southern Alaska, Saskatchewan, New York, Florida, Louisiana, and Newfoundland.[23][24]

The population of Anna's hummingbirds is estimated to be 1.5 million, and appears to be stable.[1] They are not an endangered species.[1] Among the eight most common hummingbirds in Canada and the United States, only the population of Anna's hummingbirds has been increasing since 1970.[8]

Northern range expansion[edit]

Anna's hummingbirds have the northernmost year-round range of any hummingbird. Birds have been recorded in Alaska as early as 1971, and resident in the Pacific Northwest since the 1960s, particularly increasing as a resident population during the early 21st century.[5][25] Scientists estimate that some birds overwinter and presumably breed at northern latitudes where food and shelter are available throughout winter, tolerating moderately cold winter temperatures.[5][25]

During cold temperatures, Anna's hummingbirds gradually gain weight during the day as they convert sugar to fat.[26][27] In addition, hummingbirds with inadequate stores of body fat or insufficient plumage are able to survive periods of subfreezing weather by lowering their metabolic rate and entering a state of torpor.[28]

While their range was originally limited to the chaparral of California and Baja California, it expanded northward to Oregon, Washington, and British Columbia, and east to Arizona in the 1960s and 70s.[5] This rapid expansion is attributed to the widespread planting of non-native species, such as eucalyptus, as well as the use of urban bird feeders, in combination with the species' natural tendency for extensive postbreeding dispersal.[13][29] In the Pacific Northwest, the fastest growing populations occur in regions with breeding-season cold temperatures similar to those of its native range.[5] Northward expansion of the Anna's hummingbird represents an ecological release associated with introduced plants, year-round nectar availability from feeders supplied by humans, milder winter temperatures possibly associated with climate change, and acclimation of the species to a winter climate cooler than its native region.[5][25] Although quantitative data are absent, it is likely that a sizable percentage of Anna's hummingbirds in the Pacific Northwest still do migrate south for winter, as of 2017.[25]

In the 2017 Vancouver Official City Bird Election, Anna's hummingbird was named the official bird of the city of Vancouver, British Columbia, Canada,[30] where it resides year round through winter.[31]

Gallery[edit]

References[edit]

  1. ^ a b c BirdLife International 2016. Calypte anna. The IUCN Red List of Threatened Species 2016: e.T22688199A93186783. https://doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22688199A93186783.en. Downloaded on 21 March 2019.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ a b c d e Williamson, Sheri (2001). A Field Guide to Hummingbirds of North America. New York, NY: Houghton Mifflin Harcourt. p. 199. ISBN 0-618-02496-4.
  4. ^ a b c d e f "Anna's Hummingbird". Cornell University Laboratory of Ornithology, Ithaca, NY. 2015. Retrieved 10 November 2016.
  5. ^ a b c d e f Battey, C. J. (2019). "Ecological release of the Anna's hummingbird during a northern range expansion". The American Naturalist. 194 (3): 306–315. doi:10.1086/704249. ISSN 0003-0147. PMID 31553208. S2CID 164398193.
  6. ^ a b c d e Giraldo, Marco A.; Parra, Juan L.; Stavenga, Doekele G. (2018-10-08). "Iridescent colouration of male Anna's hummingbird (Calypte anna) caused by multilayered barbules". Journal of Comparative Physiology A: Neuroethology, Sensory, Neural & Behavioral Physiology. 204 (12): 965–975. doi:10.1007/s00359-018-1295-8. ISSN 0340-7594. PMC 6244987. PMID 30298342.
  7. ^ Meadows, M. G.; Roudybush, T. E.; McGraw, K. J. (2012-07-25). "Dietary protein level affects iridescent coloration in Anna's hummingbirds, Calypte anna". The Journal of Experimental Biology. 215 (16): 2742–2750. doi:10.1242/jeb.069351. ISSN 0022-0949. PMC 3404802. PMID 22837446.
  8. ^ a b English, Simon G.; Bishop, Christine A.; Wilson, Scott; Smith, Adam C. (2021-09-15). "Current contrasting population trends among North American hummingbirds". Scientific Reports. 11 (1): 18369. doi:10.1038/s41598-021-97889-x. ISSN 2045-2322. PMC 8443710. PMID 34526619.
  9. ^ Badger, Marc; Ortega-Jimenez, Victor Manuel; von Rabenau, Lisa; Smiley, Ashley; Dudley, Robert (2015-09-30). Gruverman, Alexei (ed.). "Electrostatic charge on flying hummingbirds and its potential role in pollination". PLOS ONE. 10 (9): e0138003. Bibcode:2015PLoSO..1038003B. doi:10.1371/journal.pone.0138003. ISSN 1932-6203. PMC 4589311. PMID 26421845.
  10. ^ Peterson, Roger Tory; Peterson, Virginia Marie (1990). Peterson's Field Guide to Western Birds. Boston: Houghton Mifflin. pp. 216–217. ISBN 0-395-51424-X.
  11. ^ "Anna's hummingbird". Washington NatureMapping Foundation. 2021. Retrieved 26 September 2021.
  12. ^ a b Ortega-Jimenez, VM; Dudley, R (2012). "Aerial shaking performance of wet Anna's hummingbirds". J R Soc Interface. 9 (70): 1093–1099. doi:10.1098/rsif.2011.0608. PMC 3306655. PMID 22072447.
  13. ^ a b "Anna's Hummingbird - Introduction Birds of North America Online". birdsna.org. Retrieved 2019-01-18.
  14. ^ Sheri., Williamson (2001). A field guide to hummingbirds of North America. Boston: Houghton Mifflin. ISBN 0618024956. OCLC 46660593.
  15. ^ Clark, C.J. (2009). "Courtship dives of Anna's hummingbird offer insights into flight performance limits". Proceedings of the Royal Society B. 276 (1670): 3047–3052. doi:10.1098/rspb.2009.0508. PMC 2817121. PMID 19515669.
  16. ^ Clark, C.J.; Feo, TJ (2008). "The Anna's Hummingbird chirps with its tail: a new mechanism of sonation in birds". Proceedings of the Royal Society B. 275 (1637): 955–62. doi:10.1098/rspb.2007.1619. PMC 2599939. PMID 18230592.
  17. ^ Yollin, Patricia (8 February 2008). "How hummingbirds chirp: It's all in the tail". San Francisco Chronicle. Retrieved 10 November 2016.
  18. ^ Palmer, T.S. (September 1928). "Notes on persons whose names appear in the nomenclature of California birds" (PDF). The Condor. 30 (5): 277. doi:10.2307/1363227. JSTOR 1363227.
  19. ^ Ridgway, Robert (1892). The Humming Birds. Washington DC: Smithsonian Institution. pp. 331, 329.
  20. ^ Taylor, Walter P. (1909). "An instance of hybridization in hummingbirds, with remarks on the weight of generic characters in the Trochilidae". The Auk. 26 (3): 291–293. doi:10.2307/4070800. JSTOR 4070800.
  21. ^ Ridgway, Robert (1909). "Hybridism and generic characters in the Trochilidae". The Auk. 26 (4): 440–442. doi:10.2307/4071292. JSTOR 4071292. Retrieved 2008-11-11.
  22. ^ a b Altshuler, Douglas L.; Welch, Kenneth C.; Cho, Brian H.; Welch, Danny B.; Lin, Amy F.; Dickson, William B.; Dickinson, Michael H. (2010-07-15). "Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)". Journal of Experimental Biology. 213 (14): 2507–2514. doi:10.1242/jeb.043497. ISSN 0022-0949. PMC 2892424. PMID 20581280.
  23. ^ "Unusual Hummingbird for Idaho: Anna's Hummingbird – Calypte anna". Archived from the original on 2008-05-16. Retrieved 2008-11-12.. See distribution map on bottom of page.
  24. ^ "Pacific hummingbird found in eastern NFLD". CBC News. 24 January 2011. Archived from the original on 21 November 2012. Retrieved 10 November 2016..
  25. ^ a b c d Greig, Emma I.; Wood, Eric M.; Bonter, David N. (2017-04-05). "Winter range expansion of a hummingbird is associated with urbanization and supplementary feeding". Proceedings B, the Biological Sciences of the Royal Society. 284 (1852): 20170256. doi:10.1098/rspb.2017.0256. ISSN 0962-8452. PMC 5394677. PMID 28381617.
  26. ^ Beuchat, C.A.; Chaplin, S.B.; Morton, M.L. (1979). "Ambient temperature and the daily energetics of two species of hummingbirds, Calypte anna and Selasphorus rufus". Physiol. Zool. 52 (3): 280–295. doi:10.1086/physzool.52.3.30155751. S2CID 87185364.
  27. ^ Powers, D. R. (1991). "Diurnal Variation in Mass, Metabolic Rate, and Respiratory Quotient in Anna's and Costa's Hummingbirds" (PDF). Physiological Zoology. 64 (3): 850–870. doi:10.1086/physzool.64.3.30158211. JSTOR 30158211. S2CID 55730100.
  28. ^ Russell, S.M. (1996). In The Birds of North America, No. 226 (A. Poole and F. Gill, eds). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington DC
  29. ^ Clark CJ, Russell SM (2012). "Anna's Hummingbird (Calypte anna)". The Birds of North America Online. In The Birds of North America (A. F. Poole, Editor), Cornell Lab of Ornithology, Ithaca, NY. doi:10.2173/bna.226.{{cite journal}}: CS1 maint: uses authors parameter (link)
  30. ^ "Official City Bird: Anna's Hummingbird". City of Vancouver. 2019. Retrieved 6 November 2019.
  31. ^ Gregory A Green (2 October 2018). "Anna's Hummingbird: Our winter hummingbird". BirdWatching. Retrieved 6 November 2019.

External links[edit]