This hummingbird is one of two species of hummingbird
that belongs to the genus Calypte,
the other is the Costa's hummingbird (Calypte
costae). Both species look similar to each, but male Anna’s hummingbird is
characterized by their gorget (patch of coloured feathers on the throat) which
is a crimson/magenta colour while Costa's hummingbird gorget is a purple colour
(National Geographic, 2006). Females are less brightly coloured than the males,
although both have bronze-green feathers on their back, pale grey chest/belly
and green flanks (Giraldo et al, 2018). Their current geographic range includes
Canada, Mexico and the United States and prefer tropical/subtropical forest for
their habitat (BirdLife International, 2016).
Male
(right) by Robert McMorran and female (female) by Matthew Field.
Unlike
most species of hummingbirds that perform courtship dances to impress females,
the male Anna’s hummingbird performs sings (Stiles, 1982) to impress the female
that enters his territory. If she doesn’t leave, he will perform a display
dives at high speed over the female making dive sounds (Clark and Feo, 2010).
Below are two videos of Anna’s hummingbird, one is by Timothy Barksdale of
birds feeding and perching on a feeder and the other is an Anna’s hummingbird
perch and singing by Larry Arbanas.
The biggest threat to this species of hummingbird are diseases introduced to their environment. The most common disease that affect the Anna’s hummingbird is the avian pox virus. Avian pox virus is transferred by mosquitoes, contaminated surfaces and airborne particles. Birds affected with this virus gain wart like growths around areas free of feathers or can characterized as raised, yellow blemishes around the mouth, lungs, trachea and esophagus. This can lead to blindness, decreased egg production, poor growth, reduced male mating success and death (Godoy et al, 2014).
Next time, we will be covering a newt that spends most of
its life on dry land.
References
BirdLife International 2016. Calypte anna. The IUCN Red
List of Threatened Species 2016: e.T22688199A93186783.
Clark, C.J. & Feo, T.J. 2010, "Why Do Calypte
Hummingbirds "Sing" with Both Their Tail and Their Syrinx? An
Apparent Example of Sexual Sensory Bias", American Naturalist, vol. 175,
no. 1, pp. 27-37.
Giraldo, M., Parra, J. & Stavenga, D. 2018,
"Iridescent colouration of male Anna's hummingbird (Calypte anna) caused
by multilayered barbules", JOURNAL OF COMPARATIVE PHYSIOLOGY
A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY, vol. 204, no. 12, pp.
965-975.
Godoy, L.A., Tell, L.A. & Ernest, H.B. 2014,
"Hummingbird health: pathogens and disease conditions in the family
Trochilidae", Journal of Ornithology, vol. 155, no. 1, pp. 1-12.
National Geographic book, Complete Birds of North
America, 2006
Stiles, F.G. 1982, "Aggressive and Courtship
Displays of the Male Anna's Hummingbird", The Condor, vol. 84, no. 2, pp.
208-225.
Picture and video references
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