0 anna's hummingbird (calypte anna), a medium-sized hummingbird native to the west coast of north america , was named after anna massna , duchess of rivoli .
1  in the early 20th century , anna's hummingbird bred only in northern baja california and southern california .
2  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 more extensively expand its breeding range .
3 anna's hummingbird is 3.9 to 4.3 in (9.9 to 10.9 cm) long .
4  it has an iridescent bronze-green back , a pale grey chest and belly , and green flanks .
5  its bill is long , straight and slender .
6  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 .
7  female anna's hummingbirds also have iridescent red gorgets , though they are usually smaller and less brilliant than the males' .
8  anna's is the only north american hummingbird species with a red crown .
9  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 .
10 these birds feed on nectar from flowers using a long extendable tongue .
11  they also consume small insects and other arthropods caught in flight or gleaned from vegetation .
12  a pbs documentary shows how anna's hummingbirds eat flying insects .
13  they aim for the flying insect , then open their beaks to capture the prey .
14 while collecting nectar , they also assist in plant pollination .
15  this species sometimes consumes tree sap .
16  the male's call is scratchy metallic , and it perches above head-level in trees and shrubs .
17  they are frequently seen in backyards and parks , and commonly found at feeders and flowering plants .
18 anna's hummingbirds can shake their bodies 55 times per second to shed rain while in flight .
19  when done in dry weather , shaking may remove pollen or dirt from feathers .
20 open-wooded or shrubby areas and mountain meadows along the pacific coast from british columbia to arizona make up c .
21  anna's breeding habitat .
22  the female raises the young without the assistance of the male .
23  the female bird builds a large nest in a shrub or tree , or in vines or on wires .
24  the round , {convert|3.8|to|5.1|cm|in|adj=on} diameter nest is built of very small twigs , lichen and other mosses , and often lined with downy feathers or animal hair .
25  the nest materials are bound together with spider silk or other sticky materials .
26  they are known to nest early as mid-december and as late as june .
27 unlike most hummingbirds , the male anna's hummingbird sings during courtship .
28  the song is thin and squeaky .
29  during the breeding season , males can be observed performing a remarkable display , called a display dive , on their territories .
30  when a female flies onto a male's territory , he rises up approximately {convert|30|m|ft} before diving over the recipient .
31  as he approaches the bottom of the dive the males reach an average speed of 27 m/s , which is 385 body lengths per second .
32   at the bottom of the dive the male travels {convert|23|m/s|mph}, and produces a loud sound described by some as an "explosive squeak" with their outer tail-feathers .
33 anna's hummingbirds will sometimes hybridize with other species , but this is not very common .
34  these natural hybrids have been mistaken for new species .
35  a bird , allegedly collected in bolaos , mexico , was described and named selasphorus floresii (gould , 1861), or floresi's hummingbird .
36  several more specimens were collected in california over a long period , and the species was considered extremely rare .
37  it was later determined that the specimens were the hybrid offspring of an anna's hummingbird and an allen's hummingbird .
38  a single bird collected in santa barbara , california , was described and named trochilus violajugulum (jeffries , 1888), or violet-throated hummingbird .
39  it was later determined to be a hybrid between an anna's hummingbird and a black-chinned hummingbird .
40 anna's hummingbirds are found along the western coast of north america , from southern canada to northern baja california , and inland to southern arizona .
41  they tend to be permanent residents within their range , and are very territorial .
42  however , birds have been spotted far outside their range in such places as southern alaska , saskatchewan , new york , florida , louisiana and newfoundland .
43 anna's hummingbirds are the only hummingbirds to spend the winter in northern climates; they are able to do this as there are enough winter flowers and food to support them .
44  during cold temperatures , anna's hummingbirds gradually gain weight during the day as they convert sugar to fat .
45  in addition , hummingbirds with inadequate stores of body fat or insufficient plumage are able to survive periods of sub-freezing weather by lowering their metabolic rate and entering a state of torpor .
46 there are an estimated 1.5 million anna's hummingbirds .
47  their population appears to be stable , and they are not considered an endangered species .
