Anna’s Hummingbird – the year round hummer
Hummingbirds are surely one of the birds humans love best. They zip around from flower to flower, are beautifully coloured, visit our nectar feeders readily and have attitude. In spite of their small size they make themselves known. The America’s are the only home to hummingbirds. South America is particularly rich in hummingbird species. The ecological niche that hummingbirds fill here is filled by other birds and insects on the other continents.
The flight of the hummingbird is perhaps what sets it apart most readily from other birds. No other bird can fly backwards, hover or rise straight up. The ball and socket shoulder joint can rotate 180 degrees. In regular flight the wings beat 70 times per second – though beat is perhaps not the best descriptor, since the wing beat is actually a rotation. The pattern is oval in regular flight and a figure eight when hovering. Because of this motion, unlike other birds, when a hummingbird flies its body stays mostly upright. They fly at speeds around 40 to 50 km/hour. Diving speeds are close to 100 km/hour. When diving the wings beat at around 200 times per second!
Vancouver Island has two species of hummingbirds – the Rufous and the Anna’s. The Rufous hummingbird is identified by its smaller, slimmer build and an orange throat. The male Rufous is brilliant orange while the females are green and orange. Around here it is a summer resident and has a long history of occupation. The Anna’s hummingbird is larger than the Rufous and the male has an iridescent rosy crown and throat, which it displays. The traditional range of the Anna’s hummingbird is the northern Baja area to southern California. It is a rather recent immigrant to our area but has taken up permanent residency and its population is increasing rapidly. Some factors in this range expansion might include warmer winters, the planting of exotic flowering trees and shrubs, nectar feeders and the fact that the Anna’s is not a migratory species. As the population builds, birds move into new territories and so the range expands. Rufous hummingbirds by contrast migrate to survive winter. This means they need to re-establish territories. Also, it reduces the length of the breeding season. Anna’s hummingbirds in our area can nest up to four times in a year.
The nests, about an inch high and an inch and a half wide, are made of cattail or thistle down, small leaves or feathers and bound together with spider web silk. The outside is adorned with mosses and lichens. The nests typically contain 2 eggs, each a half inch long. The female incubates the eggs for 16 days and then tends to the hatchlings for another 20 days or so, feeding the young a pre-digested diet (a more palatable description evades me) of small insects such as midges and nectar. Around here nesting typically takes place between January and July.
Other than when feeding at flowers or at nectar feeders the most prominent visual displays are the males dive displays to attract mates. He hovers in front of the object of his desires (not always a hummingbird) then climbs over 100 feet, then dives and ends in a steep arc back at the point where he started. The rapid flaring of the tail acts as a brake and the spreading of the ten tail feathers also creates a resonance similar to its vocalizations, but considerably louder. The mechanics of this sound production is similar to the vibration of a reed instrument. Non-vocal displays are not common among birds but are employed by some species, for example by grouse drumming. Hummingbirds in general do use this technique. In addition the Anna’s have complex and learned songs, which are not common to the group of birds to which hummingbirds belong.
The small size of the hummingbird creates some challenges for surviving cold temperatures or even nights. It does this by dropping its body temperature from 105 degrees Fahrenheit to 48 degrees Fahrenheit and also dropping its heart rate and breathing rate to enter a mini-hibernation state called torpor. Recovering from torpor can take up to an hour and as soon as they are up and about they need to recover the energy reserves lost overnight. The small size of hummingbirds is also thought to play a role in the reduction of some organs – the bladder, a gall bladder, and a penis in males (not usual for birds to not have a penis) and a right ovary in females. This reduction in organs reduces weight and thus makes flight more efficient and also reduces the energy that a bird must ingest.
The easiest place to observe Anna’s hummingbirds is at a nectar feeder, but also keep an eye out at brightly coloured flowers (I’ve had them frequent my red handled pruning secateurs). In the spring males are frequently perched on the top branches of trees and shrubs and sing. Also, look and listen to their display flights – a harbinger at this time of year of spring.
Reference: Ian Cruickshank, Allaboutbirds.com
Jay Rastogi is a naturalist, hoticulturalist and educator living in Yellow Point. Reach him at ecoforestry [at] gmail [dot] com