Monday, May 30, 2016

Anna's Hummingbird

Having spent most of the past month in California it seems that the time is about right to resurrect this blog. It's been a few months since I felt that I had something to write about and I have been without inspiration since. Now I am back from the USA and I have shedloads of images, some of which are worth sharing. To start off I am posting a few images of Anna's Hummingbird, principally because this was one of the first birds that I saw in San Francisco; it was fairly easy to photograph, even with a compact camera, and it is a really photogenic animal.
Anna's Hummingbird - Calypte anna   Male - California April 2016
 This particular species is the commonest hummer in California and it seems to have little fear of humans being found frequently in urban areas including the centre of large cities, provided that there is suitable food and, presumably, breeding sites.
We saw tens of these birds in most places that we visited in central California, especially males. it now breeds from extreme north-western Mexico, north along the Pacific coast to south-western Canada. In the south it breeds as far east as Texas and its breeding range is expanding. It can be found year round in California.

Anna's Hummingbird - Calypte anna   Male - California April 2016
This bird is 10cm or 4" in length and the male is the only hummer in the USA with a rose-red throat and crown which is clear in the photographs above. However, you have to be viewing the bird at the correct angle. Move just a little bit, or the bird moves its head a little and the rose-red colour is replaced with anything from a dull orange through brown to black. As can be seen on the following three photos of the same bird taken seconds apart as it moved its head.

Male Anna's Hummingbird with dark brown throat and crown

...and the same bird in all of its rose-red splendour.
Here's the science: "The iridescent colours of the gorget are the result of the refraction of incident light caused by the microscopic structures of the feather barbules. The refraction works like a prism, splitting the light into rich, component colours. As the viewing angle changes, the refracted light becomes visible in a glowing, shimmering iridescent display." Further, "In the case of the vivid colours of the gorget, the prisms concentrate the colour so that it can be seen only from the front, as it would be seen by a territorial rival in a head-on confrontation."
And now...partially black and partially red.

The female is an altogether much drabber affair but they do sport a ruby-red central throat patch on  otherwise dingy grey-green underparts. The upperparts are a brighter green like the male.

Anna's Hummingbird - Calypte anna   Male posing for the camera  - California April 2016
 The only other species of Hummingbird that we managed to locate during our visit in April was Allen's Hummingbird. This species is much scarcer than Anna's although it is still fairly common in the right habitat. This bird winters in south central Mexico and journeys north to breed along much of the Pacific coast of the USA. There is a subspecies that colonised the Los Angeles area in the 1960s which has since spread north and south along the coast. This is non-migratory and the mild climate of California allows these birds to have up to four broods per year.

Allen's Hummingbird - Selasphorus sasin - Male California April 2016
This is the only shot that I managed to get of an Allen's. Perched on a wire way high. I may have to go back to try for a better shot next year!

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