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Wednesday, January 15, 2014

Can You Tell an Anna's from a Rufous?

by Sharon McInnes

We have a pair of Anna’s hummingbirds in the yard this winter. If you, too, have hummers right now, here on Gabriola Island, they’re also Anna’s, the beauties that Cornell’s All About Birds site describes as “more like flying jewelry than birds”. 

Male Anna's. Photo by Alan Vernon.
CC license. 

Anna’s have been over-wintering in BC only for the past twenty years or so. Before that they lived exclusively in California and the Baja. But starting in the 1930’s, they began expanding their range northward, probably as a result of more and more backyard feeders as well as the growing popularity of exotic trees, such as eucalyptus, that provided both nectar and nest sites. Some birders worry that feeding Anna’s will interfere with migration. Here’s what the Rocky Point Bird Observatory scientists say on the subject: 

Do not worry! Feeders will not stop a bird migrating, a process that is triggered by the bird's internal clock and levels of sunshine. Anna's are with us year round and their presence at feeders has just become more obvious because their numbers are increasing locally.” (http://rpbo.org/hummingbirds.php)

In the spring and summer, we have both Anna’s (Calypte anna) and Rufous hummingbirds (Selasphorus rufus) on Gabriola. You can tell them apart by their colouring. The sure-fire give-away is that the Anna’s has no rufous (orangey-brown) plumage anywhere, and has little white spots around the eyes. Once you know you’re looking at an Anna’s, you can readily distinguish male from female: the male’s red gorget, or throat patch, extends right over his head, making him a sparkling redhead when the sun shines on his iridescent hood. Striking emerald green plumage covers his back and bleeds onto his sides and white belly. The female, not as showy, is mostly emerald green and grey in colour with a small iridescent red gorget on the throat.

Male Rufous hummers - note the bright red iridescent gorget
and the rufous (brownish) plumage

The female Rufous hummer has a little rufous colouring
on its sides but no shining red throat patch

The female Anna's has no rufous colouring anywhere.  

Does size matter?
It does if you're a hummingbird facing down a House Finch! 

In the spring, the male Anna’s performs a wild and wonderful courtship display.  From as high as forty metres, he does a nearly vertical dive downward, all the while eyeing the female. (On sunny days, he orients his body to take advantage of the sun reflecting on his iridescent throat and crown.) As he comes to a stop, he emits a short high-pitched explosive squeak (more on this later) then “chases” her (she has, by now, indicated her interest, somehow) while she leads him to her nest site. (Wiley little thing.) The female then perches and settles in to watch the show while the male does his “shuttle display”, swinging back and forth about half a metre above her, singing like crazy. All this lasts only about twelve seconds, does the trick, apparently. 

More now about that high-pitched squeak: until 2008 the source of this sound was a mystery. Then student researchers at the University of California used ultra-high-speed video cameras to film Anna’s in action, and discovered the squeak was made not by the hummer’s throat but by his tail feathers. (More here). In cold weather, though, all that matters to a hummer is staying alive. 

This Rufous hummer got caught
in a surprise snowfall one spring

Not all do, of course.  But if you have a feeder up, there are things you can do to help. Most importantly, keep the nectar from freezing. (What’s more heartbreaking than seeing an Anna’s sitting on the perch of a feeder with frozen nectar inside?) Some people (me included) have two or three feeders they rotate as needed, one in the house, staying warm, one outside, getting cold. When the outside feeder gets very cold (or freezes overnight) bring it in and replace it with the other one. Some people keep their feeders from freezing by placing homemade warmers, often concocted from light bulbs, just under the feeder. (I’d like to use my birdbath heater to keep the nectar from freezing but haven’t figured out how to do that yet.) Others wrap feeders in pipe insulation or beer mug insulators or even woolen socks. Many people use a sweeter than usual solution (3 sugar to 1 water) in winter because it doesn’t freeze as quickly as the 4-1 solution. Whatever you do to keep the nectar from freezing, be sure to place your feeders a good distance apart so that the hummer has to fly (thereby creating body heat) to get to them. 

A version of this article was first published in The Flying Shingle on January 13 2014. 

2 comments:

Barbara said...

Hi I noticed a Hummingbird outside my window in the peach tree and so I have now hung up a feeder for her. I say "her"
because she isn't very colourful. But seems paler on the breast. It's hard to tell because she stays out of view when possible. I also think she seems quite large. I'm guessing that I'll have her for the winter so I'm going to maintain the feeder which is being drunk rather quickly.

The Island Book Shoppe said...

It sounds like you have an Anna's, Barbara. If you live on Gabriola, or even in BC, all the Rufous have returned to their wintering grounds, probably in Mexico or Central America.