Saturday, November 15, 2008

Overwintering Anna's

Anna's Hummingbird, Calypte anna, male. Richmond BC, November 15, 2008.

Typically we in southern BC think of hummingbirds as harbingers of spring – and they are, but a different species, the Rufous Hummingbird, the rusty-coloured males of which arrive from Mexico in mid-March, as soon as the blossoms of salmonberry and currant are open. Over the next few months these birds frenetically court and breed and rear their young, and then in mid-to late-July begin the long trip south. By September, Rufous Hummingbirds should be sipping nectar in Cabo.

Rufous Hummingbird, Selasphorus rufus, male. Richmond BC, April 21, 2008.

Nature-lovers attuned to the life-history of this common species tend to take down their feeders in August. But not all those who feed birds pay attention to migration schedules, and thus, a few feeders stay up, a boon to any hummingbird lingering into fall. And as long as there is a critical mass of lingerers, kind souls keep feeding them. Many bird-lovers may not realize, or care, that by late August they are probably feeding not the familiar Rufous, but a second species that until relatively recently was not found here. Late-season hummingbird feeders, along with the presence of late-blooming suburban gardens, has given nature a bump, and allowed the Anna’s Hummingbird, historically a southern bird that might occasionally stray into British Columbia, to become a year-round feature of our fauna.

Anna's Hummingbird, Calypte anna, male. Richmond BC, November 15, 2008 (same bird as first picture, as are following birds).

The breeding range for Anna’s hummingbirds extends from southern California to (recently) southern Vancouver Island, where there is a handful of nesting records. After breeding, rather than following a strict migratory path, birds seem to disperse somewhat randomly, including northward, and then live where they can. Over the past few decades, these birds have become winter residents in increasingly hummingbird-friendly southern BC, and are notably common in parts of the relatively balmy, garden-rich Victoria region. I don’t know how common Anna’s Hummingbirds are in Richmond. One visited my feeder last fall for a week or so.

How Anna’s Hummingbirds fit into the evolving local ecosystem is not clear, because we don’t know what exactly these newcomers are doing here, and can’t predict if a significant breeding population will develop. We also don’t know with certainty to what extent urban nature-lovers have contributed to the expansion of this species’ range, which may also have been encouraged by the relatively mild winters of recent years. What I find interesting is the indirect role the original hummingbird species, the summer-resident Rufous, may have had in the range expansion of the Anna’s. We plant exotics such as Fuchsia, and put up feeders for the birds of spring, which inadvertently create resources for a second species that happens by, California beach bums who hang out as long as the living is easy.

We tend to forget that we are part of nature, that it goes on around us and that we add to and detract from it in uncountable ways. We tweak it, often without knowing, and in this case perhaps are enabling a species to expand its range. If so, I’m not sure that’s a good thing, but it’s an interesting thing.


Zoƫ said...

How wonderful to see them in your own garden, nothing here compares.

Ralph D. Keir said...

From Mill Bay 19 Dec 2008 had one for over a week now, despite the frigid temp. Hungry little devils and a joy to watch.