Wednesday May 22, 2013


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The swift movements of the rufous explained

Museum Musings

Every spring and summer, rufous hummingbirds come to Whistler, delighting locals and visitors with their antics and evading photographers who try to capture their tiny wings in action.

You may recognize them by their loud mating call which sounds like someone enthusiastically shouting, “do do do dooo”. The males of the species are notable for their bright red and sometimes brilliant orange colour. The females are greener in colour with some white markings.

These eight cm long birds are intrepid flyers, and spend their winters enjoying the warmer climate of Mexico. By body length, the rufous hummingbird has one of the longest migratory journeys of any bird. They are also known for their feisty and aggressive behaviour. Rufous hummingbirds have been known to take on larger birds and even chipmunks.

If you stop to watch a hummingbird hover in place, it may seem almost miraculous that it can maintain position in one place while vigorously pumping its wings. There are a number of different ways that birds can hover.

Hawks, for example, hold their wings still as they face wind, which keeps them in the air. Other birds, such as kestrels and kingfishers, flap their wings forcefully to keep themselves airborne.

Instead of relying solely on the downward power from their wings, hummingbirds rely partially on the upstroke from their wings to keep them aloft. Moths and other insects use a similar technique to hover; however, insects distribute their loft evenly between upward and downward strokes, while hummingbirds rely on the downward wing stroke for 75 per cent of their weight support.

Understanding that hummingbirds employ the upward stroke to stay aloft helps to explain why their wings are such a blur of motion. They rely on swift and continuous wing beating rather than powerful downward thrusts.

With all that wing beating, you can imagine how much a hummingbird must need to eat in order to maintain its weight (about that of a penny). A hummingbird can lose heat rapidly in cold weather and during the course of the night can lose as much as 10 per cent of its body weight. In order to maintain its weight, the hummingbird must slow down its metabolism and enter a state of torpor. This way it only loses one per cent of its bodyweight. During the day, hummingbirds recharge by feeding on nectar.

To help hummingbirds recharge, and to get a glimpse of them up close, a feeder with sugar and water is a good choice if you’re willing to clean it and change the water. If you don’t change the mixture and clean the feeder regularly, the sugar and water can become alcoholic and toxic to these little guys. If you don’t trust yourself to keep your feeder clean, there are a number of flowers that attract hummingbirds without requiring too much maintenance.

If you’re interested in learning more about Whistler’s birds, pop by the museum or get in touch with the Whistler Naturalists Society. Happy birding!

Robyn Goldsmith is the summer programs coordinator at the Whistler Museum.


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