Bird Migration

Bird Migration

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6:11 min.

Summary

Nature and climate change can be further explored with a recent analysis of the Breeding Bird Survey by Environment Canada that shows increased extreme weather under climate change could interfere with migration, forcing the birds off course.

Transcript of Video

Jay Ingram
But first, a long-held arrangement between birds and wind may be winding down. Global warming may be the one breaking that pact. Throughout the week we've been examining various effects of global warming and introducing you to the scientists who are trying to predict the outcome of the changing climate. Tonight on Earth Tones, how wind-assisted migration is being slowed down.

Reporter
Rob Butler scans the shores looking for little clues and little birds whose migratory path brings them to this beach each year.

Rob Butler
This is one of the key areas on the Pacific flyway for migrant shore birds. Hundreds of thousands will come here in the springtime, and there's only about a dozen of them on the entire Pacific Coast. This one here in Bounty Bay is one of the key ones in Canada.

Reporter
The birds come here to feed and refuel. The mud flats are saturated by water, and if you look closely, you'll see little worms, sometimes thousands in just a few cubic centimetres.

Rob Butler
These are tiny, tiny worms. They're just like popcorn actually to these shore birds. They eat thousands and thousands...

Reporter
Butler began his story after reports of declining song bird populations on the other side of North America. In the 1980s as the numbers of song birds along the east coast were dropping, scientists started to look for reasons. At first it was suggested it might be habitat loss, but Butler wanted to examine something else.

Rob Butler
We know that a fair number of these birds do this incredible journey. They leave North America from the New England states and the Maritimes, fly out across the Atlantic on tail winds, and then use the trade winds to draw them back to their wintering grounds in Central America and South America. So I had a look at this and I wanted to see whether the numbers of birds had declined in relation to the storms they encountered. As most of us probably know the hurricane season occurs in September and October in the Southern Atlantic right during the migration. So I had a look at this, and sure enough, as the numbers of storms went up, the numbers of song birds that we found on the breeding bird survey in North America went down.

Reporter
Butler believes more frequent storms during the last 20 years, knocked the birds off course and out of the air. They may have been getting lost at sea. To back up his theory, he analyzed computer models based on weather data collected since 1966.

Rob Butler
At about 30 or 35 knots.

Reporter
But there could be more problems ahead. Scientists predict a continuing increase in storms caused by global warming. The real question is, what will happen to the birds?

Rob Butler
Some of the meteorologists have been looking at this, and the feeling is that indeed those weather patterns might be tied to events like El Ninos. Whether that's anything to do with climate change is really the difficult question. And we need data over a long term to say this.

Reporter
For now Butler is shifting his focus closer to home, to Canada's west coast. He wants to know what will happen to shore birds because of climate change. Butler wants to find out just how important the winds are to bird migration and what will happen if the winds change.

Rob Butler
This is the critical piece of migration. When we added all the pieces up, without the wind our calculations indicate that the birds would run out of fuel. The wind gives them that little assistance and pushes them along and gets them to the next stopover site. What we think they're actually doing is using the wind as the... just like a surfer would use it.

Reporter
Now Butler is looking to see whether rising carbon dioxide levels, the culprit in global warming, may change wind direction and speed. Climatologist Bill Taylor took data from past years and projected what would happen to circulation patterns as more heat was trapped in the atmosphere.

Bill Taylor
What our wind data indicates is two things. It gives us an idea, a measurement of the speed and the direction of the wind. And depending on weather conditions, the wind typically is either out of the south or southwest or it's out of the northwest. Those are the two fairly common regimes that we see in the Gulf. So when we look at these, do an analysis of these winds, there are areas that are going to be, that will be more favourable to bird migration...

Reporter
The blue areas represent regions where wind direction could help push the birds along quickly, adding an extra one or two metres per second to their flying speed. The smaller orange area represents a headwind, which could slow them down.

Bill Taylor
As the winds shift, you know, it will affect the birds as well in how successful they are at migrating. The really interesting question will be whether the species can come through and survive this.

Reporter
How will the wind change affect the birds? That depends on the exact route they take and whether they can alter their traditional course. But while wind change may actually help some birds, climate change could still hurt migratory patterns in other ways. If temperatures climb or precipitation patterns change, ecosystems like this beach might be damaged. Rob Butler says the winds may be whispering a warning.

Rob Butler
We are a little bit concerned as if it was a canary in a coal mine. We have made the connection that for bird populations, water fowl populations, song bird populations, and perhaps even shore birds, that the success of their migration and how they do is related to weather changes. Now all we have to do is see whether the weather connection is due to climate change or if it's just the natural fluctuation in the earth's atmosphere.

Jay Ingram
Tonight's edition of Earth Tones was produced along with Environment Canada.