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Back to basics -

The very fact that many species of birds migrate is common knowledge. In fact, it’s one of the first phenomena we learn about in biology class.

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Schooled -

As kids, we learn that every year flocks of birds move from their breeding (summer) homes to their nonbreeding (winter homes), in search of food and shelter.

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Did you know? -

It is less well known, perhaps, that as they move from A to B, many species of birds make pit stops along the way.

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Pit stoppin' -

During these pit stops, the birds tend to do whatever will prepare them best for the remainder of their journey.

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Dropping feathers - Often they molt (the process by which they shed and regrow some of their feathers), which is the equivalent of changing the tires on your car.

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Big city life -

Perhaps unexpectedly, many of the pit stops that birds make during their migration are in urban locations.

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Swainson's thrush -

According to one study by graduate student Ana Morales at McGill University, a species of bird called the Swainson’s thrush makes a surprisingly long pit stop in Montreal, for example.

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Piqued interest -

Scientists are very interested in why birds are attracted to cities. To quote Morales, “It’s pretty amazing that this small green area can support a bird for 40 days.”

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Leading theory -

According to Barbara Frei of Environment and Climate Change Canada, a department of the government of Canada, it may have a lot to do with light.

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Wealth of evidence -

Indeed, there is ample evidence dating back more than 100 years to suggest that birds are naturally drawn to sources of light.

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Proof -

One of the earliest recordings of this phenomenon was made by the turn of the century Irish anatomist and ornithologist Charles Patten.

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Sad truths -

Patten stationed himself at a lighthouse off the coast of Ireland, where he observed huge swarms of birds flying towards the lighthouse and, unfortunately, crashing into its windows.

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Some things don't change - Just as it did back then, this mesmerizing effect that light appears to have on birds can be very deadly.

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Gruesome end -

When Patten made his discovery, many of the birds he observed ended up dying as a result of their collision with the lighthouse.

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Statistics -

Nowadays, millions, perhaps even billions, of birds die every year as a result of crashing into lit-up buildings. Tall and particularly bright buildings are likely to cause the most deaths.

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Number crunch - For example, it is estimated that the McCormick Place convention center in Chicago was responsible for up to 11,567 avian deaths between 2000 and 2020.

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Double threat -

And brightly lit buildings are not the only threat faced by birds migrating to cities, either. Many also meet a bitter end when they cross the path of a domestic cat, for example.

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What does it all mean? -

The fact that cities are so treacherous to migratory birds has left scientists wondering what we can do to make them safer.

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The obvious solution -

The main suggestion made so far is to try and reduce the amount of light emitted in urban areas. Of course, much of the light in cities is unnecessary.

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Simple remedy -

According to Frank La Sorte at Cornell University, the simple act of turning off more lights at night could save the lives of thousands of birds.

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Some stats -

According to one study from 2021, switching off half the lights at McCormick Place in the spring and fall could reduce bird mortality by almost 60%.

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Security lights -

There are measures we can take at an individual level, too, to reduce the amount of light we emit, such as making sure our security lights point downwards.

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Cycle paths -

City councils may also consider introducing other measures, such as cycle paths that are lit by low-level lighting only.

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Can trees help? - There is also research to suggest that migratory birds fare better in cities that have adequate tree cover.

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Strong habitat -

Well-watered and mature trees can provide a habitat for hundreds of insect species, and are therefore great for birds that are insectivores.

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Looking good -

On this basis, it may be on city planners to ensure that cities have enough tree cover to accommodate any and all migrating birds, should they wish to enter the city.

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Caveat -

Of course, that is not to say that green spaces in cities should take the place of wetlands or dense forests when it comes to providing a habitat for certain bird species.

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It goes without saying -

Planting a few trees in an urban area should never be considered compensation for the destruction of natural bird habits.

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All in all -

That said, it does seem that birds are and will continue to be attracted to cities, and that there are things we can do to make our cities more accommodating to them.

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Food for thought -

So when you’re getting ready for bed tonight, remember to turn off your lights. You might just save the life of a bird!

Sources: (BBC) (All About Birds)

See also: Grounded! Flightless birds of the world

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