In flight – four billion birds moving through the seasons
WATERLOO REGION – Hummingbirds, eagles, turkey vultures, warblers, swans, geese, hawks, swallows… you name it, it’s probably on the move. Fall migration, the journey birds make from their northern breeding grounds to the warmer regions where they spend their winters, is underway.
Most birds that breed in Ontario don’t stay over the winter, says Ryan Norris, professor in the Department of Integrative Biology at the University of Guelph.
A large number of birds are on the move right now. The Cornell Lab of Ornithology estimates that four billion birds move to southern Canada and the United States each fall.
Some birds have extremely long migrations, such as the snow bobolink, which migrates about 20,000 kilometers from southern Ontario to southern South America.
In the world of birding, fall migration is considered more delicate than spring migration, as the usual telltale signs and signals on how to identify and locate birds associated with mating (such as song for the partners or the defense of the territory) have disappeared. They’re also harder to spot, as most birds replace their shiny breeding plumage with their typically much duller winter plumage, Norris explains.
But, if you can find them, there are more opportunities to see birds during the fall migration because there are more of them – the newly hatched generation migrates with their parents, and because the birds are not. in no hurry to mate and raise young, they take their time. Norris says some birds take up to twice as long to move south as they do north.
A common misconception is that birds learn to migrate from their parents, Norris says. While this may be true for some species that learn culturally from older generations, such as geese, many species are born simply with an innate map and compass system. This is reinforced by their own memories as they have some migrations under their belt.
“It’s quite difficult to understand how this young little bird, born in June, for example, is suddenly in September able to migrate to Brazil on its own, but they do,” says Norris.
In North America, there are four main routes birds take to cross the continent. These are the Pacific, Central, Mississippi and Atlantic flyways.
Birds follow their path on these migration routes by the sun, constellations or earth’s magnetic fields and combinations of these methods.
Most songbirds migrate at night, flying at altitudes of 1,000 or 1,500 feet, depending on cloud cover, Norris explains. This means that the billions of birds that migrate in the fall go undetected by predators and humans below.
But, “you can hear them,” says Norris. “On a beautiful, clear fall night where you don’t – you can’t do that in town because there’s too much white noise in the background – but if you’re outside, let’s say Algonquin Park or another park, or you can’t hear the traffic, you can hear the birds ‘chipping’ as they migrate.
“If you do it on a full moon night, and place your binoculars or a telescope against the full moon, and you are at the peak of the fall migration, you will see birds migrating. You will see them backlit by the moon.
By its nature, migration is difficult to study, says Norris, but an increase in the participation of citizens around the world through online birding applications like e-Bird as well as advancements in birding technology. tracking helps scientists better understand migration.
Over the past decade, an international network of automated telemetry towers has been established, starting with southern Ontario. These towers use a single radio frequency on the network to detect individuals with connected radio trackers, automatically keeping track of the movements of those individuals on the network.
This makes it possible to collect data on the movements of individuals without having to retrieve the device the following year. So if an individual is killed during migration, or if scientists cannot find them, their movements are still recorded.
Currently, a satellite system called Icarus, which stands for International Cooperation for Animal Research Using Space, is being developed to track the movements of small species from a satellite receiving station. Norris is eagerly awaiting the development of trackers compatible with Icarus and small enough for use on songbirds, or even smaller for insects.
“Maybe there will be a day when we can put a 0.1 gram transmitter on a butterfly and get information about its movements from here to Mexico via satellite. Maybe that day will come too. J ‘look forward to this. “