About DUC

The Migration Station

Billions of birds migrate during the course of a year. How do they do it?

Specialization in Navigation

It is widely believed there are four methods birds use to migrate from northern breeding areas to southern wintering grounds. The sun, stars, Earth's magnetic field and visual landmarks all help to guide birds back to the same spots year after year.

Birds are aware of the light and dark cycles that occur during the day. They also rely on shadows to help them determine direction. These two elements combined allow birds to use the sun as a compass.
Birds orient themselves according to the position of the stars that help to distinguish north from south. Problems arise when the sky clouds over at night. Bright city lights easily disorient migrating birds, especially songbirds.
Scientists have detected small crystals of magnetic iron oxide within the base of birds' beaks and bills. A commonly held theory is that these crystals help the birds respond to the Earth's magnetic fields. While the magnetic poles and geographic poles do differ, it is believed that magnetic fields are just another tool in a bird's migration navigation kit.
To those who have observed migrations, it is apparent that the birds follow rivers, coastlines, ridges and mountains. The type of landmarks used likely vary depending on the altitude of flight.

By Sun or by Moon?

The birds that migrate primarily during the day are: larger birds like ducks, geese, swans, cormorants, herons and cranes; fast birds like terns; or birds of prey that rely on upswelling air currents that result from the Earth's heating during the day.

Many songbirds and poor flying birds, such as coots or grebes, rarely fly during the day because raptors, such as the peregrine falcon, pose such a strong threat to their survival. On clear autumn nights, you can experience midnight migrations by watching flocks travel across the moon.

Capt-hens!

Migrating birds and jet aircraft both take advantage of high altitudes to increase performance. During migration, some birds have been detected travelling at 1.5 to six kilometres (5,000 to 20,000 feet). This is well above normal flying heights. Efficiency is increased at high altitudes, but so is exposure to predators. This may further explain why smaller birds migrate at night.

Mom? Is that your foot in my face?

Geese and swans, both of which experience long-term pair bonds of several years, migrate north and south in family groups. Snow geese, white-fronted geese and most varieties of Canada geese remain in family groups throughout the winter. But in brant and cackling Canada geese, young become independent of their parents during their first winter. In ducks, the family grouping of hens plus young breaks up long before migration ever starts.