Vagrant Birds: Why Some Migrating Birds Get Lost

Posted by Melissa Mayntz

Migration is an amazing seasonal spectacle when birders can expect to see tremendous flocks. Ducks, cranes, and swallows, soaring kettles of raptors, energetic warblers, tanagers, and buntings are all on the move.

The birds’ movements are predictable. Birds take highly traveled flyways and familiar routes to journey between their established breeding and non-breeding ranges. But what about unexpected sightings? What is going on when a roseate spoonbill appears in a wetland in Minnesota? Or a European robin visits a feeder in Pennsylvania? Or someone spots a vermilion flycatcher in a field in Maine?

How Birds Navigate in Migration

While we don’t fully understand all the details of bird migration, ornithologists do know that birds use different techniques to navigate on their long journeys. The exact navigation mechanisms vary with different species. Birds in different areas may use different techniques depending on how they migrate and how long their journey is. Typical bird navigation includes:

Astronomical Maps – Many birds use the position of the moon, sun, and stars to aid their migration, just as ancient sailors used the stars to plot their routes.
Magnetic Fields – Some birds have unique chemicals in their bills and parts of their brains that allow them to sense the earth’s magnetic field. It gives birds a superb internal compass.
Geographic Landmarks – Large landforms such as mountains, rivers, canyons, and coastlines offer visual clues to guide birds along the best migration routes.
Learned Routes – Some birds learn to migrate by following their parents along the route. This is especially true for many birds that migrate in large flocks.

Different Ways Birds Lose Their Way

Despite the different ways birds can navigate during migration, their methods are not foolproof. It is easy to get disoriented and stray far off track on such long journeys. Many different factors can interfere with birds’ successful migration, such as:

Weather – Strong storms can easily push birds far from their typical migration path. Hurricanes, strong front lines, or changing wind currents can all affect migrating birds.
Inexperience – Young birds that do not migrate with adults can easily become lost along the way as they try to puzzle out the mysteries of migration on their own.
Genetics – Birds that might have weaker internal compasses or dulled senses might have more trouble migrating than healthier, stronger individuals.
Hitchhiking – Some birds may inadvertently seek out shelter on moving ships to rest during migration, only to be taken far out of their way along the ship’s course.
Food – When birds follow food sources to refuel as they migrate, they could gradually get off track if those food sources are uneven and lead them astray.
Habitat Loss – Birds rely on proper shelter to rest during migration. If ongoing developments change the landscape or remove that habitat, it’s easy for birds to get lost.
Electronic Interference – Increasing amounts of electronic radiation from cell phones, wireless signals, and other sources might disorient birds and impact migration.
Light Pollution – In urban and suburban areas that are saturated with artificial light, birds might become disoriented because they cannot see the stars to navigate properly.

Seeing Vagrant Birds

With so many potential problems that could disrupt a bird’s migration, it is no surprise that different birds get lost and appear far from their natural ranges. These vagrant sightings can be very exciting for birders. They’re a great opportunity to see new and unusual bird species. Birders should pay attention to bird alert hotlines, social networking sites, blogs, and other news resources during peak migration periods to learn about vagrant birds. Be ready to take advantage of unusual sightings because the birds might move on at any time.

When there is a report of a vagrant bird, we should always keep the bird’s safety and well-being in mind. Even under the best circumstances, migration is a stressful, taxing endeavor. When a bird is lost, it can be even more uncertain and exhausted.

If the bird appears malnourished, weak, or injured in any way, contact a wildlife rehabilitator to evaluate the bird. Even if the bird appears healthy and energetic, birders should keep their distance to avoid stressing the bird.

At the same time, birders should also be aware of their surroundings and never trespass on private property, even for the best bird sighting or rarest vagrant. There will always be another migration to enjoy, and more birds to see. You never know which birds might get lost the next season!