The Basics of Bird Migration: What, Why, and Where?

The classic image of migration is geese flying south in V-shaped flocks, which are a result of the annual large-scale movement between their breeding (summer), and non-breeding (winter). Geese are not the only migratory bird. More than half of the more than 600 North American breeding birds are migratory.

Why do birds migrate?

Birds migrate to find higher or more abundant resources. Food and nesting sites are the two main resources that birds seek.

Birds who nest in the Northern Hemisphere migrate northward in spring in order to take advantage of growing insect populations, budding plants, and a variety of nesting sites. The birds migrate south as winter draws nearer and there is less food available. Although it is tempting to flee the cold, many species, including hummingbirds can survive freezing temperatures provided there is enough food.

Types of Migration

Migration is a term that refers to the movement of large numbers of animals on a regular basis. You can look at migration by looking at the distances covered.

Permanent residents are not allowed to migrate. They can find sufficient food all year.

The short-distance migrants travel only a small distance. They move from one mountainside to another.

Medium-distance migrants travel from one state to another.

Long-distance migrants move often from their breeding areas in the United States or Canada to their wintering grounds in Central or South America. Long-distance migration is an important feature of about 350 North American bird species, despite the long journeys involved.

While the pattern of migration may vary between each group, it is most common for short- and medium-distance migrants.

Origins of Long-Distance Migration

Although short-distance movement is likely to have originated from a simple need for food, long-distance migration patterns are more complicated. They have evolved over thousands of year and are at least partly controlled by the birds' genetic makeup. They incorporate the responses to weather, geography and food sources as well as day length.

It seems odd to think of birds who spend their winters in the tropics leaving their home and heading north. It seems strange to imagine making such a long, difficult trip north in spring. One theory is that these birds' tropical ancestors dispersed northward over many generations. They were able to raise 4-6 children per year due to the greater availability of insects and longer days than their relatives who live at home (2-3). The birds returned to their tropical habitats as winter weather and decreasing food supply made it more difficult for them to move north from their breeding areas. This theory is supported by the fact that the majority of North American vireos and flycatchers, warblers/warblers, orioles, swallows, and tanagers are tropic-adapted.

What triggers migration?

There are many mechanisms that can trigger migratory behavior. They are often not fully understood. Changes in day length, temperature, food supply, genetic predisposition, and genetic predisposition can all trigger migration. People who have kept cage birds for centuries have observed that migratory species have a period when they are restless, fluttering towards one side of the cage. German behavioral scientists called this behavior zugunruhe, which means migratory restlessness. Different species of birds, or even different segments of the same population, may have different migratory patterns.

How do birds navigate?

Migration birds often travel thousands of miles each year, and can travel the same route year after year. Many first-year birds make their first migration by themselves. They often find their winter home, even though they have never seen it before, and they return to the same place each spring.

Because birds use multiple senses to navigate, it is difficult to understand the secrets behind their navigational abilities. Birds can use the magnetic field of the earth to sense the earth's magnetic fields and the sun to get information about their compass. Information is also derived from landmarks and the position of the sun setting. Evidence suggests that homing pigeons are aided by their sense of smell.

Certain species, such as waterfowls and cranes, have preferred routes for their annual migrations. These preferred pathways often link to crucial stopover areas that provide food supplies essential to birds' survival. The migration patterns of smaller birds are more common in the countryside. Recent eBird data studies have shown that small birds migrate in broad fronts across the landscape in order to benefit from seasonal patterns in weather, food, and weather.

Migration Risks

It is dangerous and exhausting to travel a distance of more than a thousand miles round trip. This is a difficult task that puts both birds' mental and physical capabilities to the test. The dangers of the journey include the physical stress, inadequate food supplies, bad weather and greater exposure to predators.

Long-distant migrants have faced a growing threat from tall buildings and communication towers in recent years. Millions of people are killed every year by the light from tall buildings each year. This problem is being addressed by the Fatal Light Awareness Program in Toronto, Ontario.

Migration Studies

Researchers use a variety of techniques to study migration. These include satellite tracking and banding. A relatively new technique that uses lightweight devices called geolocators is also used. The goal is to find important wintering and stopover locations. These key locations can then be protected and saved once they are identified.

The Central Platte River Valley, Nebraska, is used by approximately 500,000 Sandhill Cranes, as well as some endangered Whooping Cranes, to stage their migration northwards to Canada, Alaska, and Siberian Arctic.

What is a Migrant Trap?

Some areas seem to be able to attract migrating birds in greater numbers than usual. These "migrant traps", often known as birding hotspots, are well-known. This is usually due to local weather conditions, a surplus of food, or the topography of the area.

Small songbirds, for example, that migrate north in spring fly directly over Gulf of Mexico and land on the coasts of the Gulf Coast States. These birds can become exhausted if they land in the face of headwinds and storms. They will seek shelter and food at the closest location, which is usually live oak groves on barrier island. These traps are very popular among birders and have earned an international reputation.

The peninsulas are also a great place to concentrate migrating birds. They follow the land, then stop and wait before they launch over water. It is why Point Pelee in Ontario, Point Reyes in California, Point Pelee in New Jersey and Cape May, New Jersey have great reputations for being migration hotspots.

People who feed birds in their yard can attract species that they don't normally see. Spring migration is a great time to do this. A backyard can be attractive to migrating songbirds by providing food, water, and natural food sources.

Range maps

To determine when and if a species is present, it's a good idea for field guides to include range maps. When working with migratory birds, range maps can be especially helpful. They can be confusing as the ranges of birds may change from year to year, just as they do for migratory species like redpolls. Some species' ranges can change quite rapidly. These changes may occur in shorter time periods than the field guide's republication time. This is best illustrated by the Eurasian Collared-Dove.

Digital versions of range maps that are data-driven and digitally generated are starting to address these limitations. These maps were made possible by hundreds of millions of eBird observation submitted by birdwatchers all over the globe. Scientists can now create animated maps showing the ebb and flow of a species across a continent over a year using "Big Data". This allows them to understand larger patterns of movement as well as produce animated maps.

Additional Resources

Migration is fascinating and there are many things to be learned. Songbird Journeys by Miyoko Chu from Cornell Lab explores many aspects related to migration in an engaging and easy-to-read format. You can find more information about the incredible phenomenon of bird migration in the Cornell Lab's Handbook of Bird Biology.

Bird migration is the normal seasonal traveling, usually north and south along an migrate route, between wintering and breeding grounds. Many species of birds regularly migrate. Migrants are those that leave their offspring behind for long periods to seek food or avoid predators. Migrants also tend to be larger and heavier than non-migrants, with short wings and long bodies.

Most species of birds migrate for several reasons. To establish which birds migrate, it's necessary to understand why they do so and how they do so. Migrating is a complex process that involves a number of factors that can vary from species to species, but all involve the need to survive and advance to the next habitat to start reproduction.

Birds have evolved over thousands of years to be able to move from one place to another quickly and easily. They have the equipment needed for successful migration, which includes wings that can rapidly increase in length in order to gain increased speed, as well as thick flaps of air along their bodies that provide increased buoyancy. They are also naturally strong and durable. During the summer months when they are not migrating, they spend most of their time basking on the branches of trees, or in water. During the fall migration season, which is generally between September and May, migratory birds rest at a greater distance from the ground and concentrate their energy on building up their strength and durability for their return flight.

During the fall migration, wikelski (or "wigeon-owls") are the most common birds to see during this time. A common song in the fall migration is called "Wikelski", which was composed by the Canadian black woodpecker. The wikelski is a high-pitched wail that mainly sings for about two minutes, but the sound will reach as far as thirty miles away. This makes it one of the most long-lasting songs of all bird species. Other common wikelski include the chirp, which is a kind of chirping that goes much longer than a chirp; and the flute, which is a low-pitched wail. All other wikelski are only used as background notes to the main song.

Throughout the summer season, several varieties of birds which birds commonly migrate, such as the chickadees, will appear in parks and mixed-aged populations. In most cases these birds are not wikelski. They may, however, be wader birds and/or mid-air predators. Common birds that birds frequently migrate include white storks, red-winged blackbirds, northern star anaconda, purple Martin, white-crowned sparrow, white-crowned hummingbird, green-winged teal, little blue book, house finch, little owl, red-faced gull, white-rumped sparrow, white-crowned conure, house finch, purple-winged albion, black-crowned bells, and many others. While these birds are seen regularly migrating, a good birder will notice the birds' migration patterns at least once in his lifetime.

Knowing which birds migrate and why can be helpful in determining which species will be seen during a bird-watching trip. Familiar species will often be present during spring migration seasons, so the birder should look out for these species during his or her next trip. Also, migrating birds often lay eggs, so new hatchlings should also be on the list. The timing of when a species migrates can vary from season to season. However, most birds prefer to arrive during the winter to avoid the heat of summer and head back to their winter destinations.

A good birder who wants to know which birds migrate can also help other birders in their quest for the mystery birds. Birding forums and websites offer a great place to get answers to questions that birder have. Many enthusiasts offer tips and hints on what the best times to see a particular species might be. While some areas offer certain months as prime migrating times, other areas are known for the less predictable behavior of migratory birds. These sites and forums give the birder a resource for knowledge and enjoyment as he studies which birds migrate through the seasons.

Those who study the seasons can use this information to plan trips that include visits by a specific species. For instance, in early May we often see goldfinches and other small birds migrate from Canada and the northern United States to nesting locations in Mexico. Early spring is also a good time for Atlantic White-sided birds. The spring and fall seasons are known for the abundance of some migratory birds. As soon as the leaves start to change colors from green to orange, birds begin to prepare for a long migration journey ahead. Knowing which birds migrate can help a birder plan an exciting vacation or just go to a park and enjoy the beauty of nature.