Migratory patterns vary by species and sometimes within the same species. Almost any possible pattern is possible and can be seen in one or more species.
Some species do not migrate. They are able to find adequate supplies of food throughout the winter. The Northern Cardinal and Northwestern Crow fall into this category.
Short distance migrants
Adding to the diversity of migration patterns are birds that migrate short distances. This often includes species that are permanent residents in most of their range, but with migratory tendencies on the edges or in pockets of their range.
Populations are typically sedentary, year-round residents. However, in the Smoky Mountains of the southeast United States seasonal movements between low-elevation wintering and high-elevation breeding habitats have been observed.
Hairy Woodpeckers are primarily nonmigratory. They are permanent residents throughout their breeding range. However, northernmost populations display irregular and unpredictable wandering in winter. Local post-nesting short-distance movements take place in some areas. In some situations individuals breeding at higher altitudes seem to disperse to lower altitudes during nonbreeding season or from inland to coastal locations.
Generally non-migratory except for some movements to lower elevations. In Arizona, many individuals move to riparian communities in late September and return to higher elevations in early April.
The Blue Grouse of the Northern Rockies reverses the pattern of moving to lower altitudes in the winter. These birds move higher in the mountains in the winter to feed on conifer needles, then back down to the valleys in the spring where a wider variety of food sources exist for feeding their young.
Medium distance migrants
The ranges of some species may cover large parts of the United States and Canada. Medium distance migrants tend to exhibit a variety of irregular patterns of north/south migration but remain in North America.
Blue Jays really mix it up. Blue Jay migration is an obvious phenomenon in some areas, with thousands moving past certain points along the East Coast each fall. Much remains a mystery, however. Some jays are present throughout the winter in all parts of the range. No one knows for sure which Blue Jays move and which stay put, or why. Although young jays may be more likely to migrate than adults, many adults do migrate. Some individual jays may migrate south in one year, stay north the next winter, and then migrate south again the next year. Many people who feed birds in their backyard may be seeing one population of Blue Jays in the winter and an entirely different population of jays in the summer.
Eastern Bluebirds (and several other species) have a flexible approach to migration. They may move only as far south as is needed for food and shelter and may move further south if local conditions become less conducive to their survival.
This migration pattern is not consistent with all Eastern Bluebird populations. In the southern part of their range the Eastern Bluebird is a permanent resident.
Several subspecies of the White-crowned Sparrow have been studied. The northernmost breeding population migrates from Alaska and the Yukon to the southern plains of the United States and into northern Mexico. A different subspecies breeds farther south, ranging from British Columbia to northern California. These white-crowns migrate a shorter distance to the lowlands of central and southern California. Finally, a third subspecies is a permanent resident in parts of coastal California.
Killdeers are classified as medium-distance partial migrants, another way of saying their movements are complex and poorly understood. Banding records suggest general southward fall migration in North American birds, with no strong directional orientation. Birds from northern areas in eastern North America winter in gulf-coast and south Atlantic states. Some Killdeers migrate through western North America and Central America while others winter in the coastal and wetland areas of California.
Long distance migrants
Many species undertake migratory journeys that can take weeks to complete and cover thousands of miles.
Approximately 350 species fall into the Neotropic migrant category. These birds breed in the United States and Canada. They winter in the Caribbean, Mexico, Central America and South America. Neotropical migrants include raptors, vultures, waterfowl, shorebirds, and passerine species such as hummingbirds, thrushes, warblers, orioles, and tanagers.
The term neotropical comes from "neo" referring to new and the new world, e.g. the Americas. Tropical is defined as the latitudinal region between the Tropic of Cancer and the Tropic of Capricorn.
Other long-distant migrants
Each fall Whooping Cranes that nest in Wood Buffalo National Park in Saskatchewan undertake a 2,500 mile flight south to the Aransas National Wildlife Refuge in Texas. By gliding on wind currents, they can stay aloft for 10 hours and cover up to 450 miles. The trip takes anywhere from eight to 30 days and the cranes arrive on the wintering grounds between late October and mid-December.
The champion of long distance migration is the Arctic Tern. Arctic Terns can travel as much as 24,000 miles (round trip) each year from their breeding grounds in far northern Canada to their winter home in Antarctica. The terns follow two major pathways on their trips back and forth to the poles.
Terns that breed near Alaska and Canada migrate down the western coast of North, Central and South America. Birds from Greenland and Siberia take a route along the western coasts of Europe and Africa. Some birds in this group splinter off at the Horn of Africa and cross the Atlantic. They then fly down the east coast of South America. After spending only about two months in Antarctica they start their northward journey. The Arctic Tern can live to be at least 34 years old, in which case it may have flown more than 800,000 miles in its lifetime!