REGULAR AND RARE
Nearly 1,000 species of birds can be found in North America. About 700 of these breed or visit on a regular basis, and another 300 or so species are rare accidentals, strays, and other less commonly seen birds. Bird populations vary by species, and bird populations and their distributions change over time. Every bird that we see today reflects only a moment in that species' evolutionary history on Earth.
Is the Greater Shearwater regular or rare?
In Atlantic waters the Greater Shearwater (right) is regularly seen, but on the Pacific coast the rare bird alert would go into effect if this bird showed up.
Does regular mean abundant?
Not all regular birds are common. The abundant House Sparrow is a regular resident of North America. By contrast, the Red-cockaded Woodpecker (left) is a regular resident whose numbers have so declined that it is listed as an endangered bird.
What will be gone tomorrow?
Who knows which birds will disappear, like the once numerous but now extinct Passenger Pigeon (right)? Bird populations and their distributions evolve naturally over time. In addition, birds are so threatened today by human causes that the future of many bird species is uncertain.
Because of its proximity to the Asian mainland, Alaska has numerous species appearing as strays from Asia, typically seen at migratory periods or after violent storms when birds can be blown off course. The Siberian Rubythroat (right) is one such species.
Western strays originate both from the tropics and Asia, typically during migratory periods. The brambling (left) strays into our region from Asia.
Most Southwestern strays, like the Aztec Thrush (right), originate from Mexico. Although migration is a good time to look for these strays, the Southwest will often host both wintering and summering birds.
Eastern strays typically originate either from the tropics, or from Europe, with shorebirds and passerines among the most common. For example, the Northern Lapwing (left) has been seen in many states on the East Coast.
Florida strays typically come up from the nearby West Indies. Storms or natural wanderings may account for the appearance of birds like the Stripe-headed Tanager (right).
Many pelagic (seagoing) species freely roam the oceans and occasionally stray into our region, which is bordered by the sea, except for Mexico to the south, on all sides. An example is the Light-mantled Sooty Albatross, which strayed here all the way from the Southern Hemisphere.
Extinct or Extirpated
Some species, like the Ivory-billed Woodpecker (right), have not fared well with the recent increase in human population, technology, and habitat destruction, and are now extinct. Extirpated species are those that once resided in our region but no longer live here.
Exotics, like the cockatiel (right), are species not native to North America that have escaped from captivity or been released in our area. This category also includes sightings of birds that are not considered legitimate records as they have not been adequately scientifically documented.