Range (biology)

The three basic types of population distribution within an area. From top to bottom, spaced (uniform/regular), random and clumped (aggregated).

In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.

The term is often qualified:

• Sometimes a distinction is made between a species' natural, endemic, or native range where it historically originated and lived, and the range where a species has more recently established itself. Many terms are used to describe the new range, such as non-native, naturalized, introduced, transplanted, invasive, or colonized range.^[1] Introduced typically means that a species has been transported by humans (intentionally or accidentally) across a major geographical barrier.^[2]
• For species found in different regions at different times of year, terms such as summer range and winter range are often employed.
• For species for which only part of their range is used for breeding activity, the terms breeding range and non-breeding range are used.
• For mobile animals, the term natural range is often used, as opposed to areas where it occurs as a vagrant.
• Geographic or temporal qualifiers are often added: for example, British range or pre-1950 range.

There are at least five types of distribution patterns:

• Scattered/random (Random placement)
• Clustered/grouped (Most are placed in one area)
• Linear (Their placements form a line)
• Radial (Placements form an ' x ' shape)
• Regular/ordered (They are not random at all, but follow a set placement. Much like a grid)

Bird wildlife corridors

One common example of bird species' ranges are land mass areas bordering water bodies, such as oceans, rivers, or lakes; they are called a coastal strip. A second example, some species of bird depend on water, usually a river, swamp, etc., or water related forest and live in a river corridor. A separate example of a river corridor would be a river corridor that includes the entire drainage, having the edge of the range delimited by mountains, or higher elevations; the river itself would be a smaller percentage of this entire wildlife corridor, but the corridor is created because of the river.

A further example of a bird wildlife corridor would be a mountain range corridor. In the U.S. of North America, the Sierra Nevada range in the west, and the Appalachian Mountains in the east are two examples of this habitat, used in summer, and winter, by separate species, for different reasons.

Bird species in these corridors are connected to a main range for the species (contiguous) or are in an isolated geographic range and be a disjunct range. Birds leaving the area, if they migrate, would leave connected to the main range or have to fly over land not connected to the wildlife corridor; thus, they would be passage migrants over land that they stop on for an intermittent, hit or miss, visit.

See also

• Biological dispersal
• Colonisation
• Human–wildlife conflict
• Occupancy-abundance relationship
• Species distribution

References