Table 5.

Factors affecting the extinction of birds (and other vertebrates) on oceanic islands

Extinction factor	Potentially promotes extinction	Potentially delays extinction
Abiotic factors
A1. Island size	Small	Large
A2. Topography	Flat, low	Steep, rugged
A3. Bedrock type	Sandy, or noncalcareous sedimentary	Limestone or knife-edge volcanics
A4. Soil type	Nutrient-rich	Nutrient-poor
A5. Isolation	Very isolated	Many nearby islands
A6. Climate	Seasonal aridity	Reliably wet
Indigenous biological factors
B1. Floral diversity	Depauperate	Rich (short-term delay only)
B2. Faunal diversity	Depauperate	Rich (short-term delay only)
B3. Terrestrial mammals	Absent*	Present
B4. Marine resources	Depauperate; difficult access	Rich (temporary delay only); easy access
B5. Species-specific ecological, behavioral, or morphological traits	Ground-dwelling; flightless; large; tame; fatty; good taste; colorful feathers; long and straight bones	Canopy-dwelling; volant; small; wary; little fat; bad taste; drab plumage; short and curved bones
Cultural factors
C1. Occupation	Permanent	Temporary
C2. Settlement pattern	Island-wide	Restricted (coastal)
C3. Population growth and density	Rapid growth; high density	Slow growth; low-density
C4. Subsistence	Farmers as well as h-f-g	H-f-g only, especially if marine-oriented
C5. Introduced plants	Many species; invasive	Few species; noninvasive
C6. Introduced animals	Many species; feral populations	Few or no species; no feral populations

From Steadman (ref. 3, table 16-5), except that conditions in columns 2 and 3 in italicized bold indicate when the general condition in the Bahamian Archipelago differs from that in the Greater Antilles. See text for additional information. h-f-g, hunter-fisher-gatherer.

^*Except the rodent Geocapromys ingrahami is indigenous on islands of the GBB.