If you need an accessible version of this item please contact JSTOR User Support

The Adaptive Significance of Some Size Trends in Island Birds

P. R. Grant
Evolution
Vol. 19, No. 3 (Sep., 1965), pp. 355-367
DOI: 10.2307/2406446
Stable URL: http://www.jstor.org/stable/2406446
Page Count: 13
  • Download PDF
  • Cite this Item

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support
The Adaptive Significance of Some Size Trends in Island Birds
Preview not available

Abstract

1. In North America and México there is a strong tendency for island birds to have a longer tarsus and bill than their mainland counterparts; but there is no such tendency for them to have a longer wing and tail. 2. Although climate and body-size are known to influence the size of tarsus and bill the larger dimensions on islands are considered to be adaptations primarily to ecological conditions. The bill is longer because it deals with a greater range of food-sizes, and the tarsus is longer because a greater variety of perches is used. 3. The differences in usage have arisen as a result of the absence, on the islands, of species with similar ecological requirements, which has permitted some of those present to extend their activities and occupy at least part of the vacant niches, sometimes in new habitats. 4. It is suggested that the same ecological conditions and responses have influenced the evolution of large body-size of island rodents in particular, and of mainland animals of several phyla in general.

Page Thumbnails

  • Thumbnail: Page 
355
    355
  • Thumbnail: Page 
356
    356
  • Thumbnail: Page 
357
    357
  • Thumbnail: Page 
358
    358
  • Thumbnail: Page 
359
    359
  • Thumbnail: Page 
360
    360
  • Thumbnail: Page 
361
    361
  • Thumbnail: Page 
362
    362
  • Thumbnail: Page 
363
    363
  • Thumbnail: Page 
364
    364
  • Thumbnail: Page 
365
    365
  • Thumbnail: Page 
366
    366
  • Thumbnail: Page 
367
    367