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Human impacts on the rates of recent, present, and future bird extinctions.

Abstract：

:Unqualified, the statement that approximately 1.3% of the approximately 10,000 presently known bird species have become extinct since A.D. 1500 yields an estimate of approximately 26 extinctions per million species per year (or 26 E/MSY). This is higher than the benchmark rate of approximately 1 E/MSY before human impacts, but is a serious underestimate. First, Polynesian expansion across the Pacific also exterminated many species well before European explorations. Second, three factors increase the rate: (i) The number of known extinctions before 1800 is increasing as taxonomists describe new species from skeletal remains. (ii) One should calculate extinction rates over the years since taxonomists described the species. Most bird species were described only after 1850. (iii) Some species are probably extinct; there is reluctance to declare them so prematurely. Thus corrected, recent extinction rates are approximately 100 E/MSY. In the last decades, the rate is <50 E/MSY, but would be 150 E/MSY were it not for conservation efforts. Increasing numbers of extinctions are on continents, whereas previously most were on islands. We predict a 21st century rate of approximately 1,000 E/MSY. Extinction threatens 12% of bird species; another 12% have small geographical ranges and live where human actions rapidly destroy their habitats. If present forest losses continue, extinction rates will reach 1,500 E/MSY by the century's end. Invasive species, expanding human technologies, and global change will harm additional species. Birds are poor models for predicting extinction rates for other taxa. Human actions threaten higher fractions of other well known taxa than they do birds. Moreover, people take special efforts to protect birds.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Pimm S,Raven P,Peterson A,Sekercioglu CH,Ehrlich PR

doi

10.1073/pnas.0604181103

subject

Has Abstract

pub_date

2006-07-18 00:00:00

pages

10941-6

issue

eissn

0027-8424

issn

1091-6490

pii

0604181103

journal_volume

103

pub_type

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Human impacts on the rates of recent, present, and future bird extinctions.