Analyses of ancient dog DNA suggest that dogs were likely domesticated from Eurasian wolves around 23,000 years ago, possibly in Siberia.
Image credit: Pixabay/Chiemsee2016.
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Edited by Gordon H. Orians, University of Washington, Seattle, WA, and approved September 23, 2009 (received for review July 20, 2009)
Abstract
Neotropical migratory songbirds typically breed in temperate regions and then travel long distances to spend the majority of the annual cycle in tropical wintering areas. Using stable-isotope methodology, we provide quantitative evidence of dual breeding ranges for 5 species of Neotropical migrants. Each is well known to have a Neotropical winter range and a breeding range in the United States and Canada. However, after their first bout of breeding in the north, many individuals migrate hundreds to thousands of kilometers south in midsummer to breed a second time during the same summer in coastal west Mexico or Baja California Sur. They then migrate further south to their final wintering areas in the Neotropics. Our discovery of dual breeding ranges in Neotropical migrants reveals a hitherto unrealized flexibility in life-history strategies for these species and underscores that demographic models and conservation plans must consider dual breeding for these migrants.
Footnotes
- 1To whom correspondence should be addressed. E-mail: rohwer{at}u.washington.edu
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Author contributions: S.R., K.A.H., and V.G.R. designed research; S.R., K.A.H., and V.G.R. performed research; S.R. and V.G.R. analyzed data; and S.R., K.A.H., and V.G.R. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Migratory double breeding in Neotropical migrant birds
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