Burke Museum and Department of Biology, University of Washington, Seattle, WA 98195, USA.
Proc Natl Acad Sci U S A. 2009 Nov 10;106(45):19050-5. doi: 10.1073/pnas.0908121106. Epub 2009 Oct 26.
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.
新热带区迁徙鸣禽通常在温带地区繁殖，然后长途迁徙到热带地区度过一年中的大部分时间。利用稳定同位素方法，我们为 5 种新热带区迁徙鸣禽提供了双重繁殖范围的定量证据。人们普遍知道这些物种在新热带区有冬季范围和在美国和加拿大的繁殖范围。然而，在北方完成第一次繁殖后，许多个体在仲夏向南迁徙数百至数千公里，在墨西哥沿海或下加利福尼亚州南部第二次繁殖，在同一夏季。然后它们进一步向南迁徙到新热带地区的最终越冬地。我们在新热带区迁徙鸣禽中发现的双重繁殖范围揭示了这些物种在生活史策略上迄今为止尚未实现的灵活性，并强调人口模型和保护计划必须考虑这些迁徙鸣禽的双重繁殖。
