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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>R. G. Clark</dc:contributor>
  <dc:contributor>A. D. Afton</dc:contributor>
  <dc:creator>J.J. Rotella</dc:creator>
  <dc:date>2003</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;In birds, larger females generally have greater breeding propensity,&amp;nbsp;&lt;/span&gt;reproductive&lt;span&gt;&amp;nbsp;investment, and success than do smaller females. However, optimal&amp;nbsp;&lt;/span&gt;female&lt;span&gt;&amp;nbsp;&lt;/span&gt;body&lt;span&gt;&amp;nbsp;&lt;/span&gt;size&lt;span&gt;&amp;nbsp;also depends on how natural selection acts during other parts of the life cycle. Larger&amp;nbsp;&lt;/span&gt;female&lt;span&gt;&amp;nbsp;&lt;/span&gt;Lesser&lt;span&gt;&amp;nbsp;&lt;/span&gt;Scaup&lt;span&gt;&amp;nbsp;(Aythya affinis) produce larger eggs than do smaller females, and ducklings from larger eggs survive better than those hatching from smaller eggs. Accordingly, we examined patterns of apparent annual&amp;nbsp;&lt;/span&gt;survival&lt;span&gt;&amp;nbsp;for&amp;nbsp;&lt;/span&gt;female&lt;span&gt;&amp;nbsp;&lt;/span&gt;scaup&lt;span&gt;&amp;nbsp;and tested whether natural selection on&amp;nbsp;&lt;/span&gt;female&lt;span&gt;&amp;nbsp;&lt;/span&gt;body&lt;span&gt;&amp;nbsp;&lt;/span&gt;size&lt;span&gt;&amp;nbsp;primarily was stabilizing, a frequent assumption in studies of sexually dimorphic species in which males are the larger sex, or was directional, counter-acting&amp;nbsp;&lt;/span&gt;reproductive&lt;span&gt;&amp;nbsp;advantages of large&amp;nbsp;&lt;/span&gt;size&lt;span&gt;. We estimated&amp;nbsp;&lt;/span&gt;survival&lt;span&gt;&amp;nbsp;using mark-recapture methods for individually marked females from two study sites in Canada (Erickson, Manitoba; St. Denis, Saskatchewan). Structurally larger (adults) and heavier (ducklings) females had lower&amp;nbsp;&lt;/span&gt;survival&lt;span&gt;&amp;nbsp;than did smaller individuals in Manitoba; no relationship was detected in adults from Saskatchewan.&amp;nbsp;&lt;/span&gt;Survival&lt;span&gt;&amp;nbsp;of adult females declined with indices of increasing&amp;nbsp;&lt;/span&gt;reproductive&lt;span&gt;&amp;nbsp;&lt;/span&gt;effort&lt;span&gt;&amp;nbsp;at both sites; consequently, the cost of reproduction could explain&amp;nbsp;&lt;/span&gt;age&lt;span&gt;-related patterns of breeding propensity in&amp;nbsp;&lt;/span&gt;scaup&lt;span&gt;. Furthermore, if larger females are more likely to breed than are smaller females, then cost of reproduction also may help explain why&amp;nbsp;&lt;/span&gt;survival&lt;span&gt;&amp;nbsp;was lower for larger females. Overall, we found that advantages of large&amp;nbsp;&lt;/span&gt;body&lt;span&gt;&amp;nbsp;&lt;/span&gt;size&lt;span&gt;&amp;nbsp;of&amp;nbsp;&lt;/span&gt;female&lt;span&gt;&amp;nbsp;&lt;/span&gt;scaup&lt;span&gt;&amp;nbsp;during breeding or as young ducklings apparently were counteracted by natural selection favoring lightweight juveniles and structurally smaller adult females through higher annual&amp;nbsp;&lt;/span&gt;survival&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1650/0010-5422(2003)105[0336:SOFLSE]2.0.CO;2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Ornithologist Society</dc:publisher>
  <dc:title>Survival of female Lesser Scaup: Effects of body size, age, and reproductive effort</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>