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Causes of reduced clutch size in a tidal marsh endemic

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dc.contributor.author Olsen, Brian en
dc.contributor.author Felch, Joshua en
dc.contributor.author Greenberg, Russell S. en
dc.contributor.author Walters, Jeffrey en
dc.date.accessioned 2009-02-24T16:15:40Z
dc.date.available 2009-02-24T16:15:40Z
dc.date.issued 2008
dc.identifier.citation Olsen, Brian, Felch, Joshua, Greenberg, Russell S., and Walters, Jeffrey. 2008. "<a href="https://repository.si.edu/handle/10088/6941">Causes of reduced clutch size in a tidal marsh endemic</a>." <em>Oecologia</em>. 158 (3):421&ndash;435. <a href="https://doi.org/10.1007/s00442-008-1148-1">https://doi.org/10.1007/s00442-008-1148-1</a> en
dc.identifier.issn 0029-8549
dc.identifier.uri http://hdl.handle.net/10088/6941
dc.description.abstract Abstract We tested three hypotheses of clutch size variation in two subspecies of the swamp sparrow (Melospiza georgiana georgiana and M. g. nigrescens). Swamp sparrows follow the pattern of other estuarine endemics, where clutch size is smaller among tidal salt marsh populations (M. g. nigrescens) than their closest inland relatives (M. g. georgiana). Our results support predation risk and temperature, but not adult survival, as explanations of this pattern in swamp sparrows. Coastal nests were twice as likely to fail as inland nests, and parental activity around the nest site was positively related to clutch size at both sites. When brood size was controlled for, coastal adults visited nests less often and females vocalized less frequently during visits than inland birds, which may decrease nest detectability to predators. Coastal parents waited longer than inland birds to feed offspring in the presence of a model nest predator, but there was no difference in their response to models of predators of adults, as would be expected if coastal birds possessed increased longevity. Additionally, coastal females laid more eggs than inland females over a single season, following a within-season bet-hedging strategy rather than reducing within-season investment. Coastal territories experienced ambient air temperatures above the physiological zero of egg development more often, and higher temperatures during laying correlated with smaller clutches and increased egg inviability among coastal birds. Similar effects were not seen among inland nests, where laying temperatures were generally below physiological zero. Both subspecies showed an increase in hatching asynchrony and a decrease in apparent incubation length under high temperatures. Coastal individuals, however, showed less hatching asynchrony overall despite higher temperatures. Both air temperatures during laying and predation risk could potentially explain reduced clutch size in not only coastal plain swamp sparrows, but also other tidal marsh endemics. en
dc.format.extent 498822 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.relation.ispartof Oecologia en
dc.title Causes of reduced clutch size in a tidal marsh endemic en
dc.type Journal Article en
dc.identifier.srbnumber 76647
dc.identifier.doi 10.1007/s00442-008-1148-1
rft.jtitle Oecologia
rft.volume 158
rft.issue 3
rft.spage 421
rft.epage 435
dc.description.SIUnit NZP en
dc.description.SIUnit crc en
dc.description.SIUnit mbc en
dc.citation.spage 421
dc.citation.epage 435


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