Brood reduction and parental effort in the yellow-headed blackbird (Xanthocephalus xanthocephalus) / Richard Eric Grosshans.
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TextSeries: ThesisPublication details: Winnipeg, MB : 1994. University of Winnipeg,Description: viii, 51 leaves : ill. ; 28 cmOnline resources: Abstract: Brood reduction (= partial brood loss), where brood size is matched to food supplied operating through sibling competition, occurs in many birds. Parents may enhance this process by hatching chicks asynchronously, facilitating chick loss when food is scarce. In the spring of 1993, I studied brood reduction in a populations of yellow-headed blackbirds, Xanthocephalus xanthocephalus, near Winnipeg,MB. Lack's (1947) brood reduction hypothesis predicts that last-hatched nestlings are the first to perish when food is scarce. If chicks were artifically synchronized, we would expect higher fledging success during times when food is abundant, and higher chick mortality when food is scarce. Such synchronization experiments, however, are confounded when parents alter their normal work levels: survival of nestlings in synchronized broods may not decline if parents step up food deliveries.I tested the implicit assumption of Lack's hypothesis that parents do NOT alter work levels in response to
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"A thesis presented to the University of Winnipeg in fulfillment of the requirements for the Projects in Biology course."
Includes bibliographical references (leaves 48-50).
Brood reduction (= partial brood loss), where brood size is matched to food supplied operating through sibling competition, occurs in many birds. Parents may enhance this process by hatching chicks asynchronously, facilitating chick loss when food is scarce. In the spring of 1993, I studied brood reduction in a populations of yellow-headed blackbirds, Xanthocephalus xanthocephalus, near Winnipeg,MB. Lack's (1947) brood reduction hypothesis predicts that last-hatched nestlings are the first to perish when food is scarce. If chicks were artifically synchronized, we would expect higher fledging success during times when food is abundant, and higher chick mortality when food is scarce. Such synchronization experiments, however, are confounded when parents alter their normal work levels: survival of nestlings in synchronized broods may not decline if parents step up food deliveries.I tested the implicit assumption of Lack's hypothesis that parents do NOT alter work levels in response to