Mechanisms Underlying Intra-seasonal Variation in the Risk of Avian Nest Predation: Implications for Breeding Phenology

Persistent Link:
http://hdl.handle.net/10150/195002
Title:
Mechanisms Underlying Intra-seasonal Variation in the Risk of Avian Nest Predation: Implications for Breeding Phenology
Author:
Borgmann, Kathi Louise
Issue Date:
2010
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Predation is an important ecological process that shapes life-history traits, community dynamics, and species coexistence and therefore has been suggested to explain many patterns in avian ecology. Although many studies have reported spatial, temporal, or interspecific patterns in nest predation, relatively few studies have been designed to identify the specific mechanism(s) that underlie these patterns. I examined mechanisms underlying the risk of nest predation in birds by (1) reviewing nine of the most commonly cited hypotheses to explain spatial, temporal, and interspecific variation in the risk of nest predation, (2) conducting a comparative analysis of the nest-concealment hypothesis to examine which methodological issues, extrinsic factors, and species traits influence whether or not foliage density affects the risk of nest predation, and (3) testing six mechanistic hypotheses to determine the underlying cause(s) of intra-seasonal decreases in the risk of nest predation.Many of the hypotheses invoked to explain spatial, temporal, and interspecific variation in the risk of nest predation lack clearly defined mechanisms. I suggest that future studies explicitly define the mechanism and assumption(s) of each hypothesis prior to implementing empirical tests.I found that the discrepancy in results among past studies that have examined the nest-concealment hypothesis was due to interspecific differences in a variety of intrinsic and extrinsic factors that affect nest predation but have previously been ignored. The effects of nest concealment on nest placement and probability of nest predation vary among species and this variation is predictable based on the bird's morphological traits and characteristics of the ecosystem.Increased risk of nest predation early in the breeding season appears to be due, in part, to foliage phenology and spatial and temporal changes in predator behavior. The risk of nest predation was negatively associated with foliage density early, but not late, in the breeding season. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests located near feeders. I show that intra-seasonal changes in environmental features and predator behavior affect patterns of nest predation, which can influence timing of breeding.
Type:
text; Electronic Dissertation
Keywords:
Breeding phenology; Foliage density; Nest concealment; Nest predation; Phenology
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Natural Resources; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Conway, Courtney J; Morrison, Michael L.
Committee Chair:
Conway, Courtney J

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleMechanisms Underlying Intra-seasonal Variation in the Risk of Avian Nest Predation: Implications for Breeding Phenologyen_US
dc.creatorBorgmann, Kathi Louiseen_US
dc.contributor.authorBorgmann, Kathi Louiseen_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPredation is an important ecological process that shapes life-history traits, community dynamics, and species coexistence and therefore has been suggested to explain many patterns in avian ecology. Although many studies have reported spatial, temporal, or interspecific patterns in nest predation, relatively few studies have been designed to identify the specific mechanism(s) that underlie these patterns. I examined mechanisms underlying the risk of nest predation in birds by (1) reviewing nine of the most commonly cited hypotheses to explain spatial, temporal, and interspecific variation in the risk of nest predation, (2) conducting a comparative analysis of the nest-concealment hypothesis to examine which methodological issues, extrinsic factors, and species traits influence whether or not foliage density affects the risk of nest predation, and (3) testing six mechanistic hypotheses to determine the underlying cause(s) of intra-seasonal decreases in the risk of nest predation.Many of the hypotheses invoked to explain spatial, temporal, and interspecific variation in the risk of nest predation lack clearly defined mechanisms. I suggest that future studies explicitly define the mechanism and assumption(s) of each hypothesis prior to implementing empirical tests.I found that the discrepancy in results among past studies that have examined the nest-concealment hypothesis was due to interspecific differences in a variety of intrinsic and extrinsic factors that affect nest predation but have previously been ignored. The effects of nest concealment on nest placement and probability of nest predation vary among species and this variation is predictable based on the bird's morphological traits and characteristics of the ecosystem.Increased risk of nest predation early in the breeding season appears to be due, in part, to foliage phenology and spatial and temporal changes in predator behavior. The risk of nest predation was negatively associated with foliage density early, but not late, in the breeding season. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests located near feeders. I show that intra-seasonal changes in environmental features and predator behavior affect patterns of nest predation, which can influence timing of breeding.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectBreeding phenologyen_US
dc.subjectFoliage densityen_US
dc.subjectNest concealmenten_US
dc.subjectNest predationen_US
dc.subjectPhenologyen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineNatural Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorConway, Courtney Jen_US
dc.contributor.advisorMorrison, Michael L.en_US
dc.contributor.chairConway, Courtney Jen_US
dc.contributor.committeememberMorrison, Michael L.en_US
dc.contributor.committeememberBadyaev, Alex V.en_US
dc.contributor.committeememberSteidl, Robert J.en_US
dc.identifier.proquest11309en_US
dc.identifier.oclc752261157en_US
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