title: Eggshell porosity covaries with egg size among female House Wrens (Troglodytes aedon) but is unrelated to incubation onset and egg-laying order within clutches.
abstract: In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens (Troglodytes aedonVieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns.
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA.
authors.forename: E K
authors.initials: EK
authors.lastname: Bowers
authors.affiliation: Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
authors.forename: A
authors.initials: A
authors.lastname: White
authors.affiliation: Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
authors.forename: A
authors.initials: A
authors.lastname: Lang
authors.affiliation: Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
authors.forename: L
authors.initials: L
authors.lastname: Podgorski
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Thompson
authors.affiliation: Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Sakaluk
authors.affiliation: Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Jaeckle
authors.affiliation: Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Harper
keywords: House Wren; Troglodytes aedon; egg; eggshell porosity; hatching asynchrony; incubation behavior; onset of incubation