Speckled eggs

Water-loss and incubation behaviour in the great tit Parus major

James Higham, Andrew G. Gosler

    Research output: Contribution to journalArticle

    Abstract

    Many small passerine birds worldwide lay white eggs speckled with red, brown and black protoporphyrin pigment spots (maculation). Unlike some patterns of avian eggshell pigmentation which clearly serve a crypsis or signalling function, the ubiquity of maculation among passerines suggests that its origins lie in another function, not specific to any particular ecological or behavioural group. Elsewhere, we have presented evidence that protoporphyrin pigments serve a structural function related to eggshell thickness and calcium availability: eggshell maculation in the great tit Parus major increases with decreasing soil calcium levels, pigments demarcate thinner areas of shell, and both the pigment intensity and distribution are related to shell thickness. Here we show that maculation also affects the rate of water loss from the egg during incubation (≈ Mass Loss per Day or MLD, which is critical to egg viability), but not that of unincubated eggs. We also demonstrate, both by observation and experiment, that the effect of female incubation behaviour on MLD compensates in some way for variation in egg characteristics, and that differences between females in the degree of such compensation are related to differences in clutch maculation. Our results suggest that, while a principal function of maculation in this species may be to strengthen the eggshell, it may also reduce eggshell permeability when large amounts of pigment are used, and that this necessitates a behavioural adjustment from the female during incubation. We discuss these findings and make further testable predictions from our model.

    Original languageEnglish (US)
    Pages (from-to)561-570
    Number of pages10
    JournalOecologia
    Volume149
    Issue number4
    DOIs
    StatePublished - Oct 2006

    Fingerprint

    eggshell
    Parus major
    pigment
    egg shell
    incubation
    pigments
    egg
    protoporphyrin
    passerine
    water
    calcium
    shell
    crypsis
    egg shell thickness
    egg incubation
    egg albumen
    egg quality
    pigmentation
    permeability
    viability

    Keywords

    • Eggshell-maculation
    • Eggshell-permeability
    • Incubation behaviour
    • Pigmentation

    ASJC Scopus subject areas

    • Ecology

    Cite this

    Speckled eggs : Water-loss and incubation behaviour in the great tit Parus major. / Higham, James; Gosler, Andrew G.

    In: Oecologia, Vol. 149, No. 4, 10.2006, p. 561-570.

    Research output: Contribution to journalArticle

    Higham, James ; Gosler, Andrew G. / Speckled eggs : Water-loss and incubation behaviour in the great tit Parus major. In: Oecologia. 2006 ; Vol. 149, No. 4. pp. 561-570.
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