Male sex-ratio bias in the endangered South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus

Joannah Lee, Lynn Pedler, Stephen SARRE, James ROBERTSON, Leo Joseph

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging.
    Original languageEnglish
    Pages (from-to)356-359
    Number of pages4
    JournalEmu
    Volume115
    Issue number4
    DOIs
    Publication statusPublished - 2015

    Fingerprint

    nestling
    sex ratio
    sex determination analysis
    fledging
    gender
    census
    DNA
    mortality
    plumage
    Psittaciformes
    isolated population
    census data
    Macropodidae
    hatching
    adulthood
    bird
    Cacatuidae
    nestlings
    birds
    testing

    Cite this

    Lee, Joannah ; Pedler, Lynn ; SARRE, Stephen ; ROBERTSON, James ; Joseph, Leo. / Male sex-ratio bias in the endangered South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus. In: Emu. 2015 ; Vol. 115, No. 4. pp. 356-359.
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    abstract = "Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging.",
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    Male sex-ratio bias in the endangered South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus. / Lee, Joannah; Pedler, Lynn; SARRE, Stephen; ROBERTSON, James; Joseph, Leo.

    In: Emu, Vol. 115, No. 4, 2015, p. 356-359.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Male sex-ratio bias in the endangered South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus

    AU - Lee, Joannah

    AU - Pedler, Lynn

    AU - SARRE, Stephen

    AU - ROBERTSON, James

    AU - Joseph, Leo

    PY - 2015

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    N2 - Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging.

    AB - Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging.

    KW - wildlife

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