Back to the brink: Population decline of the endangered grassland earless dragon (tympanocryptis pinguicolla) following its rediscovery

Wendy Dimond, William Osborne, Murray Evans, Bernd Gruber, Stephen Sarre

    Research output: Contribution to journalArticle

    10 Citations (Scopus)

    Abstract

    Lizard populations are under serious threat through widespread decline and predictions of multiple extinctions through climate change. Yet detecting specific instances of decline remains problematic in many situations because of inconsistent and sparse data. We assessed the stability of populations of the endangered Grassland Earless Dragons (Tympanocryptis pinguicolla) conducted after its rediscovery using capture rates at 10 sites (from 23 surveyed) and survival and population size estimation at one intensively studied site. We show a gradual non-significant decline in population size across all sites from 1995 followed by a dramatic reduction (88%) from 2006 at the most densely populated site. Using mark-recapture-release approaches, we estimate annual survival at that site to be low (0.017 to one year of age and 0.024 to adulthood) over the three years of the study. Taken together, these data suggest a regional decline among T. pinguicolla populations that place the species in grave jeopardy of becoming the first confirmed reptile extinction in Australia since European settlement. The key factors for basing further hypothesis driven monitoring include drought habitat cover (or the effects of grazing) and habitat fragmentation. We agree with other conservationists that for highly endangered species, there may not be the time required to conduct long-term monitoring. However, by making good use of even disparate past surveys, a case can be made for trends in population size. We urge that even data collected in an ad hoc manner be examined to help plan management programs for rare or endangered species.
    Original languageEnglish
    Pages (from-to)132-149
    Number of pages18
    JournalHerpetological Conservation and Biology
    Volume7
    Issue number2
    Publication statusPublished - 2012

    Fingerprint

    population decline
    population size
    grasslands
    grassland
    endangered species
    extinction
    mark-recapture studies
    monitoring
    habitat fragmentation
    rare species
    adulthood
    reptile
    lizard
    reptiles
    lizards
    grazing
    drought
    climate change
    prediction
    habitat

    Cite this

    @article{388f2f17b4214fdb963dbdf23328cb3c,
    title = "Back to the brink: Population decline of the endangered grassland earless dragon (tympanocryptis pinguicolla) following its rediscovery",
    abstract = "Lizard populations are under serious threat through widespread decline and predictions of multiple extinctions through climate change. Yet detecting specific instances of decline remains problematic in many situations because of inconsistent and sparse data. We assessed the stability of populations of the endangered Grassland Earless Dragons (Tympanocryptis pinguicolla) conducted after its rediscovery using capture rates at 10 sites (from 23 surveyed) and survival and population size estimation at one intensively studied site. We show a gradual non-significant decline in population size across all sites from 1995 followed by a dramatic reduction (88{\%}) from 2006 at the most densely populated site. Using mark-recapture-release approaches, we estimate annual survival at that site to be low (0.017 to one year of age and 0.024 to adulthood) over the three years of the study. Taken together, these data suggest a regional decline among T. pinguicolla populations that place the species in grave jeopardy of becoming the first confirmed reptile extinction in Australia since European settlement. The key factors for basing further hypothesis driven monitoring include drought habitat cover (or the effects of grazing) and habitat fragmentation. We agree with other conservationists that for highly endangered species, there may not be the time required to conduct long-term monitoring. However, by making good use of even disparate past surveys, a case can be made for trends in population size. We urge that even data collected in an ad hoc manner be examined to help plan management programs for rare or endangered species.",
    keywords = "Agamid, Grassland Earless Dragon, management, mark recapture, natural temperate grassland, population trend, survival, Tympanocryptis pinguicolla",
    author = "Wendy Dimond and William Osborne and Murray Evans and Bernd Gruber and Stephen Sarre",
    year = "2012",
    language = "English",
    volume = "7",
    pages = "132--149",
    journal = "Herpetological Conservation and Biology",
    issn = "1931-7603",
    publisher = "Herpetological Conservation and Biology",
    number = "2",

    }

    Back to the brink: Population decline of the endangered grassland earless dragon (tympanocryptis pinguicolla) following its rediscovery. / Dimond, Wendy; Osborne, William; Evans, Murray; Gruber, Bernd; Sarre, Stephen.

    In: Herpetological Conservation and Biology, Vol. 7, No. 2, 2012, p. 132-149.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Back to the brink: Population decline of the endangered grassland earless dragon (tympanocryptis pinguicolla) following its rediscovery

    AU - Dimond, Wendy

    AU - Osborne, William

    AU - Evans, Murray

    AU - Gruber, Bernd

    AU - Sarre, Stephen

    PY - 2012

    Y1 - 2012

    N2 - Lizard populations are under serious threat through widespread decline and predictions of multiple extinctions through climate change. Yet detecting specific instances of decline remains problematic in many situations because of inconsistent and sparse data. We assessed the stability of populations of the endangered Grassland Earless Dragons (Tympanocryptis pinguicolla) conducted after its rediscovery using capture rates at 10 sites (from 23 surveyed) and survival and population size estimation at one intensively studied site. We show a gradual non-significant decline in population size across all sites from 1995 followed by a dramatic reduction (88%) from 2006 at the most densely populated site. Using mark-recapture-release approaches, we estimate annual survival at that site to be low (0.017 to one year of age and 0.024 to adulthood) over the three years of the study. Taken together, these data suggest a regional decline among T. pinguicolla populations that place the species in grave jeopardy of becoming the first confirmed reptile extinction in Australia since European settlement. The key factors for basing further hypothesis driven monitoring include drought habitat cover (or the effects of grazing) and habitat fragmentation. We agree with other conservationists that for highly endangered species, there may not be the time required to conduct long-term monitoring. However, by making good use of even disparate past surveys, a case can be made for trends in population size. We urge that even data collected in an ad hoc manner be examined to help plan management programs for rare or endangered species.

    AB - Lizard populations are under serious threat through widespread decline and predictions of multiple extinctions through climate change. Yet detecting specific instances of decline remains problematic in many situations because of inconsistent and sparse data. We assessed the stability of populations of the endangered Grassland Earless Dragons (Tympanocryptis pinguicolla) conducted after its rediscovery using capture rates at 10 sites (from 23 surveyed) and survival and population size estimation at one intensively studied site. We show a gradual non-significant decline in population size across all sites from 1995 followed by a dramatic reduction (88%) from 2006 at the most densely populated site. Using mark-recapture-release approaches, we estimate annual survival at that site to be low (0.017 to one year of age and 0.024 to adulthood) over the three years of the study. Taken together, these data suggest a regional decline among T. pinguicolla populations that place the species in grave jeopardy of becoming the first confirmed reptile extinction in Australia since European settlement. The key factors for basing further hypothesis driven monitoring include drought habitat cover (or the effects of grazing) and habitat fragmentation. We agree with other conservationists that for highly endangered species, there may not be the time required to conduct long-term monitoring. However, by making good use of even disparate past surveys, a case can be made for trends in population size. We urge that even data collected in an ad hoc manner be examined to help plan management programs for rare or endangered species.

    KW - Agamid

    KW - Grassland Earless Dragon

    KW - management

    KW - mark recapture

    KW - natural temperate grassland

    KW - population trend

    KW - survival

    KW - Tympanocryptis pinguicolla

    M3 - Article

    VL - 7

    SP - 132

    EP - 149

    JO - Herpetological Conservation and Biology

    JF - Herpetological Conservation and Biology

    SN - 1931-7603

    IS - 2

    ER -