Broad-scale environmental influences on the abundance of saltwater crocodiles (Crocodylus porosus) in Australia

Yusuke Fukuda, Peter Whitehead, Guy Boggs

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Saltwater crocodile (Crocodylus porosus) populations have recovered strongly across northern Australia over the 30 years since the species was protected from hunting. However, monitoring studies show large geographical variations in abundance across the Northern Territory, Queensland and Western Australia. The Northern Territory has considerably higher densities, raising questions about constraints on recovery in the other states. We examined broad-scale environmental influences on population abundance by modelling the species-environment relationships across northern Australia. The hypothesis-based models showed strong support for the linkage to (1) the ratio of total area of favourable wetland vegetation types (Melaleuca, grass and sedge to total catchment area, (2) a measure of rainfall seasonality, namely the ratio of total precipitation in the coldest quarter to total precipitation in the warmest quarter of a year, and (3) the mean temperature in the coldest quarter of a year. On the other hand, we were unable to show any clear negative association with landscape modification, as indicated by the extent of high-impact land uses or human population density in catchments. We conclude that geographical variations in crocodile density are mostly attributable to differences in habitat quality rather than the management regimes adopted in the respective jurisdictions. � CSIRO 2007.
    Original languageEnglish
    Pages (from-to)167-176
    Number of pages10
    JournalWildlife Research
    Volume34
    Issue number3
    Publication statusPublished - 2007

    Fingerprint

    Crocodylus porosus
    Northern Territory
    geographical variation
    Melaleuca
    crocodiles
    sedge
    habitat quality
    human population
    vegetation types
    Western Australia
    vegetation type
    hunting
    Queensland
    seasonality
    population density
    wetlands
    land use
    wetland
    grass
    catchment

    Cite this

    Fukuda, Yusuke ; Whitehead, Peter ; Boggs, Guy. / Broad-scale environmental influences on the abundance of saltwater crocodiles (Crocodylus porosus) in Australia. In: Wildlife Research. 2007 ; Vol. 34, No. 3. pp. 167-176.
    @article{7ae37588616b48439ac55f9858570a3b,
    title = "Broad-scale environmental influences on the abundance of saltwater crocodiles (Crocodylus porosus) in Australia",
    abstract = "Saltwater crocodile (Crocodylus porosus) populations have recovered strongly across northern Australia over the 30 years since the species was protected from hunting. However, monitoring studies show large geographical variations in abundance across the Northern Territory, Queensland and Western Australia. The Northern Territory has considerably higher densities, raising questions about constraints on recovery in the other states. We examined broad-scale environmental influences on population abundance by modelling the species-environment relationships across northern Australia. The hypothesis-based models showed strong support for the linkage to (1) the ratio of total area of favourable wetland vegetation types (Melaleuca, grass and sedge to total catchment area, (2) a measure of rainfall seasonality, namely the ratio of total precipitation in the coldest quarter to total precipitation in the warmest quarter of a year, and (3) the mean temperature in the coldest quarter of a year. On the other hand, we were unable to show any clear negative association with landscape modification, as indicated by the extent of high-impact land uses or human population density in catchments. We conclude that geographical variations in crocodile density are mostly attributable to differences in habitat quality rather than the management regimes adopted in the respective jurisdictions. � CSIRO 2007.",
    keywords = "abundance, catchment, crocodilian, environmental effect, geographical variation, habitat quality, land use, landscape change, population density, precipitation intensity, temperature effect, vegetation type, Australasia, Australia, Queensland, Alligator, Crocodylus porosus, Melaleuca",
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    Broad-scale environmental influences on the abundance of saltwater crocodiles (Crocodylus porosus) in Australia. / Fukuda, Yusuke; Whitehead, Peter; Boggs, Guy.

    In: Wildlife Research, Vol. 34, No. 3, 2007, p. 167-176.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

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    AU - Fukuda, Yusuke

    AU - Whitehead, Peter

    AU - Boggs, Guy

    PY - 2007

    Y1 - 2007

    N2 - Saltwater crocodile (Crocodylus porosus) populations have recovered strongly across northern Australia over the 30 years since the species was protected from hunting. However, monitoring studies show large geographical variations in abundance across the Northern Territory, Queensland and Western Australia. The Northern Territory has considerably higher densities, raising questions about constraints on recovery in the other states. We examined broad-scale environmental influences on population abundance by modelling the species-environment relationships across northern Australia. The hypothesis-based models showed strong support for the linkage to (1) the ratio of total area of favourable wetland vegetation types (Melaleuca, grass and sedge to total catchment area, (2) a measure of rainfall seasonality, namely the ratio of total precipitation in the coldest quarter to total precipitation in the warmest quarter of a year, and (3) the mean temperature in the coldest quarter of a year. On the other hand, we were unable to show any clear negative association with landscape modification, as indicated by the extent of high-impact land uses or human population density in catchments. We conclude that geographical variations in crocodile density are mostly attributable to differences in habitat quality rather than the management regimes adopted in the respective jurisdictions. � CSIRO 2007.

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    KW - landscape change

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