Register      Login
Australian Journal of Zoology Australian Journal of Zoology Society
Evolutionary, molecular and comparative zoology
Shopping Cart: ( empty )
You are here: Home > Journals > ZO > ZO06099
RESEARCH ARTICLE
Contents Vol 54(6)

Growth dynamics of freshwater crocodiles (Crocodylus johnstoni) in the Lynd River, Queensland

Anton D. Tucker A E , Colin J. Limpus B , Keith R. McDonald C and Hamish I. McCallum A D
+ Author Affiliations
- Author Affiliations

A Zoology Department, University of Queensland, Brisbane, Qld 4072, Australia.

B Queensland Parks and Wildlife Service, PO Box 155, Brisbane, Qld 4002, Australia.

C Queensland Department of Environment and Heritage, PO Box 975, Atherton, Qld 4883, Australia.

D Present address: School of Zoology, University of Tasmania, Private Bag 5, Hobart, Tas. 7001, Australia.

E Corresponding author. Present address: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA. Email: tucker@mote.org

Australian Journal of Zoology 54(6) 409-415 https://doi.org/10.1071/ZO06099
Submitted: 27 November 2006  Accepted: 27 November 2006   Published: 9 January 2007

Abstract

We analysed growth models for a population of Australian freshwater crocodiles (Crocodylus johnstoni). Competing growth models were tested with two data sets: individuals of known-age, and growth interval data from capture-recapture records. A von Bertalanffy function provided the best empirical fit of several growth models. The estimated asymptotic lengths (snout–vent length of males = 125.3 cm; females = 97.4 cm) agreed well with average lengths of the ten largest males and females in the population. Sexual size dimorphism in this species resulted from a combination of smaller mean length at maturity for females and a subsequent decline in female growth rate. Size dimorphism may result from individual trade-offs in age v. length at maturity as a consequence of sexual selection.


Acknowledgments

The field study was initiated by the Queensland Parks and Wildlife Service (QPWS). We thank the many volunteers who helped to capture and process crocodiles between 1976 and 1995. Owners of Springfield, Burlington and Amber Stations granted access to the study site. The study received support from the Australian Research Council, the Centre for Conservation Biology at the University of Queensland, and an Overseas Postgraduate Research Scholarship to A. Tucker. Studies were conducted under permits from QPWS and with animal ethics approval from the University of Queensland. G. Webb and B. Magnusson provided constructive criticism on early versions of the manuscript.


References

Abercrombie C. L. (1992). Fitting curves to crocodilian age-size data: some hesitant recommendations. In ‘Proceedings of the 11th Working Meeting, Crocodile Specialists Group.’ pp. 5–21.

Adolph, S. C. , and Porter, W. P. (1996). Growth, seasonality, and lizard life histories: age and size at maturity. Oikos 77, 267–278.
| Crossref | GoogleScholarGoogle Scholar | Andrews R. M. (1982). Patterns of growth in reptiles. In ‘Biology of the Reptilia, Vol. 13’. (Eds C. Gans and F. H. Pough.) pp. 273–320. (Academic Press: New York.)

Bossert D., Chabreck R. H., and Wright V. L. (2000). Growth of farm-released and wild alligators in a Louisiana freshwater marsh. In ‘Crocodilian Biology and Evolution’. (Eds G. C. Grigg, F. Seebacher and C. Franklin.) pp. 419–425. (Surrey Beatty: Chipping Norton.)

Brisbin I. L.Jr. (1987). Growth curve analyses and their application to the conservation and captive management of crocodilians. ‘Proceedings of the 9th Working Meeting IUCN Crocodile Specialist Group’. pp. 116–145.

Chabreck, R. H. , and Joanen, T. (1979). Growth rates of American alligators in Louisiana. Herpetologica 35, 51–57.
Cooper-Preston H. (1992). Geographic variation in the population dynamics of Crocodylus johnstoni Krefft) in three rivers in the Northern Territory, Australia. PhD Thesis, University of New England.

Delany, M. F. , and Abercrombie, C. L. (1986). American alligator food habits in north central Florida. The Journal of Wildlife Management 50, 348–353.
de Ricqles A. J. (1975). On bone histology of fossil and living reptiles, with comments on its functional and evolutionary significance. In ‘Morphology and Biology of Reptiles’. (Eds A. Bellairs and C. B. Cox.) pp. 211–216. (Academic Press: New York.)

Dodson, P. (1975). Functional and ecological significance of relative growth in Alligator. Journal of Zoology 175, 3145–3155.
Joanen T., McNease L., and Ferguson M. W. J. (1987). The effects of egg incubation temperature on post-hatching growth of American alligators. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 533–537. (Surrey Beatty: Chipping Norton.)

Kaufmann, K. W. (1981). Fitting and using growth curves. Oecologia 49, 293–299.
| Crossref | GoogleScholarGoogle Scholar | Lang J. W. (1987). Crocodilian behavior: implications for management. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 273–294. (Surrey Beatty: Chipping Norton.)

Limpus, C. J. (1984). Identification of ovarian follicles and oviducal eggs by loacal examination of live Australian freshwater crocodiles, Crocodylus johnstoni. Australian Wildlife Research 11, 203–204.
| Crossref | GoogleScholarGoogle Scholar | Smith A. M. A. (1987). The sex and survivorship of embryos and hatchlings of the Australian freshwater crocodile (Crocodylus johnstoni). PhD Thesis, Australian National University.

Stearns, S. C. , and Koella, J. (1986). The evolution of phenotypic plasticity in life-history traits: predictions for norms of reaction for age- and size-at-maturity. Evolution 40, 893–913.
| Crossref | GoogleScholarGoogle Scholar | Tucker A. D. (1997a). Ecology and demography of freshwater crocodiles (Crocodylus johnstoni) in the Lynd River of north Queensland. PhD Thesis, University of Queensland.

Tucker, A. D. (1997b). Skeletochronology of post-occipital osteoderms for age validation of Australian freshwater crocodiles (Crocodylus johnstoni). Marine and Freshwater Research 48, 343–351.
| Crossref | GoogleScholarGoogle Scholar | von Bertalanffy L. (1960). Principles and theory of growth. In ‘Fundamental Aspects of Normal and Malignant Growth’. (Ed. W. W. Nowinski.) pp. 237–259. (Elsevier: Amsterdam.)

Webb G. J. W., and Manolis S. C. (1989). ‘Crocodiles of Australia.’ (Reed Books: Frenchs Forest, NSW.)

Webb, G. J. W. , and Smith, A. M. A. (1984). Sex ratio and survivorship in the Australian freshwater crocodile, Crocodylus johnstoni. Symposia of the Zoological Society of London 52, 319–355.


Webb, G. J. W. , Messel, H. , Crawford, J. , and Yerbury, M. J. (1978). Growth rates of Crocodylus porosus (Reptilia: Crocodilia) from Arnhem Land, Northern Australia. Australian Wildlife Research 5, 385–399.
| Crossref | GoogleScholarGoogle Scholar |

Webb, G. J. W. , Buckworth, R. , and Manolis, S. C. (1983). Crocodylus johnstoni in the McKinlay River area, NT. III. Growth, movement, and the population age structure. Australian Wildlife Research 10, 383–401.
| Crossref | GoogleScholarGoogle Scholar |

Wilkinson, P. M. , and Rhodes, W. E. (1997). Growth rates of American alligators in coastal South Carolina. The Journal of Wildlife Management 61, 397–402.