The distribution and abundance of the estuarine crocodile, Crocodylus porosus, in Queensland
Mark A. Read A , Jeffrey D. Miller A , Ian P. Bell B and Adam Felton B
+ Author Affiliations
- Author Affiliations
A Queensland Parks and Wildlife Service, PO Box 2066, Cairns, Qld 4870, Australia.
B Queensland Parks and Wildlife Service, PO Box 5597, Townsville, Qld 4810, Australia.
Wildlife Research 31(5) 527-534 https://doi.org/10.1071/WR02025
Submitted: 15 April 2002 Accepted: 3 March 2004 Published: 13 December 2004
Abstract
A total of 6444 Crocodylus porosus (4303 non-hatchlings and 2141 hatchlings) were recorded during 196 vessel-based surveys of 103 waterways to determine the distribution and abundance of Crocodylus porosus in Queensland. The surveys, conducted from January 1994 to December 2000, covered 4174.3 km of waterway. Population structure was biased towards immature crocodiles, with 91% of all animals sighted being less than the minimum breeding size for individuals in the Northern Territory. The mean relative density of non-hatchling C. porosus was highest in waterways of north-western Cape York Peninsula and Lakefield National Park, and lowest for waterways along the populated east coast of Queensland. The highest numbers of hatchlings were recorded from waterways of north-western Cape York Peninsula, where nearly 74% of all hatchlings were recorded during the seven-year survey period. The C. porosus population in northern Queensland appears to be undergoing a limited recovery, with marginal increases in the mean relative density of non-hatchlings in seven of the eight crocodile biogeographic regions. On the basis of the distribution and abundance of hatchling and non-hatchling crocodiles, the north-western Cape York Peninsula region contains the best habitat for C. porosus in Queensland, particularly in the Wenlock River and Tentpole Creek area.
Acknowledgments
The Queensland Environmental Protection Agency provided funding and infrastructure support to conduct research and monitoring on C. porosus in Queensland over the period January 1994 to December 2000. Many Departmental staff and volunteers donated their time and energy to make these surveys possible, with special mention to Dean Brake, Mark Burnham, Wayne Coleman, Mike Delaney, Dr Nancy FitzSimmons, Dr Chris Kofron, Philip Koloi and Rusty Smith. Drafts of this manuscript were reviewed by Dr Kirstin Dobbs, Professor Gordon Grigg and Dr Martin Cohen.
References
Bayliss
P.
(1987). Survey methods and monitoring within crocodile management programs. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 157–175. (Surrey Beatty & the Conservation Commission of the Northern Territory: Sydney.)
Cogger
H. G.
(1992). ‘Reptiles and Amphibians of Australia.’ 5th edn. (Reed Books: Sydney.)
Cook
T.
,
Gillam
E.
,
Barker
R.
, and
Ward
G.
(1997). Recent population and housing trends in Queensland 1997. Queensland Department of Local Government and Planning, Brisbane.
Cott, H. B. (1961). Scientific results of an inquiry into the ecology and economic status of the Nile crocodile (Crocodylus niloticus) in Uganda and Northern Rhodesia. Transactions of the Zoological Society of London 29, 211–356.
Graham
A.
(1968). The Lake Rudolf crocodile (Crocodylus niloticus Laurenti) population. Report to the Kenya Game Department by Wildlife Services Limited.
Kofron, C. P. , and Smith, R. (2001). Status of Estuarine crocodiles in the populated east coast of northern Queensland. Memoirs of the Queensland Museum 46, 603–610.
Messel
H.
,
Vorlicek
G. C.
,
Wells
A. G.
,
Green
W. J.
,
Curtis
H. S.
,
Roff
C. R. R.
,
Weaver
C. M.
, and
Johnson
A.
(1981). South western Cape York Peninsula (Nassau, Staaten and Gilbert River systems and Duck Creek system) and northern Cape York Peninsula (Port Musgrave: Wenlock and Ducie River systems, Palm, Dulcie and Namaleta Creeks, Escape River). Monograph 16. In ‘Surveys of Tidal Waterways on Cape York Peninsula, Queensland, Australia and their Crocodile Populations’. (Pergamon Press: Sydney.)
Miller
J. D.
(1994). Crocodiles in Queensland: a brief review. In ‘Crocodiles. Proceedings of the 2nd Regional (Eastern Asia, Oceania, Australasia) Meeting of the Crocodile Specialist Group, IUCN – The World Conservation Union, Gland, Switzerland.’ (Government Printers, for the Conservation Commission of the Northern Territory: Darwin.)
Miller
J. D.
, and
Bell
I. P.
(1997). Crocodiles in the Great Barrier Reef World Heritage area. In ‘State of the Great Barrier Reef World Heritage Area Workshop. Proceedings of a Technical Workshop held in Townsville, Queensland, Australia, 27–29 November 1995’. (Eds D. Wachenfeld, J. Oliver and K. Davis.) pp. 248–255. (Great Barrier Reef Marine Park Authority: Townsville.)
QDEH (1995). Conservation and management of Crocodylus porosus in Queensland 1995–1997. Department of Environment and Heritage, Brisbane.
QFMA (1998). Queensland Gulf of Carpentaria Inshore Finfish Fishery. Draft Management Plan and Regulatory Impact Statement. Queensland Fisheries Management Authority, Brisbane.
Roff
C.
(1966). Crocodiles in Queensland. Division of Plant Industry Advisory Leaflet No. 883.
Stirrat, S. C. , Lawson, D. , Freeland, W. J. , and Morton, R. (2001). Monitoring Crocodylus porosus populations in the Northern Territory of Australia: a retrospective power analysis. Wildlife Research 28, 547–554.
| Crossref | GoogleScholarGoogle Scholar |
Taplin
L. E.
(1987). The management of crocodiles in Queensland, Australia. In ‘Wildlife Management: Crocodiles and Alligators’. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 129–140. (Surrey Beatty & the Conservation Commission of the Northern Territory: Sydney.)
Taplin
L. E.
(1990). The population status and management of estuarine crocodiles in Queensland – present situation and future prospects. In ‘Proceedings of the 9th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of IUCN – The World Conservation Union. Lae, Papua New Guinea, 1988’.
Webb
G. J. W.
, and
Manolis
S. C.
(1989). ‘Crocodiles of Australia.’ (Reed Books: Sydney.)
Webb, G. J. W. , and Messel, H. (1978). Movement and dispersal patterns of Crocodylus porosus in some rivers of Arnhem Land, Northern Australia. Australian Journal of Zoology 26, 1–27.
Webb
G. J. W.
,
Manolis
S. C.
,
Whitehead
P. J.
, and
Letts
G. A.
(1984). A proposal for the transfer of the Australian population of Crocodylus porosus Schneider (1801), from Appendix I to Appendix II of CITES. Conservation Commission of the Northern Territory, Technical Report No. 21.
Webb
G. J. W.
,
Whitehead
P. J.
, and
Manolis
S. C.
(1987). Crocodile management in the Northern Territory of Australia. In ‘Wildlife Management: Crocodiles and Alligators. (Eds G. J. W. Webb, S. C. Manolis and P. J. Whitehead.) pp. 107–124. (Surrey Beatty & the Conservation Commission of the Northern Territory: Sydney.)
Webb, G. J. W. , Hollis, G. J. , and Manolis, S. C. (1991). Feeding, growth and food conversion rates of wild juvenile saltwater crocodiles (Crocodylus porosus). Journal of Herpetology 25, 462–473.
Webb
G. J. W.
,
Manolis
S. C.
, and
Ottley
B.
(1994). Crocodile management and research in the Northern Territory: 1992–94. In ‘Crocodiles. Proceedings of the 12th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of IUCN – The World Conservation Union. Pattaya, 2–6 May 1994’. pp. 167–180. (IUCN: Gland, Switzerland.)
Webb
G. J. W.
,
Britton
A. R. C.
,
Manolis
S. C.
,
Ottley
B.
, and
Stirrat
S.
(2000). The recovery of Crocodylus porosus in the Northern Territory of Australia: 1971–1998. In ‘Crocodiles. Proceedings of the 15th Working Meeting of the Crocodile Specialist Group of the Species Survival Commission of IUCN – The World Conservation Union. Veredero, Cuba. January 2000’. (IUCN: Gland, Switzerland.)
