Some Physiological Consequences of Estivation by Freshwater Crocodiles, Crocodylus johnstoni

1996 ◽  
Vol 30 (1) ◽  
pp. 1 ◽  
Author(s):  
Keith Christian ◽  
Brian Green ◽  
Rod Kennett
Keyword(s):  
Crocodylus Johnstoni

Crocodylus johnstoni and C. porosus Coexisting in a Tidal River

1983 ◽  
Vol 10 (3) ◽  
pp. 639 ◽  
Author(s):  
GJW Webb ◽  
SC Manolis ◽  
GC .Sack
Keyword(s):  
Competitive Exclusion ◽  
Dry Season ◽  
Tidal River ◽  
Main Stream ◽  
Wet Season ◽  
Seasonal Movements ◽  
Crocodylus Johnstoni ◽  
Seasonal Factors

A 52.5-km section of the Adelaide River, N.T. (12�13'S., 131�13'E.). was spotlight-surveyed 20 times between June 1979 and September 1981. C, johnstoni (15.3 � 9.2 sighted per survey) were less abundant than C. porosus (137.6 � 36.5 sighted per survey), and were mainly in the upstream 20 km of the survey route (96% of C. johnstoni sightings); here considered a zone of syntopy within the survey route. C. johnstoni congregate in the main stream during the dry season and disperse from it during the wet season, which parallels similar seasonal movements to and from dry-season refuges in non-tidal areas lacking C. porosus. As the dry season progresses, C. johnstoni are located further and further upstream, and this movement (or loss ofanimals) appears unrelated to changes in salinity. Numbers of C.johnstoni within the zone of syntopy are negatively correlated with numbers of C. porosus (r*2 = 0.50, P=0.005). and competitive exclusion may be occurring. Independent of seasonal factors, numbers of C. johnstoni within the zone of syntopy declined with consecutive month (1979-81: r*2=0.47, P= O.004), whereas numbers ofthe more recently protected C, porosus increased (r2 = 0.48, P= 0,006). The location of the syntopic zone was unchanged.

Effect of Incubation Temperature on Development of Crocodylus johnstoni Embryos

1990 ◽  
Vol 63 (5) ◽  
pp. 949-964 ◽  
Author(s):  
P. J. Whitehead ◽  
G. J. W. Webb ◽  
R. S. Seymour
Keyword(s):  
Incubation Temperature ◽  
Crocodylus Johnstoni

Crocodylus johnstoni in the McKinlay River Area N. T, IV.* A Demonstration of Homing

1983 ◽  
Vol 10 (2) ◽  
pp. 403 ◽  
Author(s):  
GJW Webb ◽  
SC Manolis ◽  
R Buckworth
Keyword(s):  
Male And Female ◽  
Wild Male ◽  
Crocodylus Johnstoni ◽  
Capture Site ◽  
A Site

Of 17 wild male and female C, johnstoni which were released at a site 30 km upstream of their capture site, eight were caught again, seven at the site of capture and one between the two sites; they demonstrated a distinct homing ability.

Morphometric analysis of the Australian freshwater crocodile (Crocodylus johnstoni)

2017 ◽  
Vol 65 (2) ◽  
pp. 97 ◽  
Author(s):  
Glenn P. Edwards ◽  
Grahame J. Webb ◽  
S. Charlie Manolis ◽  
Alex Mazanov
Keyword(s):  
Morphometric Analysis ◽  
Body Measurements ◽  
Body Parts ◽  
Allometric Growth ◽  
Relative Growth ◽  
Crocodylus Johnstoni ◽  
Arnhem Land ◽  
Freshwater Crocodile ◽  
Crocodylus Porosus ◽  
Australian Freshwater

We conducted a morphometric analysis of 279 Crocodylus johnstoni, using specimens from the McKinlay River (n = 265) and Arnhem Land (n = 14), to meet the management need for predicting body size of C. johnstoni from isolated body parts. The results also allow reconstruction of C. johnstoni dimensions for comparison with other crocodilian species. We detected sexual dimorphism in some body measurements from the McKinlay River, and geographic variation in the morphology of McKinlay River and Arnhem Land populations, but differences were slight. There is pronounced allometric growth in C. johnstoni in the immediate post-hatching phase, largely due to elongation of the snout after exiting the confines of the egg. We compared the size, shape and relative growth of C. johnstoni with that of other crocodilian species for which equivalent data are available, but particularly the other Australian crocodile, Crocodylus porosus. C. porosus has a proportionately longer tail and a shorter but wider snout than C. johnstoni, and we discuss possible ecological correlates of these and other differences.

Movements and Home Ranges of Crocodylus johnstoni in the Lynd River, Queensland

1997 ◽  
Vol 24 (4) ◽  
pp. 379 ◽  
Author(s):  
A. D. Tucker ◽  
C. J. Limpus ◽  
H. I. McCallum ◽  
K. R. McDonald
Keyword(s):  
Field Trips ◽  
Home Ranges ◽  
Adult Males ◽  
Dominance Hierarchies ◽  
Breeding Sites ◽  
Crocodylus Johnstoni ◽  
Upstream Direction ◽  
A Minor ◽  
Australian Freshwater ◽  
Local Dominance

Movements of Australian freshwater crocodiles, Crocodylus johnstoni, were examined by a mark–recapture study spanning 20 years in the Lynd River, Queensland. After adjustment for detection bias, there was a minor upstream direction to movements. Seasonal changes of location were not evident from field trips taken only twice yearly. Annual movements averaged less than 1 km except for those of pubescent males, which appeared to be nomadic. Creche dispersal was randomly directed but associated with a threshold in mass/length ratio. On average, males were found further from previous capture sites than were females. Adults of both sexes moved shorter distances than did immature crocodiles with a clear reduction in movements occurring as mass/length ratios approached 0·17 kg per cm snout–vent length. Reduced movement at that general size ratio probably indicated the onset of territoriality associated with maturity. Females usually remained near breeding sites even in years when they did not breed. Nomadic tendencies of pubescent males are probably associated with unsuccessful attempts at entering local dominance hierarchies. Linear home ranges were estimated to be 1·5–1·9 km for immature animals, 1·2 km for pubescent females, 30·3 km for pubescent males, 0·6 km for mature females and 1·6 km for adult males.

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