Grahame Webb

On the IUCN Red List the saltwater crocodile Crocodylus porosus is categorized globally as Least Concern, with national populations ranging from fully recovered to extinct. The saltwater crocodile population of the Southeast Asian island nation of Timor-Leste was severely depleted by colonial hunting but has recovered since independence in 2002. Du...

Management programs that successfully recovered wild saltwater crocodile ( Crocodylus porosus ) populations in the Northern Territory of Australia did so with an expanding commitment to maintaining public safety. One aspect of the program is the ongoing removal of resident and immigrant crocodiles within Darwin Harbor (since 1979), the main urban c...

Monitoring of the ecological and social, including economic aspects of uses of wild species is critical for sustainable use. Progress towards achieving the Sustainable Development Goals and the Aichi Biodiversity Targets is assessed using global indicators, however to date, there is not a comprehensive set of global indicators able to monitor statu...

Non‐crocodylian reptiles have hearts with a single ventricle, which is partially separated by a muscular ridge that provides some separation of blood flows. An exceptional situation exists in monitor lizards and pythons, where the ventricular left side generates a much higher systolic blood pressure than the right side, thus resembling mammals and...

Wild animals are captured or taken opportunistically, and the meat, body parts, and/or eggs are consumed for local subsistence or used for traditional purposes to some extent across most of the world, particularly in the tropics and subtropics. The consumption of aquatic animals is widespread, in some places has been sustained for millennia, and ca...

Non-crocodylian reptiles have hearts with a single ventricle, which is partially separated by a muscular ridge that provide some separation of blood flows. An exceptional situation exists in monitor lizards and pythons, where the ventricular left side generates a much higher systolic blood pressure than the right side, thus resembling mammals and b...

Landscape genetics commonly focusses on the effects of environmental resistance on animal dispersal patterns but there is an emerging focus on testing environmental effects on emigration and settlement choices. In this study, we used landscape genetics approaches to quantify dispersal patterns in the world’s largest crocodilian, the saltwater croco...

We report two cases of Cane Toads Rhinella marina being killed by Australasian Giant Centipedes Ethmostigmus rubripes in the Northern Territory. At 1730 h on 12 November 2020, a centipede was found attacking a subadult Cane Toad near Larrimah, Northern Territory. At 2015 h on 26 April 2005, near Humpty Doo, a centipede that was seized by a subadult...

Saltwater Crocodile Crocodylus porosus has most recently been assessed for The IUCN Red List of Threatened Species in 2020. Crocodylus porosus is listed as Least Concern.

Large‐bodied predators are well represented among the world's threatened and endangered species. A significant body of literature shows that in terrestrial and marine ecosystems large predators can play important roles in ecosystem structure and functioning. By contrast, the ecological roles and importance of large predators within freshwater ecosy...

ContextThe population of saltwater crocodiles, Crocodylus porosus, in the Northern Territory, Australia, has been recovering from a period of intensive, unregulated harvest (1945–1971) since protection in 1971. Consequently, the management goal is shifting from restoring a seriously depleted population to managing an abundant population through con...

Translocated saltwater crocodiles (Crocodylus porosus) in the Northern Territory (NT) of Australia often return to their original capture sites, which complicates management interventions aimed at reducing human-crocodile conflict. We examined the spatial events implicated in this homing ability, using ARGOS satellite tracking devices. Five large m...

Cultural beliefs based on Timor-Leste´s creation myth "Lafaek Diak-The Good Crocodile" are anchored in the East Timorese traditional belief system lulik and involve worship of the widely distributed, but dangerous , saltwater crocodile (Crocodylus porosus). The wild saltwater crocodile population and rate of fatal attacks on people are both increas...

Article impact statement: Wallach et al.’s framing of compassionate conservation is flawed and impractical and could be dangerous for people, wildlife, and ecosystems.

In northern Australia and nearby Timor‐Leste, saltwater crocodile (Crocodylus porosus) populations were seriously depleted historically but recovered rapidly after protection: 1969–1974 in northern Australia, and 2000–2005 in Timor‐Leste. In both places, recovery caused increased rates of human‐crocodile conflict (HCC). Within northern Australia, t...

Hypoxia within the oviducts maintains embryonic arrest in turtles at the pre-ovipositional stage, which expands the timeframe over which nesting can occur without compromising embryo survival. The arrest can be extended post-oviposition through incubation of eggs in hypoxia. We determined whether crocodilian embryos have this same capacity. We also...

Sustainable commercial use of native wildlife is an alternative economic means of land use by Indigenous people in remote rural areas. This situation applies within large tracts of land owned by Indigenous people across northern Australia. The commercial use of saltwater crocodiles Crocodylus porosus is a growing industry in Australia's Northern Te...

Due in part to their large size, aggressive temperament, and difficulty in handling, there are few physiological studies of adult crocodilians in the literature. As a result, studies comparing individuals across an ontogenetic series and comparisons among species are also lacking. We addressed this gap in knowledge by measuring standard metabolic r...

Raw data used to calculate standard metabolism in three species of crocodilians. (XLSX)

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 de...

The purpose of this study was to examine the effect of density on growth rate, agonistic behaviour, activity and use of space by hatchling C. porosus in captivity. Hatchling C. porosus were raised in identical enclosures (1.5 m²) at different densities (3.3, 6.7, 13.3 and 20.0 hatchlings/m²; or 0.30, 0.15, 0.08 and 0.05 m²/hatchling respectively)....

Since 2006, 3 new disease syndromes have emerged in farmed saltwater crocodiles (Crocodylus porosus) in the Northern Territory of Australia. We describe the syndromes through a retrospective study of laboratory findings from 187 diagnostic cases submitted to Berrimah Veterinary Laboratories between 2005 and 2014. The first syndrome was characterize...

Key points • Under Colombian law, the sale of game to cover basic needs (e.g. housing, health, education) or to buy other food items is not allowed, since this is considered commercial hunting and does not fall under provisions allowing for subsistence bushmeat hunting. • Law 611 (2000) opened the path to legal commercial use of wildlife. In practi...

Invasive predators can cause population declines in native prey species, but empirical evidence linking declines of native predators to invasive prey is relatively rare. Here, we document declines in an Australian freshwater crocodile Crocodylus johnstoni population following invasion of a toxic prey species, the cane toad Rhinella marina. Thirty-f...

Much of what is known about crocodilian nutrition and growth has come from animals propagated in captivity, but captive animals from the families Crocodilidae and Alligatoridae respond differently to similar diets. Since there are few comparative studies of crocodilian digestive physiology to help explain these differences, we investigated young Al...

In northern Australia Crocodylus porosus nest between November and March, i.e. during the wet season. Mean distance between nests and permanent water was 7.8 m. Nests adjacent to more saline, lower reaches of rivers were in freshwater swamps, whereas further upstream they were beside the river. The nests are mounds, with mean dimensions: 53 cm high...

Background/Question/Methods Invasive species are a global conservation concern. While many invasive predators cause population declines in native prey species, empirical evidence linking declines of native predators to invasive prey species is comparatively rare. We used 35 years of standardized spotlight surveys in northern Australia to investig...

Hatchling fitness in crocodilians is affected by "runtism" or failure to thrive syndrome (FTT) in captivity. In this study, 300 hatchling C. porosus, artificially incubated at 32°C for most of their embryonic development, were raised in semi-controlled conditions, with growth criteria derived for the early detection of FTT (within 24 days). Body ma...

Interspecific adult bite forces for all extant crocodylian species are now known. However, how bite forces scale during ontogeny across the clade has yet to be studied. Here we test the hypotheses that extant crocodylians share positively allometric and statistically comparable developmental scaling coefficients for maximal bite-force capacity rela...

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds), and occurred between 1600-2200 h in open water. The nature and exte...

We examined agonistic behaviour in hatchling Australian freshwater crocodiles (Crocodylus johnstoni) at 2 weeks, 13 weeks, and 50 weeks after hatching, and between C. johnstoni and saltwater crocodiles (Crocodylus porosus) at 40-50 weeks of age. Among C. johnstoni, agonistic interactions (15-23 s duration) were well established by two weeks old and...

Detailed observations on groups of captive saltwater crocodile (Crocodylus porosus) hatchlings revealed sporadic periods of intense agonistic interactions, with 16 highly distinctive behaviours, in the morning (06:00 08:00Ah) and evening (17:00 20:00h) in shallow water. Ontogenetic changes in agonistic behaviour were quantified by examining 18 diff...

Standard metabolic rate (SMR, ml O(2) min(-1)) of captive Crocodylus porosus at 30 °C scales with body mass (kg) according to the equation, SMR = 1.01 M(0.829), in animals ranging in body mass of 3.3 orders of magnitude (0.19-389 kg). The exponent is significantly higher than 0.75, so does not conform to quarter-power scaling theory, but rather is...

Colombia uses a closed-cycle captive breeding program for producing Caiman crocodilus (mostly C. c. fuscus) skins for export. Skin size limits are used as a regulatory measure to exclude illegal wild-caught adults entering legal trade. However, the size limits employed were not well defined by morphological endpoints, and the degree of shrinkage be...

Crocodilians have dominated predatory niches at the water-land interface for over 85 million years. Like their ancestors, living species show substantial variation in their jaw proportions, dental form and body size. These differences are often assumed to reflect anatomical specialization related to feeding and niche occupation, but quantified data...

Saltwater crocodiles (Crocodylus porosus) in the Northern Territory of Australia were protected in 1971, after a severe population decline resulting from 26 yr of intense commercial hunting. By that time wild saltwater crocodiles were rarely sighted anywhere and they were commercially extinct in areas where they had once been abundant. Standardized...

A publication from the Think Tank for Kangaroos (THINKK) in the Institute of Sustainable Futures at the University of Technology Sydney evaluates the idea that eating wild harvested kangaroo meat is environmentally beneficial, compared to other meats produced on rangelands (Ben-Ami et al. 2010). It finds in the negative. The report purports to be a...

We measured standard metabolic rate (SMR) and the metabolic response to feeding in the Australian crocodiles, Crocodylus porosus and C. johnsoni. Both species exhibit a response that is characterised by rapidly increasing metabolism that peaks within 24h of feeding, a postfeeding metabolic peak (peak V̇O2) of 1.4-2.0 times SMR, and a return to base...

Ten Curettochelys insculptu nests from the Daly River, in the Northern Territory of Australia, are described. Eggs were in sand banks beside the river and were laid during August and September, in the dry season. Mean clutch size was 12.7±3.3 eggs (SD). Eggs are hard-shelled and spherical (mean egg diameter 38.7 k0.13 mm) and weigh 33.7±3.5 g. Embr...

The catalytic activity of phospholipase A2 (PLA2) was measured in serum samples from 32 crocodiles in Thailand and Australia by a method using 14C-oleic acid-labelled autoclaved Escherichia coli membranes as a substrate. The highest PLA2 activity was measured in the serum of Crocodylus siamensis (n = 9, mean ± SD), 13.3 ± 3.1 U/l followed by hybrid...

Since 1963 the International Union for Conservation of Nature (IUCN) Red List has provided the world with a credible and effective call to action for preventing species extinction. However, the criteria for assigning categories of threat (e.g. 'critically endangered,' 'endangered,' 'vulnerable'), particularly the 'decline criteria' (Criteria A), of...

Tomistoma schlegelii is a threatened crocodilian whose current range is restricted to Sumatra, Borneo (Kalimantan and Sarawak) and Peninsular Malaysia. During surveys undertaken in eastern Sumatra in 1995–1996, 15 T. schlegelii nests were located in peat swamp forest along a single tributary, the Merang River. No other areas with equivalent nest de...

We investigated the effects of incubation temperature (29°C, 31°C, and 33°C) on total length (TL) and body mass (BM) of Caiman latirostris, a crocodilian with temperature-dependent sex determination (TSD), at hatching (N = 180) and in a sample of hatchlings (N = 40) after one year of raising. Size at hatching was strongly clutch-specific. Animals i...

A total of 3156 scale row records, comprising 1739 full-sibling records from 30 families from Janamba Croc Farm (NT, Australia) and 1417 parent-offspring records from 19 families from Wildlife Management International, Pty Ltd (NT, Australia), collected at each facility using a different method, were analysed using ASReml. The full-sibling heritabi...

Crocodilians represent one of the oldest constant animal lineages on the planet, in no small part due to their formidable array of predatory adaptations. As both human and crocodilian populations expand, they increasingly encroach on each others' territories, bringing morbidity and mortality to both populations. In this article, the medical and her...

1.1. At COP12 there are five proposals to list sharks and other commercial fisheries species on Appendix II of CITES, in accordance with Article II of the Convention. 1.2. In terms of compliance with Article II of the Convention, none of the five species have global populations demonstrated at being of risk of biological extinction, despite concern...

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The proposition that wildlife conservation can sometimes be enhanced through allowing and even promoting the harvesting of wildlife is a sensitive issue. For the last 30 years, conservation has tended to focus on protecting rather than using wildlife. Yet conservation through sustainable use (CSU) is now a mainstream conservation strategy, and rese...

The IUCN Red List of Threatened Animals is an important conservation tool, but the accuracy of predictions about risks of global extinction within 10 years or three generations is difficult to test objectively. In this study, we compare IUCN predictions with the results of attempts to derive realistic scenarios that could lead to the global extinct...

1.1. At the next Conference of the Parties to CITES (COP11. Nairobi, Kenya; April 2000) three globally distributed shark species have been proposed for listing on the Appendices pursuant to Resolution Conf. 9.24: Great White shark ( Carcharodon carcharias ) for Appendix I; Whale shark ( Rhincodon typus ) for Appendix II; and Basking shark ( Cetorhi...

Since the 1500s hawksbill turtles (Eretmochelys imbricata) have been harvested for food and tortoiseshell trade in Cuban waters. Between 1935 and 1994 an estimated 168,781 animals (8600 metric tons live body weight) were harvested. Starting in 1968 the harvest was managed as a commercial fishery in four fishing Zones (A-D) with the goal of sustaini...

In order to understand Aboriginal wildlife harvesting in the Top End of the Northern Territory of Australia a series of studies was initiated by Wildlife Management International Pty Limited. The study reported here took place at Momega in north-central Arnhem Land, mostly in 1997. It followed an earlier examination of wildlife use at Momega by Alt...

To examine whether sub-optimal temperature induced stress and immunosuppression in farmed saltwater crocodile (Crocodylus porosus) hatchlings. A clinico-pathological study. A total of 140 hatchlings were used. Body weight and length, plasma corticosterone and immunoglobulin concentrations and total and differential white blood cell counts were meas...