Using Environmental DNA to search for Crocodiles in Madagascar.

The world is currently suffering from multiple interconnected environmental crises, including a rapid loss of biodiversity in many parts of the world. Madagascar, a global biodiversity hotspot with a large number of species found nowhere else, is considered to be particularly at risk, due to unprecedented rates of habitat loss. However, tracking this loss is challenging, as monitoring species loss involves a large amount of labour intensive work by specialist taxonomic experts, often involving access to expensive equipment.

Environmental DNA offers a potential way to reduce this workload, allowing for monitoring to be carried out by non-specialist staff collecting samples of sediment, water or even air. Since such methods to not require direct observation of threatened species, they are far less environmentally intrusive.

Nile Crocodiles, Crocodylus niloticus, were persecuted across their range by hunters seeking their skins, as well as harvesting of their eggs, until the mid-twentieth century. Since this time, the population has recovered in many parts of Africa due to conservation efforts. In Madagascar, the species is monitored by the Malagasy Crocodile Management Unit, which aims not just to establish the recovery of the species, but to minimise Human-Crocodile conflicts by helping people and livestock to avoid potentially lethal Crocodile encounters.

Previous work using environmental DNA has succeeded in detecting Crocodiles kept under laboratory conditions, but struggled to locate them in the wild, although methods such as water sweeps have proven more successful.

In a paper published in the journal Biodiversity and Conservation on 23 October 2025, Mai Fahmy of the Department of Undergraduate Biololgy at Stony Brook University, and the Division of Invertebrate Zoology at the American Museum of Natural History, Soja Manjakamanana Zafimanaoela of the Université d’Antananarivo, Njakamamapiadana Mamenofahasoavana Rinah and Jerison William Ranaivosolo of Stony Brook University's Centre ValBio in Madagascar, Noel Rowe of Primate Conservation Inc., Patricia Wright, also of the Centre ValBio, and of the Department of Anthropology and Interdepartmental Doctoral Program in Anthropological Sciences at Stony Brook University, and Evon Hekkala, also of the Department of Undergraduate Biololgy at Stony Brook University, and the Division of Vertebrate Zoology at the American Museum of Natural History, present the results of a study, in which they attempted to detect Crocodiles in Madagascar using sediment samples as well as specialist environmental DNA filters and Coffee filters, in an attempt to find a cost-effective method of detecting the Animals. 

Anivorano lake in northern Madagascar, traditionally held to be sacred. Here the local population periodically sacrifices Zebu Cattle to the Crocodiles, which are believed to contain the spirits of pas chiefs, in a ceremony that also involves dancing and singing. On such occasions, the Crocodiles are fed beef from a beach about 30 m long near a sacred tree, and subsequently typically remain in the area for about eight hours, basking on the beach or in the water.

Map of collection localities across Madagascar. TSP, Tsimanampetsotse National Park. Fahmy et al. (2025).

Fahmy et al. collected sediment from a belly print left on the beach by a Crocodile, Crocodile faecal matter, and water from an area close to where Crocodiles were basking. The water and faecal samples were subsequently passed through Coffee filters, which were retained. 

At the Ankarana Special Reserve, also in northern Madagascar, Fahmy et al. collected sediment samples from the river mouth leading into the Ankarana Cave System, with two samples collected from the footprints of Crocodiles, one adult and one juvenile. Water was also collected from a flooded cave entrance, and again filtered through a coffee filter.

Water samples were also collected from the Ihosy, Mananantanana, and Matitanana rivers in central and southeastern Madagascar, and filtered through specialist environmental DNA filters. These are wide, fast flowing rivers, used exclusively by the local population for transport, hygiene, and watering livestock. Samples were taken following sightings of Crocodiles, and only with the explicit permission of local communities.

Nile Crocodile, Crocodylus niloticus, spotted in the Matitanana River while sampling. Mai Fahmy in Fahmy et al. (2025).

Finally, four samples were collected from a submerged cave located in Tsimanampesotse National Park in southwest Madagascar. Nile Crocodiles have never been observed in these caves, although they are known to inhabit the nearby Onalahy River. The caves were, however, utilised by the extinct Madagascan Horned Crocodile, Voay robustus, which is thought to have died out about 1250 years ago. These samples were again filtered through Coffee filters. A sediment sample was also collected from beneath a subfossil Horned Crocodile in the caves.

A total of seventeen samples were collected and processed. Four of the samples were subsequently discarded because they were found to contain only Human DNA, and one because it contained Sheep DNA. In the remaining samples, the greatest number of species were recovered from the Coffee filter samples; although this did not represent the greatest diversity. Sediment and environmental DNA samples produced equal numbers of species, although greater overall diversity was recorded in the sediment samples. DNA associated with members of the Family Podicipedidae (Grebes) was recovered exclusively in the environmental DNA filters, while DNA associates with the Family Naididae (Tubifex Worms) was recovered exclusively from sediment samples.

Crocodile DNA was recovered from both sediment samples and Coffee filters, but not from specialist environmental DNA filters. However, Fahmy et al. do not suggest that this is because Coffee filters are superior to environmental DNA filters, as the later were only used to filter water samples from fast flowing rivers, where recovering Crocodile DNA is known to be difficult. 

Zebu Cattle drinking from Matitanana River. Mia Fahmy in Fahmy et al. (2025).

Three samples yielded Crocodile DNA, all from Lake Anivorano. These included the sediment sample taken from the Crocodile belly print, and the Coffee filters through which the faecal sample and water from close to Crocodiles basking in the lake were filtered. The analysis recovered these as belonging to the genus Crocodylus, and most likely as coming from Nile Crocodiles, Crocodylus niloticus, with a lower chance of coming from Orinoco Crocodiles, Crocodylus intermedius, of American Crocodiles, Crocodylus acutus, neither of which are found in Madagascar. 

The three most abundant species in the results were Cattle, Bos taurus, Chickens, Gallus gallus, and Domestic Pigs, Sus scrofa. Also detected were Ring-tailed Lemur, Lemur catta, and an unknown species of Grebe (Podicepepidae). This could not be identified to species level, although several Grebes are known from Madagascar, including the Little Grebe, Tachybaptus ruficollis, and the Madagascar Grebe, Tachybaptus pelzelnii. Interestingly, the Madagascar Grebe does not have any genetic material recorded in the GenBank database, against which the samples were compared.

The method developed by Fahmy et al. did not establish the presence of Crocodiles in anywhere they were not known to occur, but did establish that it was possible to detect Crocodiles using environmental DNA in Madagascar, and that it was possible to use Coffee filters as a means of recovering environmental DNA, a much cheaper option than specialist filters.

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Investigating Crocodile attacks around Roviana Lagoon, New Georgia, the Solomon Islands.

Saltwater Crocodiles, Crocodylus porosus, are found in coastal environments in the Asia-Pacific region from the Bay of Bengal, throughout Southeast Asia and New Guinea, to northern Australia, and as far east as the Solomon Islands. Unlike other Crocodile species, they are not currently considered to be threatened, being classified as of Least Concern under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. However, this assessment is essentially dependent on good relations between Human and Crocodile populations; Saltwater Crocodiles will attack Humans and livestock, causing injuries and deaths, as well as less obvious economic damage by excluding Humans from areas where they become dangerous. This in turn can lead to retaliatory actions by Humans, removing troublesome Crocodiles, or sometimes whole populations, from areas where they are seen as harmful. 

Saltwater Crocodiles feed in tidal rivers and creeks, freshwater lakes and Mangrove forests, and will occasionally forage on Coral reefs. While they cross open sea to seek new territory, they do not usually hunt or feed there. Female Saltwater Crocodiles can reach about 3 m in length, and can weigh as much as 150 kg, but the largest males can reach more than 6 m in length and weigh more than 1000 kg. Males will try to defend a territory and the females within it, chasing away smaller males, who then go on to look for territories of their own, which can lead to changes in the social structure and behaviour of Crocodile groups.

In a paper published in the journal Orynx on 22 January 2024, Shankar Aswani of Rhodes University and Joshua Matazima of the University of Queensland present the results of a study of negative Human-Crocodile interactions around Roviana Lagoon on the island of New Georgia in the Solomon Islands.

A previous study examined Human-Crocodile interactions across the Solomon Islands over the period 1998-2017. This study identified 225 Crocodile attacks across the islands, with 83 of these being fatal, including 31 on children. Aswani and Matazima's study concentrates on a much smaller area, and is aimed at understanding Human-Crocodile interactions in a specific, localised environment with a view to developing specific policies for that location, something which it is difficult to achieve from wider scale national surveys.

Aswani and Matazima's study concentrated on four villages, Dunde, Baraulu, Nusa Hope, and Kozou, located on the 700 km² Roviana Lagoon, on the southwest of New Georgia island. Each village has a population of between 50 and 300 people. Twenty three men and thirty seven women from sixty households across the four villages were interviewed by three locally hired assistants, in the local Roviana language. Twenty of the interviewees reported that a member of their household being attacked by a Crocodile between 2000 and 2020, four in Dunde, seven in Baraulu, five in Nusa Hope and four in Kozou.

Locations of the four villages (Dunde, Baraulu, Nusa Hope and Kozou) in which residents were interviewed regarding incidents with Saltwater Srocodiles, Crocodylus porosus, in  Roviana Lagoon, New Georgia Group, western Solomon Islands, during 2000-2020. Aswani & Matazima (2024).

A total of twenty attacks were recalled, of which two were fatal. Ten of the recalled incidents happened in the evening, eight in the afternoon, and two in the morning. Sixteen victims were female, and four were male; one woman and one man were killed during the study period. Two were under twenty years of age, eight were between 20 and 39, two were 40-59, and eight were over sixty years of age. The majority of the victims were attacked while collecting shellfish along the sea shore and in Mangrove forests. Ten of the victims were attacked when the water was murky, with the other ten attacked when the water was clear. No retaliatory attacks were made against Crocodiles be the people of the area.

The pattern of attacks recorded in Roviana Lagoon were quite different to that recorded in the Solomon Islands-wide survey, although it may be similar to other localised areas within the nation. Across the Solomons, the majority of the victims were male, attacked at night while fishing, while in Roviana Lagoon the majority of the victims were female, attacked in the afternoon or early evening while gathering shellfish. Clearly, any system developed to minimize the number of Crocodile attacks based upon the national statistics would have little impact at Roviana Lagoon, since such a plan would likely concentrate on protecting men involved in night-fishing, an activity not practiced in Roviana Lagoon. Even a female specific plan developed from national statistics would be unlikely to be helpful, as across the Solomon Islands the majority of women are attacked while washing clothes.

Shellfish gathering, both for sustenance and sale, is an important activity to the women of Roviana Lagoon, but clearly leaves them vulnerable to attacks by Crocodiles. This activity is carried out almost exclusively by women, although they are frequently accompanied by children of both sexes. Most of the attacks happened in late afternoon or early evening, and water clarity did not appear to be a factor, possibly because the low sun shining onto clear water can make submerged Crocodiles just as hard to spot as the water being cloudy. 

Aswani and Matazima recommend that in order to minimise the number of Crocodile attacks, the women of Roviana Lagoon avoid collecting shellfish in the late afternoon and evening as much as possible, and that where this cannot be avoided, always forage in groups at this time of day, which will both improve the chances of spotting Crocodiles before attacks occur, and of rescuing any victims should attacks occur. They further recommend that future studies of Crocodile attacks focus on much narrower geographic areas when the purpose is to develop strategies to minimise attacks.

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Gavialis gangeticus: Gharials on the upper Ghaghara River, India.

Gharials, Gavialis gangeticus, are freshwater Crocodilians found only on the Indian Subcontinent. Modification of river systems by damming and water extraction has fragmented the Gharial population into a series of isolated subpopulations, leading to a steady decline in their available habitat and total number of Animals, for which reason Gharails are now considered to be Critically Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species.

In 1976 the construction of a irrigation barrage on the Girwa–Kaudiyala Rivers led to the isolation of a population of Gharials on the Girwa River within the Katerniaghat Wildlife Sanctuary in Uttar Pradesh, with the species disappearing from the Karnali River upstream of the sanctuary and the Ghaghara River downstream. The Girwa River population is monitored by the Katerniaghat Wildlife Division, with 72 individuals and 36 nests recorded in February 2020, but there is no regular monitoring of the Ghaghara River. The number of juvenile Gharials reaching adulthood in the Girwa River is surprisingly low, and it has been suggested that hatchlings might be being swept into the Ghaghara River when the gates of the barrage are opened in the monsoon season.

In a paper published in the journal Oryx on 22 December 2023, Gaurav Vashistha of Sri Guru Nanak Dev Khalsa College at the University of Delhi, and the Gharial Conservation Programme, Vivek Ranjan of the Wildlife Institute of India, Devvrat Singh and Shantanu Ugemuge, also of the Gharial Conservation Programme, Akash Deep Badhawan of the Katerniaghat Wildlife Division, and Pulkit Gupta, again of the Gharial Conservation Programme, present the results of a survey of the upper stretch of the Ghaghara River, from the Girijapuri Barrage in Katerniaghat Wildlife Sanctuary downstream to Chahlari Ghat.

Locations where Gharials, Gavialis gangeticus, were sighted during a survey of a 100 km stretch of the Ghaghara River, India, from Girijapuri Barrage to Chahlari Ghat. Vashistha et al. (2023).

The Ghaghara River carries 21% of the total volume of water entering the Ganga, making it the river's largest tributary. Water flow within the Ghaghara is controlled by the Girijapuri Barrage on the Girwa River and the Sharda Nagar Barrage on the Sharda River, both of which are opened three times a year. The opening of the barrages allows large quantities of sediment to be carried downstream, allowing the formation of braids in the Ghaghara River. Vashistha et al. surveyed a 100 km section of the river by boat from the Girijapuri Barrage to Chahlari Ghat between 9.00 am and 5.00 pm on 26 and 27 February 2023, travelling 50 km each day. 

Observed Gharials were recorded, and placed in four size classes based upon their estimated lengths, these being yearlings under 1 m in length, juveniles 1-2 m in length, subadults 2-3 m in length, and adults more than 3 m in length. Vashistha et al. also searched for spoor marks on the riverbanks.

Vashistha et al. observed 84 Gharials at 29 locations, the majority of which were young Animals less than 2 m in length, including 16 yearlings presumed to have hatched in 2022. No adult males (which can be identified by the presence of a nasal protuberance called a 'ghara') were observed, although three adult females had bulging abdomens, which is a possible sign of pregnancy. No trace was found of 40 tagged Gharials released into the river by the Uttar Pradesh Forest Department in 2020, although a 2021 survey of the lower part of the river observed eight of these Animals.

A basking female Gharial, Gavialis gangeticus, on the Ghaghara River bank, with a bulging abdomen suggesting she could be pregnant. Vashistha et al. (2023).

Based upon the results of their survey and the survey of the lower part of the river carried out the year before, Vashistha et al. estimate that the Ghaghara River has a population of 258. This is almost four times as high as the estimated population of the Girwa River in Katerniaghat Wildlife Sanctuary. Vashistha et al. believe that this confirms the hypothesis that Gharials are dispersing from the Girwa River into the Ghaghara when the barrage is open. The presence of three females with bulging abdomens suggests that they are breeding on the Ghaghara River, although this cannot be proved. Eight adult males were spotted during the survey of the lower river, and females are known to move some distance between seasons.

There are long stretches of undisturbed, free-flowing water on the Ghaghara River, with plenty of sandy banks suitable for nesting. The river is known to be a sink for Animals dispersing downstream from the Girwa and Kaudiyala rivers, and as well as a population of Gharials, is home to Endangered Ganges River Dolphins, Platanista gangetica, Vulnerable Indian Flapshell Turtles, Lissemys punctata, Indian Softshell Turtles, Nilssonia gangetica, and Indian Tent Turtles, Pangshura tentoria, as well as a wide range of aquatic Birds. 

Much of the suitable Gharial nesting habitat on the Girwa River has been degraded by vegetational succession, following a channel shift in 2010, although conservationists are currently working on a project to build artificial sand banks, in order to create more suitable nesting sites. The population of Gharials on the Ghaghara River is considered to be threatened by flow regulation on the barrages, development of riverbank environments for agriculture, and fishing activities on the river.

Vashistha et al. recomend that a system of monitoring is developed for Gharails on the Ghaghara River, as well as the development of a co-operative program involving government agencies and local communities to conserve these Animals on both protected and unprotected rivers in the region.

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Alligator munensis: A new species of Alligator from the Quaternary of northern Thailand.

The  Alligatoridae (Alligators and Caimans), is now known almost exclusively from the Americas, with a single Asian example, the Chinese Alligator, Alligator sinensis, which molecular clock studies have suggested diverged from its closest living relative, the North American Alligator, Alligator mississippiensis, in the Eocene or Early Oligocene. The fossil record of Alligators in Asia has been poorly studied, which makes it difficult to assess the origin of the Chinese Alligator, and under what circumstances its ancestors migrated from America to Asia. 

To date, only a single extinct species of Alligator has been described from Asia, Alligator luicus from the Miocene of Shandong Province in northeast China. However, a range of specimens have been assigned to Alligator sinensis, from the Late Miocene onwards, from Thailand, Japan, and Taiwan, which may hide a greater diversity of extinct Alligators in the region.

In a paper published in the journal Scientific Reports on 13 July 2023, Gustavo Darlim of the Department of Geosciences at Eberhard Karls Universität Tübingen, Kantapon Suraprasit of the Department of Geology at Chulalongkorn University, Yaowalak Chaimanee of Laboratory PALEVOPRIM at the University of Poitiers, Pannipa Tian, Chotima Yamee, Mana Rugbumrung, and Adulwit Kaweera of the Thai Department of Mineral Resources, and Márton Rabi, also of the Department of Geosciences at Eberhard Karls Universität Tübingen, and of the Central Natural Science Collections at Martin-Luther University, redescribe the Thai example of 'Alligator sinensis', and make new assessments about its taxonomy, age, and ecology, as well as its implications for the distribution of modern Alligator sinensis populations. 

The specimen, DMR-BSL-2011–2, the  nearly complete cranium of an Alligator, was uncovered in 2005 by a group of villagers excavating a pond at Ban Si Liam in Nakhon Ratchasima Province, northeastern Thailand. It was found within a layer of yellowish medium- to fine-grained sands about 2 m thick, which lay immediately beneath a 30 cm thick, organic-rich topsoil layer. Beneath the yellowish sand was a layer of indurated iron oxide, and then a yellowish clay. As this was an agricultural project carried out by local people, rather than a palaeontological dig, no attempt at dating the material was made at the time. 

The fossil site of Ban Si Liam in Non Sung district (Nakhon Ratchasima), photo taken during the excavation. Darlim et al. (2023).

The topsoil layer is reported to have yielded a number of pottery fragments, while the sand layer also produced a fragment of Turtle shell, a Crocodylian vertebra, and fragments of a Wild Water Buffalo, Bubalus arnee, and a Sambar Deer, Rusa unicolor. It has previously been suggested that the yellowish sand and its faunal contents should be regarded as Late Miocene to Middle Pleistocene in age, by Darlim et al. disagree with this, noting that Miocene deposits in the Mun River Valley are typically found 10-20 m beneath the surface, and that the presence of Wild Water Buffalo and Sambar Deer suggests a date no older than the late Middle Pleistocene, with these Animals being known from the faunas of Tam Wiman Nakin (considered to be more than 169 000 years old, and Khok Sung, which has been separately dated as either 217 000 years old or 130 000 years old). Furthermore, since these species are still extant in the region, a Holocene date for the deposit cannot be excluded.

Locality of DMR-BSL-2011–2. (a) Schematic drawing of the map of Thailand. (b) Geological map of Nakhon Ratchasima province. Red star indicates the locality of DMR-BSL-2011–2. Orange polygon indicates Quaternary fossil site of Khok Sung; (c) stratigraphic profile of the fossil site of Ban Si Liam in Non Sung district (Nakhon Ratchasima) showing the level where DMR-BSL-2011–2 was found as indicated by the bone and alligator silhouette. Darlim et ai. (2023).

Examination of DMR-BSL-2011–2 led Darlim et al. to conclude that it represents a new, undescribed, species of Asian Alligator, which they describe as Alligator munensis, where 'munensis' means 'from Mun' in reference to the Mun River Valley, where the specimen was found. The skull of Alligator munensis is compressed anteroposteriorly, with external nares (nostrils) far back on the dorsal portion of the snout compared to other Alligators. The maxillary has no remaining teeth, but has only 12 alveoli (sockets), a significant reduction compared to other Alligator species. 

Skull of Alligator munensis, holotype (DMR-BSL-2011–2). Photo and schematic drawing in (a), (b) dorsal, and (c), (d) ventral views, respectively. bo basioccipital, ch choana, ect ectopterygoid, en external nares; f frontal, if incisive foramen, itf infratemporal fenestra, j jugal, l lacrimal, mx maxilla, n nasal, p parietal, pf prefrontal, pl palatine, pt pterygoid, pmx premaxilla, op occlusal pit, po postorbital, pop paroccipital process, q quadrate, qj quadratojugal, r ridge, rr rostral ridge, sof suborbital fenestra, sq squamosal, stf supratemporal fenestra, 4th, fourth maxillary alveolus; 12th, twelfth maxillary alveolus. Scale bar is 10 cm. Darlim et al. (2023).

Darlim et al. intend to publish a full taxonomic review of Alligator munensis elsewhere, but note that they believe it to be closely related to Alligator sinensis. Northern Thailand is a considerable range extension for Alligators, with Alligator sinensis being known only from the Yangtze and Xi river systems of China. These rivers come close to the Mekong and Chao Phraya systems of Thailand only in their upper reaches in the high Himalayas, an environment quite unsuitable for Alligators. However, the Himalayas are a relatively young mountain range, and it is possible that a Miocene ancestor of Alligator munensis and Alligator sinensis could have occupied the upper and lower reaches of both river systems, becoming separated into separate populations as the Himalayas rose, and eventually evolving into two different species.

Skull of Alligator munensis holotype (DMR-BSL-2011–2) and schematic drawing in right (a), (b) and left (c), (d) lateral views, respectively. bo basioccipital, eam external auditory meatus, ect ectopterygoid, en external nares, exo exoccipital, f frontal, itf infratemporal fenestra, j jugal, l lacrimal, ls laterosphenoid, mx maxilla, n nasal, pbs parabasisphenoid, pf prefrontal, pfp prefrontal pillar, pmx premaxilla, po postorbital, pop paroccipital process, pt pterygoid, q quadrate, qj quadratojugal; qjas quadratojugal articular surface, rr rostral ridge, sq squamosal; V foramen for the trigeminal nerve. Scale bar is 10 cm. Darlim et al. (2023).

The nares of Alligator munensis are far back, and located in a dorsal position on the snout, something not seen in any living Crocodilian. This state is seen in living Cetaceans, and extinct groups such as Ichthyosaurs, Plesiosaurs, Mesosaurs, and Metriorhynchid Crocodylomorphs, and in all cases appears to be an adaptation to a marine environment. However, this seems unlikely in Alligator munensis, not just because the single known specimen comes from a river sands deposit, not thought to have been laid down close to the sea, but also because all known species of Alligator lack lingual salt-excreting glands, which limits their ability to survive in marine waters.

Alligator munensis also has robust, deep skull, wide posterior process of the maxilla lateral to the suborbital fenestra, robust ectopterygoids, wide palatinal bridge between the suborbital fenestrae, and large and extended pterygoid flanges. This is a morphology consistent with a strong bite force and crushing dentition, something thought to have been the ancestral state in Alligatorines. This does not necessarily imply a particularly specialised diet in a Crocodilian, it is quite possible that such dentition would be found in an omnivorous species able to take tougher food, such as Molluscs or Turtles, but not dependent on such. The diet of Alligator sinensis has not been extensively studied, but Snails are thought to form an important part of its diet.

Virtual representation of Alligator munensis holotype (DMR-BSL-2011-2). (a) Digital reconstruction and (b) artistic reconstruction, both in lef lateral views. Scale bar is 10 cm.  Márton Szabó in Darlim et al. (2023).

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Remains of missing fisherman found inside two Crocodiles in northern Queensland.

The remains of a fisherman who went missing in the Rinyirru (Lakefield) National Park in northern Queensland, Australia, have been found inside two Crocodiles close to the area where he went missing. Kevin Darmody, 65, vanished while fishing with friends on the Kennedy River on 29 April this year, with witnesses reporting hearing a scream and a loud splash at about the time when he vanished. Following a search that lasted several days, local police located and killed two Saltwater Crocodiles, Crocodylus porosus, slightly upstream of the area where he went missing. To their surprise, Human remains believed to have come from Mr Darmody were found inside both Animals, something rare in cases of Crocodile attacks.

Kevin Darmody, 65, went missing while fishing in the Rinyirru (Lakefield) National Park on 29 April 2023, and believed to have been eaten by Crocodiles. Brisbane Times.

Crocodile attacks on Humans are relatively rare, but they are opportunistic ambush predators and will potentially attack anything going close to the water. Saltwater Crocodiles have a particularly poor reputation for such behaviour, being the largest species of Crocodile and notoriously aggressive. These Crocodiles are one of the few Crocodile species not considered vulnerable to extinction, being found from India to Australia  and inhabiting many areas that Humans shun, such as Mangrove forests and islands without fresh water.

A Saltwater Crocodile, Crocodylus porosus, in northern Queensland. Christopher Testa/ABC News.

Despite this fearsome reputation, attacks by Saltwater Crocodiles are still unusual, with only 13 fatalities recorded in Queensland since records began in 1985, and only one other attack involving more than one Crocodile. Despite this, calls for a cull of Crocodiles in parts of Queensland where they come into conflict with Humans are common, particularly after attacks, and this incident has not been an exception. Crocodiles are protected in Queensland, where hunting led to their population falling to around 5000 in 1974. Since that time the population has recovered at a rate of about 2% per year, with the current population estimated at between 20 000 and 30 000, most of which live around Cape York and the Gulf of Carpentaria.

Conservationists in Queensland oppose a cull of Crocodiles not just because this would be bad for the Crocodiles, but because they do not believe it would be good for people. They argue that the likelihood of Crocodile attacks is more closely related to Human behaviour than Crocodile population density, and that a cull might make people more complacent in Crocodile habitats, and therefore vulnerable to attacks. Instead they argue for education campaigns to raise public awareness of Crocodiles and how to behave around them.

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Crocodile captured after attacking 12-year-old girl in Northern Territory, Australia.

A 12-year-old girl has escaped with minor injuries after being attacked by a Saltwater Crocodile, Crocodylus porosus, while collecting water plants for a Fish tank in a creek to the south of Darwin on Thursday 16 March 2023. The girl was treated at the Palmerston Regional Hospital in Darwin, before being discharged, while the Crocodile was captured in a trap set by park rangers and will be relocated. A spokesperson for the Northern Territory Crocodile Management Team has stated that the girl was extremely lucky not to have received more serious injuries as the Crocodile was about 2.2 m in length, large enough to inflict significant injuries on an adult Human. Water levels are currently high in the Northern Territory, due to the annual rainy season, and Crocodiles are able to enter many waterways which are to shallow to offer them good cover at other times of year. Rangers have removed about 70 Crocodiles from such waterways so far this year, compared to a total of 273 removed in 2022.

Crocodile captured in a creek to the south of Darwin after attacking a 12-year-old girl on Thursday 16 March 2023. Department of Environment, Parks and Water Security.

Crocodile attacks on Humans are relatively rare, but they are opportunistic ambush predators and will potentially attack anything going close to the water. Saltwater Crocodiles have a particularly poor reputation for such behaviour, being the largest species of Crocodile and notoriously aggressive. These Crocodiles are one of the few Crocodile species not considered vulnerable to extinction, being found from India to Australia  and inhabiting many areas that Humans shun, such as Mangrove forests and islands without fresh water.

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