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Crocodilians are distributed widely through the tropics and subtropics, and several species pose a substantial threat to human life. This has important implications for human safety and crocodilian conservation. Understanding the drivers of crocodilian attacks on people could help minimize future attacks and inform conflict management. Crocodilian attacks follow a seasonal pattern in many regions, but there has been limited analysis of the relationship between attack occurrence and fine-scale contemporaneous environmental conditions. We use methods from environmental niche modelling to explore the relationships between attacks on people and abiotic predictors at a daily temporal resolution for the Nile crocodile Crocodylus niloticus in South Africa and Eswatini (formerly Swaziland), and the American alligator Alligator mississippiensis in Florida, USA. Our results indicate that ambient daily temperature is the most important abiotic temporal predictor of attack occurrence for both species, with attack likelihood increasing markedly when mean daily temperatures exceed 18 °C and peaking at 28 °C. It is likely that this relationship is explained partially by human propensity to spend time in and around water in warmer weather but also by the effect of temperature on crocodilian hunting behaviour and physiology, especially the ability to digest food. We discuss the potential of our findings to contribute to the management of crocodilians, with benefits for both human safety and conservation, and the application of environmental niche modelling for understanding human–wildlife conflicts involving both ectotherms and endotherms.

Conflicts with wildlife are a major challenge for conservation across Africa, and Nile crocodiles Crocodylus niloticus are allegedly responsible for more attacks on people than any other species; however, there is a lack of data regarding such attacks. We analysed reported attacks on people by Nile crocodiles in South Africa and eSwatini (Swaziland) during 1949–2016, identifying spatial and temporal patterns in attack incidence, as well as victim demographics. Through a literature review and archival searches we identified records of 214 attacks. Most attacks occurred in natural water bodies, with attacks in dams increasing since 2000. Most victims were attacked while swimming or bathing, others while fishing, doing domestic chores, and crossing waterways. There was a significant relationship between gender and activity when attacked. Children (< 16 years old) accounted for 51% of all attacks, with a higher fatality rate compared to adults. Most victims were male (65%), with teenage boys being the largest individual category. We make recommendations for conservation policy and management to mitigate attacks by Nile crocodiles.

The Greater Sunda region of South-east Asia supports a rich diversity of economically and ecologically important species. However, human pressures are reshaping contemporary biogeography across the region. Megafaunal distributional patterns have been particularly affected because of deforestation, poaching and human–wildlife conflict. Crocodilians are at the centre of these conflicts in Indonesia and yet remain poorly studied across much of the archipelago. We conducted population surveys of salt-water crocodiles Crocodylus porosus and false gharials Tomistoma schlegelii in Sumatra, and examined whether crocodile abundance and distribution are correlated with variations in human disturbance, fishing pressure, and habitat type. We then used these data to model remaining suitable habitat for T. schlegelii across South-east Asia. We found that abundance of T. schlegelii and C. porosus was correlated with distance from human settlements, and fish-trapping pressure. We recorded the presence of T. schlegelii in a river system in which it was previously unknown, thus expanding the known range of the species. We also found that the predicted remaining suitable habitat for T. schlegelii in Indonesia is largely limited to areas of low human activity. From these empirical and modelling approaches we propose several key conservation priorities: (1) eliminate the use of fish traps in remaining patches of T. schlegelii habitat, (2) prioritize crocodile population surveys in remaining suitable habitat, particularly in remote areas, (3) consider T. schlegelii to be potentially Endangered locally in Sumatra, and (4) expand existing reserves around the Lower Kampar River and Berbak National Park/Sembilang National Park areas of Sumatra.

The incidence of human–crocodile conflict is increasing, and fear of injury and loss of life is affecting public and political support for crocodile conservation. We studied conflicts between people and estuarine crocodiles Crocodylus porosus across socio-economic dimensions, using a spatio-temporal database. We collected data on 127 crocodile attacks that occurred during 2000–2013, through questionnaires including open- and close-ended questions, administered in 30 villages of five blocks of the Indian Sundarban. Most of the attacks (42%) occurred during winter (December–February), followed by the early monsoon (May–July; 27%). Almost 80% of victims were prawn seed collectors and were 11–50 years old, and 61.16% of victims died as a result of the attacks. Female victims accounted for a higher percentage of deaths (55.12%) than male victims (44.88%). Crocodile attacks were more common in the daytime than at night, with 76.35% of the killings occurring during 08.00–17.00. Most of the cases were recorded from Gosaba (34%), followed by Patharpratima (25.24%) and Namkhana (18.45%) blocks. The mean number of incidents per year was 9.07, with vulnerability and mortality rates of 0.07 and 0.04, respectively, per 10,000 persons. Existing management practices are insufficient to eliminate the risk of crocodile attacks and ensure the conservation of the Sundarban ecosystem. A comprehensive management plan for reducing dependency on forest resources is needed to minimize human–crocodile conflict.

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 crocodilesCrocodylus porosusis a growing industry in Australia's Northern Territory. Although Indigenous people sell crocodile eggs and hatchlings, the majority of harvesting and incubation is done by non-indigenous people from less remote areas. One Indigenous community has been heavily involved in this industry and now manages its own harvest and incubation programme. We present a case study of this programme, which has transitioned from outside agencies managing the harvest, to complete local ownership and management. Egg harvests and incubation success rates declined by 40% following the switch to local management. Income increased, as did production costs; in particular, royalty payments made to Indigenous landowners. The declines reflect the community's motives for engaging in the industry, which have been socially rather than commercially driven, and damage to nesting habitat by feral animals. The increase in royalties reflects the need to compete with non-indigenous harvesters from outside the township, who are strictly commercially driven. Harvesting, incubation and trade in crocodile eggs and hatchlings can form a viable and sustainable enterprise for remote Indigenous communities. However, efficiency needs to be improved to fulfil the need for a reliable and dependable supply chain, and regulatory institutions should give Indigenous harvesters sufficient freedom to pursue innovative and viable livelihood options.

As human populations grow and transform undeveloped terrestrial and aquatic habitats, human–wildlife conflict inevitably increases. This is particularly problematic for large predators and the humans who live alongside them. Relatively little research has been conducted on alleviating adverse human encounters with one of the most significant predator species in Africa, the Nile crocodile Crocodylus niloticus. This short communication raises questions about some of the general statements made to explain the incidence of attacks by crocodiles. Some of the limitations of the data on such attacks are considered, with recommendations on what kinds of data are required. Data collection and analysis, and how they can inform more effective mitigation efforts, are discussed.

Concern has been raised about the lack of population data for the Nile crocodile Crocodylus niloticus in the lower/middle Zambezi valley. This area is important for conservation as well as being a source of crocodile eggs and adults for the ranching industry. Two spotlight surveys, in 2006 and 2009, were used to estimate population size, structure and trends. A stage-structured matrix model was parameterized from existing literature and the expected predictions were compared to those observed. The survey data suggests a population increase since 2006. Crocodile density was greatest (3.1 km−1) in the areas of increased wildlife and habitat protection and lowest (1.4 km−1) in areas of increased human presence. The predicted population stage structure differed to that observed, suggestive of a population not at equilibrium. Data on offtakes of crocodile eggs and adults would be useful for examining why this is the case. Continued monitoring of the wild population is necessary, to evaluate the trend of an increasing crocodile population, and additional demographic data for modelling purposes would be desirable.

Populations of the common hippopotamus Hippopotamus amphibius in Mozambique were surveyed in 2010 during a national survey of the crocodile Crocodylus niloticus. Numbers of hippos seen during aerial counts along major rivers and lake shores were corrected to allow for undercounting of groups and these data were supplemented with the results of other recent surveys. There are now estimated to be c. 3,000 hippos in Mozambique and c. 50% of these live in Lake Cabora Bassa or the Zambezi River. The national total is much lower than the figure of 16,000–20,500 hippos estimated in 1986, used for the latest (v. 2012.1) IUCN Red List. The 1986 total included an estimated 10,000–12,000 in Marromeu Complex, an area that includes the southern Zambezi delta. We review the results of past surveys and find that the number of hippos in Marromeu Complex in 1986 was probably three times fewer than estimated. Although the number of hippos in this area declined markedly during the 1980s we believe that the 1986 overestimate of hippos in Marromeu Complex is an error that has been perpetuated for 25 years. Particular care should be taken when Red List assessments roll-over old and unsupported estimates of numbers. Even if an old estimate was accurate there comes a time when it should not simply be rolled-over. The 2007 IUCN Species Survival Commission's African Elephant Status Report provides a model for future assessments of the status of the common hippopotamus, categorizing the numbers of a species according to the type of survey, its reliability, and how long ago it was conducted.

In 1998 and 1999, relict populations of the Nile crocodile Crocodylus niloticus were rediscovered in south-eastern Mauritania, 70 years after the last reports of their existence and 6 years after the IUCN Species Survival Commission listed them as extirpated in that country. Crocodiles' were found in four different types of wetlands, herein described. Preliminary observations on their natural history and their interactions with humans are provided, and the main threats and the prerequisites for their protection are discussed.

The population and conservation status of crocodiles throughout West and Central Africa is poorly known and the IUCN Crocodile Specialist Group's highest priority recommendations are country status surveys and examination of potential threats. This study presents survey data and a review of the conservation status of the Nile crocodile Crocodylus niloticus, slender-snouted crocodile Mecistops cataphractus and African dwarf crocodile Osteolaemus tetraspis at 67 sites throughout Ghana and Cote d'Ivoire. No crocodiles were sighted in 31.5% of surveys but, where encountered, densities averaged 0.90 crocodiles sighted km-1. The most frequently encountered crocodile was C. niloticus (94% of sightings) with population structure highly biased to individuals < 1 year of age (41.4%). Only 14 M. cataphractus were observed. Local informants report that crocodiles were more common 10–20 years ago than at present. There is now little commercial harvest, which includes limited use in the bushmeat and traditional medicine markets, because of the crocodile's scarcity. Habitat encroachment and incidental bycatch in fishing devices appear to be the major threats. Actions needed to improve the conservation status of crocodile populations in both countries, and throughout the region, are discussed.

The estuarine crocodile Crocodylus porosus was formerly abundant in coastal regions of Myanmar, but is now known principally from the lower Ayeyarwady Delta. We conducted a survey during January 1999 to assess quantitatively the status of crocodile populations in protected areas of the lower delta. Spotlight counts were conducted along 275.4 km of waterways. Sixty-one crocodiles (50 juveniles, 4 subadults, 2 adults and 5 eyeshines) were observed in the Meinmahla Kyun Wildlife Sanctuary (MKWS), and the total population was estimated to be less than 100. The Kadônkani and Pyindaye Reserved Forests (RF) apparently no longer support viable populations. Although crocodiles remain critically endangered in the region, a comparison with survey data from 1980 suggests localized recovery is occurring in MKWS. Population declines are attributed to a combination of commercial skin hunting, habitat loss, drowning in fishing nets and over-collection of living animals to supply crocodile farms. A programme of law enforcement, habitat protection and head-starting juveniles is necessary to ensure the continued survival of estuarine crocodiles in the Ayeyarwady Delta.