The aim of this study was to assess welfare outcomes of electrical stunning as a means of restraint in farmed grower saltwater crocodiles (Crocodylus porosus). Physical handling of a stunned, unconscious crocodile is far safer for the operator than handling a fully conscious animal. Electroencephalogram (EEG) was recorded before and after the application of electrical stunning at 50 Hz or 400 Hz using an electrical stunner applied to the cranial plate (Position 1: P1–50 Hz; n = 31, P1–400 Hz; n = 29) or immediately behind the skull (Position 2: P2–50 Hz; n = 29; P2–400 Hz; n = 30). For all electrical stuns, percentage total EEG power in a 10-s epoch decreased in the alpha and beta frequency bands; and increased in the delta and lower frequencies bands. All electrical stuns resulted in increased strength of signal, based on the quadratic mean EEG power in all frequency bands of the EEG. Greatest change in power occurred in the delta frequency band, with P1–50 Hz. This was greater than with P2–50 Hz; while decibel change using 400 Hz at either position was intermediate and not significantly different from either. Application of either electrical stunner at position 1 resulted in seizure-like activity and activation in low frequencies, but at position 2 this was not consistent across all animals. The ability of the electrical stunning equipment to consistently induce recoverable unconsciousness could be ranked in decreasing order as: P1–50 Hz > P1–400 Hz = P2–50 Hz > P2–400 Hz. Based on behavioural observations, all animals in the study appeared to stunned however evaluation of duration of EEG changes indicates that use of the electrical stunning equipment at 50 Hz would allow some margin for inaccuracies in tong placement, while achieving a consistently reliable stun.

Negative interactions between people and crocodilians have increased worldwide, but in Mexico there have been few systematic reports and no rigorous evaluation of this problem. We compiled information on negative interactions between people and the spectacled caiman Caiman crocodilus and American crocodile Crocodylus acutus from the Worldwide Crocodilian Attack Database for 1993–2018, and we investigated interactions in greater depth, through interviews with people in La Encrucijada Biosphere Reserve. We examined the relationship between the occurrence of negative interactions between people and C. acutus and the species' nesting season and abundance, and presence records. In Mexico, the frequency of negative interactions increases when anthropogenic activities occur close to nesting sites (< 30 km) and during the nesting season (February–September). In La Encrucijada, following negative interactions with crocodiles, the local inhabitants killed 30 crocodiles measuring > 2.5 m long in 2011–2012. The frequency of negative human–crocodilian interactions was not correlated with the abundance of crocodilians but was correlated with the number of presence records of crocodiles. Strategies to minimize these interactions include warnings at nesting sites, increased monitoring of anthropogenic activities during the nesting season, and management of nests to prevent them being destroyed by people.

The conservation status of threatened taxa may be obfuscated by the detection of cryptic species complexes, in both vertebrate and invertebrate species. African dwarf crocodiles (Osteolaemus spp.) are hunted throughout their range but their conservation status is unknown. Few population assessments have been carried out and there has been a taxonomic revision of the number of species in the genus. The similar morphologies of Osteolaemus tetraspis and Osteolaemus osborni pose a challenge for conservation in Cameroon, where they are still managed as a single species. Nocturnal spotlight surveys were conducted in three regions during August–November 2010 and December 2011–February 2012 to provide population assessments of O. tetraspis and O. osborni and raise awareness of the two species in Cameroon. The mean encounter rates of O. tetraspis and O. osborni were 1.02 ± SD 1.34 (65 individuals in 39 surveys) and 0.61 ± SD 0.38 (three in four surveys) crocodiles per km, respectively. The O. tetraspis population comprised juveniles predominantly and had a male-biased sex ratio. The few O. osborni detected comprised both adults and juveniles. Both species are threatened in Cameroon, based on low encounter rates, young population structures and the threats of habitat loss and hunting pressure. This study provides distribution maps and serves as a baseline to quantify population trends and inform conservation strategies.

Human–wildlife conflicts are common across Africa. In Mozambique, official records show that wildlife killed 265 people during 27 months (July 2006 to September 2008). Crocodile Crocodylus niloticus, lion Panthera leo, elephant Loxodonta africana and hippopotamus Hippopotamus amphibius caused most deaths but crocodiles were responsible for 66%. Crocodile attacks occurred across Mozambique but 53% of deaths occurred in districts bordering Lake Cabora Bassa and the Zambezi River. Hippopotamus attacks were also concentrated here. Lion attacks occurred mainly in northern Mozambique and, while people were attacked by elephants across the country, 67% of deaths occurred in northern Mozambique. Attacks by lions, elephants or hippopotamuses were relatively rare but additional data will probably show that attacks by these species are more widespread than the preliminary records suggest. Buffalo Syncerus caffer, hyaena Crocuta crocuta and leopard Panthera pardus were minor conflict species. Good land-use planning, a long-term solution to many conflicts, is particularly relevant in Mozambique, where the crocodile and hippopotamus populations of protected areas are often in rivers that border these areas, and cause conflicts outside them, and where people commonly live within protected areas. Poverty may prompt fishermen to risk crocodile attack by entering rivers or lakes. The high incidence of conflicts near Limpopo and South Africa’s Kruger National Parks (both within the Great Limpopo Transfrontier Conservation Area) highlights the problems created for people by facilitating the unrestricted movement of wildlife between protected areas across their land.

A representative sample of waterways in Liberia was surveyed for crocodiles, and all three species of African crocodiles were observed. Contrary to previous reports, only Nile crocodiles inhabit the Monrovia mangrove swamps and brackish-water mouths of rivers; there are no slendersnouted or dwarf crocodiles in these habitats. There is partitioning of habitats among the three species in Liberia: Nile crocodiles in mangrove swamps and river mouths (brackish water); slendersnouted crocodiles in rivers through rain forest (freshwater); and dwarf crocodiles in small streams through rain forest (freshwater), some entering the adjacent river. Dwarf crocodiles utilize burrows in the stream banks.

Nowhere are crocodiles abundant, and there is an apparent absence of adults. Although 40% of Liberia is forested, deforestation is occurring rapidly by foreign timber companies and slash-and-burn agriculture practised by the largely rural population. Hunting with firearms, although illegal, is widespread, both for subsistence and commercially, without concern for depletion. Mangrove ecosystems near human population centres are being destroyed. The combination of the above factors has apparently depleted the crocodile populations in Liberia.

A total of 14 spotlight surveys were carried out from January 1992 to February 1993 along 37 km of the Klias River in north-western Sabah, Malaysia. Surveys were at low tide between 1900 and 0600 h from a survey boat at 15 km h−1 by two observers. A total of 221 sightings were made, which varied between 2 and 29 per survey (mean 15.8). A total of 55 juvenile crocodiles were captured, with 16 recaptures. Calculated density was 0.9–1.8 individuals km−1, while the estimated crocodile population was 46.1 ± 10.2 (SD) for the survey area. Percentage sightings according to total length were: 42% ≤0.5 m; 40% >0.5-≤1.0 m; 5% > 1.0-≤3.0; and 13% eyes only. Recapture of 16 tagged juveniles suggested that hatchlings ≤0.5 m total length remained within >0.5 km of their release point for at least one month, and juveniles 0.5-≤1.0 m more than one year. Hatchlings had growth rates between 0.01 and 0.08 cm d−1 and 0.3 and 1.5 g d−1, while larger juveniles grew at least 0.11 cm d−1 and 2.7–2.9 g d−1. Stomachs of hatchlings and juveniles contained crabs (Ocypodidae), prawns (Atyidae), insects and small fish (Hemiramphidae). Relatively large numbers of juvenile Crocodylus porosus (82.4%) in the Klias River suggests that the area, though under hunting pressure, is desirable as a site for the conservation of C. porosus in the Sabah.

Progarnia archosauriae nov. gen., nov. sp. (Haemosporina: Garniidae) is described in the blood of the South American caiman, Caiman crocodilus crocodilus (Archosauria: Crocodilia). The parasite undergoes merogony and gametogony principally in leucocytes and thrombocytes, but also invades erythrocytes in which it produces no ‘malarial’ pigment. It thus shares features of Fallisia and Garnia which are, respectively, intra-leucocytic and intra-erythrocytic haemosporines of the family Garniidae in present-day lizards. This, and the antiquity of the order Crocodilia, suggests that it was from such a parasite that the existing reptilian and avian haemosporines evolved. An overall evolutionary pattern is suggested.

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 Côte 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 cross-sectional geometric properties of the crocodylian humerus were examined in order to assess the effects of differential locomotor behaviour and habitat use on osteological properties. Several biomechanical properties of the humerus were calculated, including resistance to compression and tension, bending and torsion resistance. The biomechanical properties of the crocodylian humerus reflect little variation attributable to locomotor behaviour or natural habitat use (terrestrial vs aquatic habitat). However, the biomechanical properties of captive individuals differed from those of wild conspecifics. The results of this research suggest that crocodylian humeri maintain sufficient resistance to all loading conditions throughout life with little remodelling, though both resorption and remodelling of bone are known to occur. Consequently, crocodylian humeri do not respond to stresses incurred during life as predicted by Wolff's Law.