Friday, 4 October 2019

Investigating Crocodile attacks in South Africa and eSwatini.

Conflicts between Humans and animals present a major challenge in conservation work, particularly where animals are prone to attacking Humans or livestock. The most common perpetrators of such attacks in Africa are Crocodiles, with two species, the Nile Crocodile, Crocodylus niloticus, and the West African Crocodile, Crocodylus suchus, together coming the overwhelming majority of wildlife attacks on the continent. Nile Crocodiles are particularly dangerous, with the largest males reaching around five metres in length, and a diet that includes animals such as Wildebeest, Connochaetes spp., and Buffalo, Syncerus caffer, species which it requires considerable strength to subdue. Crocodiles are extremely versatile in their environmental tolerances; they are semi-aquatic, but dwell in a range of habitats from large, fast flowing rivers to small ponds, and have quickly colonised Human-made environments such as canals, dam lakes and even irrigation ditches, creating extra opportunities for conflict with Humans. Despite the obvious hazards presented by Crocodiles, there have been very few organised studies of their behaviour and conflict with Humans.

In a paper published in the journal Orynx on 11 July 2019, Simon Pooley of the Department of Geography at Birkbeck University of London, the School of Life Sciences at the University of KwaZulu-Natal, and WildCRU at the University of Oxford, Hannes Botha of Scientific Services at the Mpumalanga Tourism and Parks Agency, and the Department of Biodiversity at the University of Limpopo, Xander Combrink of the Department of Conservation Science at the Tshwane University of Technology, and George Powell of the Department of Life Sciences at Imperial College London, present the results of a study of reported attacks on people by Nile crocodiles in South Africa and eSwatini (Swaziland) during the period 1949-2016.

Nile Crocodiles, Crocodylus niloticus. AFP/Getty Images.

The study area included north-eastern South Africa, including the warmer, low-lying (lowveld) region of the interior confined mainly to Limpopo and Mpumalanga Provinces, and northern KwaZulu-Natal Province, and the lower-lying warmer areas of eSwatini. Nile crocodile distribution in the region is limited to the warmer, summer rainfall regions of these countries, with the hot and wet season (with minimum temperatures above 15°C) during October–March (November–March in the interior of South Africa). Most of the rivers flow eastwards, from the central plateau and eastern escarpment to the Indian Ocean.

North-eastern South Africa and eSwatini (Swaziland), with the provinces of South Africa, key protected areas, rivers in which Crocodile attacks have occurred, and the locations of fatal and non-fatal attacks. Dams shown on the map are: (1) Makuleke Dam, (2) Middle Letaba Dam, (3) Flag Boshielo Dam, (4) Rust de Winter Dam, (5) Loskop Dam, (6) Driekoppies Dam, (7) Pongolapoort Dam, and (8) Goedertrouw Dam. Pooley et al. (2019).

The political landscape, and therefore land use, in South Africa changed radically over the period of the study. From 1949–1992 South Africa’s black African majority was persecuted under the system of Apartheid, with resettlement in remote rural homelands with poor land and few jobs, and men working in cities as migrant labourers. This system kept two-thirds of the population rural (some of them more likely to encounter crocodiles) until the early 1980s, when Apartheid began to fail. Apartheid influx laws were defied, and urbanisation accelerated, especially after an African National Congress-led government came to power in 1994. Employment in the agricultural sector is now low (5.6%) and declining, with unemployment much higher in rural areas. Census data from the Apartheid era are considered to be highly questionable, and the borders of magisterial districts varied
across the study period, and estimates of human population density exist only at a coarse scale.

eSwatini is a small, stable absolute monarchy with a largely rural population. The population increased sixfold during the study period. eSwatini is categorised as a lower middle income country, and the majority of Swazis are poor, with an estimated 70% of the population employed in subsistence farming. Many Swazis depend on rivers for water, for drinking, cooking and washing.

There are naturally occurring wild Nile crocodiles as far south as the Zinkwazi River in South Africa but the major viable populations are restricted to three disjunct protected areas: the eight large seasonal and perennial rivers traversing Kruger National Park in Limpopo and Mpumalanga provinces; and in KwaZulu-Natal Province, in Ndumo Game Reserve and the Lake St Lucia estuarine system.

A Nile Crocodile in the Kruger National Park. Trover.

Crocodile abundance in Kruger National Park peaked in the early 1990s and then declined during 1993-2000, but has since increased to an estimated 4300 individuals more than a metre in length. This is despite die-offs since 2008, caused by the nutritional disease Pansteatitis (Yellow Fat Disease). In Limpopo and Mpumalanga provinces, outside the Park just over 600 individual Ceocodiles were counted in the 1980s, most under three metres in length, with breeding populations in the Olifants, Limpopo, Luvuvhu, Komati and Blyde rivers. By the end of the study period only the 12.8 km² Flag Boshielo Dam on the Olifants River retained a viable Crocodile population outside Kruger National Park in Mpumalanga Province, and this population declined by 27% following the raising of the dam wall by5 m in 2006.

In northern KwaZulu-Natal Province, populations declined after World War II as a result of hunting and snaring, as well as habitat destruction and water shortages caused by the expanding agriculture and forestry sectors. A Crocodile restocking program was started in 1966 by naturalist and conservationist Tony Pooley, and legal protection for Crocodiles introduced in1969, resulting in a significant population recovery by the 1990s. However, the Ndumo Game Reserve population decreased by 38% during 1993-2000, possibly because of an increase in illegal killings and disturbance facilitated by the removal of the eastern boundary fence in May 2008, and in 2009 the population stood at 536 Crocodiles.

Lake St Lucia estuarine system in northern KwaZulu-Natal was restocked with juvenile Crocodiles during the period 1967-1976. The first aerial survey of Crocodiles in the lake in 1976 found a population of 356 animals more than a metre in length, and by 1993 this had risen to 975. The population remained stable until 2008 but has since declined, possibly as a result of prolonged drought.


A Nile Crocodile on the shore of Lake St Lucia. iSimangaliso Wetland Park.

With the exception of the 132 km² Pongolapoort Dam in KwaZulu-Natal declines have been reported for all major crocodile populations in South Africa. As a result, Nile crocodiles are categorised as Vulnerable in the country.

In eSwatini, extensive habitat has been converted for agriculture, and illegal hunting remained rife into the 1980s. In 1992 King Mswati III ordered a new draft of the Game Act, which introduced the
first legal protection for Crocodiles outside protected areas. No Crocodile population data are available for eSwatini, but the species is considered to be Vulnerable there.

Ezemvelo KZN Wildlife is the responsible authority in KwaZulu-Natal, South Africa. They remove rather than kill Crocodiles whenever possible, and do not erect or maintain protective structures, or pay compensation for attacks outside protected areas. The Mpumalanga Tourism and Parks Agency and Limpopo Province’s Department of Economic Development, Environment and Tourism deal with attacks in the interior. Crocodiles are protected under provincial conservation legislation.

In Mpumalanga problem crocodiles are trapped and released in either the Loskop Dam or Flag Boshielo Dam, or sold to commercial farms. The Limpopo authorities have issued tenders licensing trophy hunters to control damage-causing Crocodiles but few have been destroyed in this way. Fences have been built at some dams.

Ezemvelo KZN Wildlife Conservation Manager Mpume Ngcobo, of the St Lucia Crocodile Education Centre, releasing hatchlings into the protected kuNkazana Stream within the Eastern Shores section of the iSimangaliso Wetland Park. iSimangaliso Wetland Park.

In eSwatini, Big Game Parks is mandated by the office of the King to manage wildlife in the royal parks and outside protected areas. Their policy is to capture and remove confirmed problem crocodiles. No protective structures are built, and compensation is not paid.

Information on attacks by Nile crocodiles was obtained from the personal archives of conservationists Tony Pooley and Ian Player, the St Lucia Crocodile Centre, and the Times of Swaziland archive in Mbabane, eSwatini. Pooley et al. newspaper reports (print and online), journals and popular magazines, using the search term ‘crocodile’ paired with ‘attack’, ‘bite’ or ‘victim’, in English and Afrikaans.

Only details of attacks by wild crocodiles that resulted in injury or death were included. Alleged attacks that were not witnessed or that lacked forensic proof were excluded. Fatal attacks include attacks from which victims died later as a result of injuries sustained. Demographic categories for age
were child (under 16 years) and adult (16 years or older); sometimes exact age data were missing but victims were described as children or adults, and five year age categories were used for cases for which exact age data were available.

Crocodile attacks prior to 1949 were excluded because of a paucity of reliable data. It is likely that during the study period some attacks involving minor injuries went unreported. In remote regions, particularly areas to which people were relocated by Apartheid authorities, some serious attacks may have gone unreported.

A Nile Crocodile in eSwatini. Günther Eichhorn/Mlilwane Wildlife Sanctuary.

The literature searches returned 132 print newspaper stories and six magazine features for South Africa, and fifteen print newspaper stories of attacks in eSwatini. Sixteen online stories were retrieved through Google searches and searches of digital archives of five South African newspapers (in English and Afrikaans), and nine stories from the digital archives of two Swazi newspapers. Tony Pooley’s archive included personal records of 73 attacks in the study region, and Ian Player’s archive included 15 newspaper reports of attacks.

Overall the dataset comprises 214 crocodile attacks for the period 1949-2016: 185 attacks in South Africa and 29 in eSwatini. In South Africa, attacks have been recorded in 13 district municipalities but only five districts have more than five attacks recorded.  The majority of crocodile attacks occurred in natural water bodies with 50% of attacks in rivers or streams, 15% in lakes or pans, 3% in the St Lucia estuary, and 1% in wetlands, while 8% of attacks occurred in in dam lakes of various sizes, and 2% in canals or drains. The location of one attack was not given in the reports.

Crocodile attacks seemed to be closely related to season, with attacks far more common in the warm wet summer than in the cool dry winter. Three possible explanations for the seasonality of Crocodile attacks have been previously proposed: (1) increased Crocodile dispersal and encounter rates resulting from high rainfall and water levels, (2) Crocodiles are ectothermic and thus more active when it is warmer, and (3) increased aggression during the breeding season, Pooley et al. found that Crocodile attack incidence tracks high mean water levels (where data exist) and high monthly mean rainfall (particularly in the interior of South Africa), but that there is no significant relationship between individual attacks in the study region and high rainfall and water-level conditions recorded for dates of attacks only. They also note that previous studies have suggested that Crocodile attacks are more common in the dry season in neighbouring Mozambique.

A Crocodile in the Kruger National Park. flowcom/Flikr/Wikimedia Commons.

Monthly mean daily temperature is the strongest environmental predictor, with most attacks occurring at temperatures of at least 16°C. This effect of temperature could be explained by Crocodiles’ decreased physiological maintenance costs under cooler conditions and, conversely, increased activity levels and food requirements under warmer conditions.

The seasonality of crocodile attacks cannot be explained based on biophysical variables and Crocodile behaviour alone because of the overlap between Human and Crocodile activity (e.g. the seasonality of aquatic activity of both Crocodiles and people). Nearly half of attacks in the study region occurred on weekends and holidays, suggesting Human activity patterns are influential. Although the climate varies slightly between the interior and the coastal regions where crocodiles occur, the peak attack season is the same, December to March.

More data on local behaviour patterns of Crocodiles and people in hotspots for Crocodile attacks would contribute to more effective mitigation measures. For instance, it is known that Crocodiles congregate in lakes in Ndumo Game Reserve and on the eastern shores of Lake St Lucia in winter. Larger individuals disperse outside the protected areas or around the lake system in the summer. Thus in recreational areas around the Lake St Lucia system, notably the estuary, there are seasonal overlaps between the distributions of larger Crocodiles and people.

Nesting Crocodiles on the cliffs at Pongolapoort Dam, Northern KwaZulu-Natal. Champion (2010).

One hundred and ninety records include the activity the victim was engaged in when the attack occurred. Of these, most victims (29%) were attacked while swimming or bathing, followed by fishing (22%), doing domestic chores at the water’s edge (18%), crossing the water (16%), or other (13%). 65% of the victims of Crocodile attacks were male, and 45% female. Of the 139 reports including exact age information, 68% attacks (49%) were on adults (aged 16 years or older), and 71 attacks (51%) were on children (under 16 years). A greater proportion of the attacks on children were fatal (54%), compared with adults (35%).

The finding that it is mostly males that have been attacked in this region contradicts the assumption that in Africa women and girls are disproportionately at risk because of their domestic tasks at the water’s edge. The numerous attacks on females, most performing domestic chores, along the Pongola floodplain system in the 1960s and 1970s are atypical. Census data reveal a higher proportion of women than men resident in this region in this period, with men away working as migrant labourers. Pooley et al.s data show that domestic chores have been a less important factor in the wider region since around 2000, reflecting both the Crocodile’s contracting range and improved water provision in some rural areas.

A key finding is that 51% of victims were aged 0-15 years. That 62% of victims were aged 0-20 and the largest adult category was 21-30 (19%) may simply reflect the demography of the country (median age 26). Nevertheless, the high proportion of children, especially aged 11-15 years, 72.5% of whom were boys, suggests this should be a focus for concern and education.

The overall fatality rate from attacks was 49%, however, 57% of attacks on children (0-15 years) were fatal and 54% of victims aged 0-20 years were killed, in comparison with 40% of attacks on those aged at least 21 years. Fatality rates were influenced by whether the victim was accompanied or alone, and the size (length) of crocodile involved, as well as the size of the victim. Smaller victims (children) are more vulnerable to fatal attacks. Pooley et al. found that, of those adults who escaped death, 43% (22) escaped without help and 43% (22) were rescued, whereas only 35% (11) of children escaped unaided and 65% (20) were rescued.

Only 15 crocodiles involved in attacks were measured accurately, and therefore size data could not be used as an accurate variable. Furthermore, most Crocodile counts have been made from fixed-wing aircraft, so there are no general data on the size of Crocodiles to facilitate comparison of the number of fatal attacks with the proportion of large Crocodiles in wild populations. Comparing the length of crocodiles with fatality/non-fatality outcomes is complicated by age and size of victim, and whether there were rescuers present. Better data would be required to assess the relationship between size and deliberate attacks on people by Crocodiles in this region, although data from Alligators and Saltwater Crocodiles suggest that individuals measuring more than 1.8 m can inflict serious injuries, and individuals measuring at least 2.4 m carry out fatal attacks.

Overall, most victims were swimming, bathing or fishing, but desegregating data on activity of victim when attacked by age and gender reveals distinct profiles. Pooley et al.'s data show that until the 1980s most victims were performing domestic chores or crossing water when attacked, but since then these activities have been superseded by swimming and fishing.

Pooley et al. make several recommendations on how the risks associated with living with Crocodiles in South Africa and eSwatini could be mitigated in the future. For high risk areas there are a number of mostly low-cost actions that can be taken. Local authorities could facilitate safe water crossings, and safe access to water for swimming (particularly near rural schools) or domestic needs, including alternatives such as water tanks, piped water and protective enclosures. Provincial conservation authorities and district municipalities could create, equip and train teams to capture and remove problem Crocodiles. Where such teams already exist, it would be helpful to make them known to the public. If departmental resources are limited, a system of licensing private individuals (as in the USA) could be trialled. Some commercial Crocodile farmers already provide this service on an ad hoc basis. Removing Crocodiles requires the creation of clear protocols for disposing of captured Crocodiles.

Educating children should be a priority, particularly in identified high-risk areas. Outreach activities could be supported with existing materials that provide information on crocodile biology and behaviour, their ecological and conservation importance, as well as advice on avoiding and responding to attacks.

Provincial conservation authorities should appoint knowledgeable spokespersons to brief the public in the event of a Crocodile attack (or alleged attack). The accuracy of reporting would be improved by keeping detailed records of attacks, and building better communication between police, coroners and conservation authorities to ensure accurate information on causes of death are reported. In South Africa,where Crocodiles are farmed but not ranched (i.e. captive bred but not sourced from the wild) and there is no link between farming and the country’s wild populations of Crocodiles, and in a region where taboos against the eating of Crocodiles have recently been overturned, tolerance for wild Crocodiles should not be taken for granted.

See also...

https://sciencythoughts.blogspot.com/2019/09/diplocynodon-hantoniensis-alligatoroid.htmlhttps://sciencythoughts.blogspot.com/2019/09/malaysian-woman-killed-by-crocodile.html
https://sciencythoughts.blogspot.com/2019/06/isisfordia-molnari-new-species-of.htmlhttps://sciencythoughts.blogspot.com/2019/06/crocodiles-killed-in-solomon-islands.html
https://sciencythoughts.blogspot.com/2019/05/crocodile-kills-boy-in-maharashtra.htmlhttps://sciencythoughts.blogspot.com/2019/04/cricosaurus-bambergensis-new-species-of.html
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