Wildlife vs. infrastructure: How could we reduce conflicts?
by Line Faber Johannesen
One of the Largest Anthropogenic Causes of Wildlife Death
Mikumi National Park, Tanzania
A study from 1996 evaluated the effects of the A7 highway on large mammals of the Mikumi National Park in Tanzania. Park personnel recorded 456 highway mortalities of large mammals in the 16-year period between 1973 and 1988. (Newmark et al. 1996).
Not only are wildlife vehicle collisions [WVCs] a major concern for wildlife conservation, they also pose a serious concern for traffic and human safety and have the potential to cause severe economic losses. Mitigation strategies are often implemented to minimise or eliminate potential conflicts between infrastructure and wildlife but depending on the mitigation method, various rates of success have been reported.
WVCs causing animal mortality are one of the largest, if not the largest anthropogenic cause of wildlife deaths, according to John Griffin, Director of Humane Wildlife Services at HSUS, (Kelleher 2015).
A study by Centero Brasilero de Estudos em Ecologia de Estradas reported that an estimated 1.3 million animals die in Brazil every day from being struck by cars or trucks (Guimarães 2015). For Brazil alone 475 million animals are killed every year because of WVCs.
According to Conservation India, 75 elephants (Elephas maximus) were killed in train collisions in just a 7-year period.
Infrastructure effects on wildlife include more than just the direct mortality from collisions. They also generate disturbances relating to: traffic noise, habitat fragmentation, and altered spatial landscape patterns (Forman and Alexander 1998).
How can WVCS be mitigated?
Mitigation strategies are an integral part of Environmental Impact Assessments (EIAs) of infrastructure projects worldwide and of increasingly recognized legislative importance. The purpose of a mitigation strategy is to compensate for or eliminate the potential negative impacts of a certain action or construction. The implementation of wildlife tunnels, fauna passages and green bridges are just a few examples of such mitigations strategies often utilized in relation to infrastructure projects.
One such infrastructure project is the rehabilitation of the road between Senanga and Sesheke, Western Province in Zambia. This road runs through the Sioma Ngwezi National Park where a number of threatened species listed by the IUCN occur. Mammals such as Impala (Aepyceros melampus), Giraffe (Giraffa camelopardalis), Sable (Hippotragus niger), Roan (Hippotragus equinus) and Greater Kudu (Tragelaphus strepsiceros) migrate from Sioma Ngwezi and West Zambezi to the Zambezi River in the dry season and are therefore at risk of being killed in WVCs (COWI 2006).
The mitigation strategy implemented for the Senanga-Sesheke road rehabilitation project is the creation of permanent water holes in the central and eastern part of Sioma Ngwezi National Park to eliminate the need for wildlife to cross the road.
In Kenya, two populations of elephants (Loxodonta Africana) living in the Mount Kenya (region) had for many years been separated by the busy Nanyuki-Meru road. Approximately 2000 elephants lived in the Mount Kenya population while 7500 elephants lived in the Samburu-Laikipia population. Population fragmentation disabling migration between populations can be detrimental to the genetic health of a species.
A “trunk road” as a mitigation method was implemented to connect the two wilderness areas in Kenya and to reunite the two elephant populations. The “trunk road” was built as an underpass, guiding the elephants under the road. In 2011 the first elephant, known as “Tony,” was spotted by the Lewa Wildlife Conservancy, using the tunnel, thus crossing this major road without the risk of human or vehicular conflict. This $1 million underpass was underway in 10 years and didn’t secure
funding by donors till Sir Richard Branson donated $250,000 and the underpass is the second one created on the African continent (the first being in the South African KwaZulu Natal province). These elephant underpasses would also provide safe road passage for other wildlife in the area.
Additional to the two elephant underpasses exist on the African continent, both China and India have also implemented elephant underpasses, and India also has elephant overpasses.
In 2009, Indian authorities approved plans to build the worlds first “flyover” routes for elephants to save them from railway collisions at the Rajaji National Park in Uttarakhand state near the Himalayan foothills. The two proposed flyover routes would each be around 1.2 km long, 100 meters wide and covered in foliage to encourage the animals to use them. Construction halted in 2016 due to issues with the responsible construction company.
Other mitigation strategies in Rajaji National Park have been to provide the railway staff and guards with Awareness Training, clearing the mounds along the tracks to improve visibility, and the implementation of new water holes to minimize the need for elephants and other wildlife to cross the tracks. Finally, passengers are encouraged to not throw food out the train as to minimize the attraction of wildlife to the tracks. According to Conservation India, these strategies have reduced the number of incidents where elephants where injured on the railway.
Even with this focus on mitigation strategies to eliminate and minimize the adverse impacts roads have on populations of wildlife, roads through national parks are unpopular with conservationists and have caused public conflict leading to the abandonment of projects (Caro 2015; Dobson et al. 2010).
Back in Mikumi National Park, the records showed that the majority of large herbivore and carnivore mortalities occurred during the dry season of August, September and October (Newmark et al. 1996). In the same study, the results of transect surveys indicated that in grassland where the vegetation reached less than 1m in height, approximately half of the large diurnal mammals otherwise found in the Mkata flood plain of the Mikumi National Park, occurred less than expected in relation to distribution patterns within 200-600 meters of the A7 highway. This indicate that elephant, black-backed jackal (Canis mesomelas), eland (Taurotragus oryx), wildebeest (Connochaetes taurinus), bohor reedbuck (Redunca redunca) and zebra (Equus quagga) actively avoid the A7 highway during the dry season. In open woodland there was no significant difference in the observed distribution of zebra, impala and warthog in relation to the A7 highway. However, wildebeest were encountered less than expected 0-600 meters from the highway in in open woodland (Newmark et al. 1996). Newark et al. (1996) also noted an inverse relationship between highway mortalities and precipitation. The distribution of roadkill was found to be heterogenous as they were more likely to occur at the roadside surrounded by a thick vegetative cover (Kioko, Kiffner, Jenkins, et al. 2015).
On the A7 highway of the Mikumi National Park another mitigation strategy to minimize the potential for WVCs was the implementation of road bumps and imposed speed limitations as well as signs indicating wildlife crossings. However, there were no records of any wildlife mortality prior to the road bumps nor the speed limitations. It is however stated in Newark et al (1996) that while the speed limits exist, they are rarely enforced and the average vehicle speed in 1991 was about 80-110 km pr. hour.
The implications of WVCs in relation to conservation was investigated in Kioko, Kiffner, Phillips, et al. 2015 in Northern Tanzania, where authors found a significant discrepancy between driver awareness of the species most frequently impacted by WVCs and the species that actually had the highest rate of mortality due to WVCs. The perception of the driver as to which different species are most in jeopardy (certain birds in this study) is very relevant as to how the drive reacts in a situation where the specific species is spotted near the road.
456 large mammals were killed on the A7 highway in the 16-year period of 1973-1988 (Newmark et al. 1996), however no numbers exist on the number of birds or reptiles killed on the A7 highway in the same time period.
Increased policing and enforcement of speed limits could help minimize the potential for vehicular collisions with wildlife. Warning signs of crossing wildlife are readily available during the 50 km stretch of the A7 highway going through the Mikumi National Park (authors personal observation, 2018) however as reported in Kioko, Kiffner, Phillips, et al. 2015 from a study from Northern Tanzania, signs alone had a limited success rate because they were ignored by drivers as they become used to seeing them. A recommendation therefore is that road signs warning of wildlife crossing are flexible and altered during peak migration season, and used in combination with other mitigation strategies (Kioko, Kiffner, Phillips, et al. 2015).
Roads do not only pose a risk for wildlife directly through collisions with cars and trucks, they also present a barrier which can cause habitat fragmentation, eliminating the flow of individuals and thus genes between populations. Furthermore, the roads can provide easier access for poachers to the valuable and endangered species e.g. elephants and cause overall habitat disturbance that a road cause (Dobson et al. 2010).
The results of the 1996 Newark et al. study found significantly less observations of certain wildlife, such as wildebeest within a certain distance to the road, thereby highlighting the disturbance and habitat fragmentation the A7 highway causes by bisecting the Mikumi National Park. If the mitigation strategy proposed for the Senanga-Sesheke road project in Zambia were to be implemented in the Mikumi National Park, that is the creation of permanent water holes to eliminate the need for migration across the road, the road would still cause habitat fragmentation and disturbance. The creation of water holes also poses the potentially easier access for poachers to endangered species that would be gathered around the artificial water holes, thus there would be a need for policing. The creation of the water holes themselves would also be landscape and habitat alteration which could cause displacement of certain species impacted by the action. Vegetation clearing along the roadside would potentially minimize the risk of WVCs but would expand the width of the zone along the road where wildlife would be observed less, and habitat fragmentation and disturbance would still occur. The implementation of either tunnels, green bridges or passages could theoretically be done, however it would be a great financial commitment.
Mikumi National Park is the fourth largest national park in Tanzania with its 3230 sq km located between the Uluguru Mountains to the northeast, the Lumango Mountains to the southeast and the Rubeho Mountains to the northwest. For Mikumi National Park the most recent data available is from 1996, where, as previously stated, 456 large mammals were killed on the A7 highway in the 16-year period of 1973-1988 (Newmark et al. 1996). In order to fully grasp the extend of the issue of this busy road bisecting a national park, it is necessary to collect updated data, and for issue to be continuously monitored. On par with global traffic trends, this author deems it a fair assumption that traffic has increased since 1988, which begs the rationale that the potential for WVCs in Mikumi National Park has increased as well.
Training People to see Wildlife
While implemented mitigation strategies to eliminate the potential for wildlife to enter the road should be first priority, the alteration of driver mentality should definitely also be a consideration when concerned with conservation. It is important to create awareness and education on both the danger of wildlife collisions for personal safety, but more importantly the ways in which the driver can do to minimize the risk of collision. The Awareness Training of the railway staff and guards in India proved to be a useful mitigation strategy. Strict enforcement of speed limits and adherence to signs is crucial, as it is optimizing the location and timing of warning signs.
Whenever Roads are Necessary Through National Parks
Roads are a major cause of mortality for wildlife and it is necessary to consider when both implementing infrastructure through areas of high density of wildlife, or areas of high wildlife importance such as national parks. If it is at all possible to avoid major roads, or tarmacked roads through national parks, that should be the aim. Whenever a road through a national park is unavoidable it is necessary to investigate the potential for mitigation strategies to minimize the risk of WVCs, and it is necessary to enforce restrictions on driving speeds and to create awareness of the wildlife implications and conservation impacts that the road cause for drives and local authorities a like.
References
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