Roadkill

The roadkill is a term of Anglo-Saxon origin which describes the phenomenon of animal Mortalité by the collision with the vehicles.

The road collisions implying the fauna are in increase in the majority of the areas of the world, in particular in the and , developing countries North America Europe. The main reasons at the origin of this phenomenon are the increase in the grid systems, the increase mean velocity of the vehicles and their number. The demand and the supply growing in fast and effective means of transport contribute to a increasing fragmentation of the territories and natural habitats, as well as the increase in the number of vehicles and traversed mileage. The roadkill is intrinsically related to the Fragmentation écopaysagère and it is one of the major causes of disappearances of certain threatened species. In the poor countries where the bovines, sheep and équidés, like dogs and cats move along the roads, of many pets are also wounded or killed by vehicles. The accidents of vehicles with fauna have heavy consequences, as well in the field of the Biodiversité as of the economy. Moreover, these collisions pose serious problems of Road safety, they can arrive at any driver, even tested and careful.

With the Canada for example, the collisions with the fauna represent approximately 1,6% of the whole of the collisions, proportion which can however be considerably higher on certain roads with high traffic and which cross timbered areas, as it is the case in certain parks and natural reserves.

The volume and the speed of the traffic are two factors considered to accentuate the collision risk. … However, birds and mammals die more on the axes of “intermediate” size. That can be explained by the fact why, like the highways or large by-passs broader, are released, conducting and animal see themselves mutually better. But also, one can think that the main roads make more fear with the animals or that they are fewer with their accesses.

Note: Attention, if the animals die less by collision on the great infrastructures, nevertheless in the long run, it is then the parcelling out character of these roads which threatens not only of the individuals, but of the species.

Transport infrastructures

Transport Automobile develops in a way accelerated since the years 1950, generating a road grid increasingly important, dense and inter-connected. Almost all the littoral of planet are skirted by roads or highways (known as " highways of the estuaries " in France), just as the rivers, except on the islands deserted, in the arid zones and/or very mountainous. In the same way the majority of the big cities are encircled of one or more peripheral road belts.

As example, in 1990, France with it was only traversed by 7.000 km of highways and more than 800.000 km of roads. One counted 23.550.000 cars, 4.840.000 commercial vehicles and 7.000 bus and bus, each one of these vehicles traversing on average from 15.000 to 25.000 km/an of which more half in nonurban zone. Being given the speed of growth in the field of transport, these figures probably increased. This highway network strongly contributed to the increase in artificialized surfaces and the fragmentation of the territory (8% of the metropolitan territory according to the IFEN, in 2004, which corresponds to an increase of + 43% of 1982 to 2004, whereas the population had increased only by 11%)
( to be supplemented by the current figures + possibly a graph of the evolution )

Implied species

The near total of the animal species is concerned with the roadkill. The species implied in the road accidents vary obviously according to the areas. The most vulnerable species are however the animals:

  • slow or not very able to avoid the vehicles
  • protected (or believing itself protected) by:
- prickles (Porcupine S, Hedgehog)
- by a carapace (Armadillo S, tortoises terrestrial S, Saurien S)
- by the toxicity of their organization (Clamping plate S, salamander S) But also:
  • the large herbivores which graze on the vast wide ones. In the moderate zones and close to the poles, they must imperatively migrate at the rate/rhythm of the seasons.
  • the large ones and average carnivores (Wolf S, Bear, lynx, Glouton S, Pumas, Ocelot S, wildcats, etc) have generally vast territories of hunting to traverse, and they must sometimes migrate with their preys.
  • the small carnivores (Renard S, Loutre S, Fouine S, Belette S, Putois, etc) which prospect vast territories.
  • animals with vast territory whose habitat strongly regresses. Example:
- the population relic of Bear of the Pyrenees in France, confined on less than 0,1% of her old territory, thus Franska bought as Slovenia was killed over the RN21, whereas it weighed 120 kilograms, on Thursday, August 9, 2007, 1 year after her introduction into the the Pyrenees. This accident took place with a military vehicle, after the ourse was struck by a first vehicle. The military vehicle, a Renault Kangoo, having killed Franska was driven by a warrant officer of the 1st regiment of hussards parachutists, between 6 a.m. and 6 hours 30, to 5 km in the south of Doors on the commune of Viger. This accident took place in full polemic between the inhabitants of the area and the defenders of the reintroduction of the bears in the country, as for the particular behavior of the ourse. This one tended to go down in the plains and to attack sheep of breeding. , . As Slovenia twenty bears are struck each year on roads as in France the Sanglier S and the Cervidé S. the people having organized and taken part in beaten illegal having preceded the accident were not worried, whereas Emmanuel Berthier, prefect of the Hautes-Pyrénées, had explained the illegality of their acts to them.
- the Grizzly confined on less than 2% of its territory in the USA (in the south of Canada),
- the Wolf, the lynx European or American (of which there remain only two important populations in the USA, but which attended all the forests of Maine in Oregon).
  • And all the animals which must cross much roads.
  • Of the semi-domestic animals is done also réguilèrement crushed, in particular of the cats and the dogs.

Note: One does not speak about roadkill for the Flore, since have it considers that the roadkill implies a collision. One can however note that the Fragmentation écopaysagère more largely the increase in the transport infrastructures, are not without consequence on the vegetable biodiversity.

Collision with the insects

There only exists very little of information on the mortality of the Insecte S due to the shocks with the cars or the wounds which turbulences of the fast vehicles can induce on these species.

An evaluation carried out starting from countings made in the area of Fontainebleau in 1990 gave the following results: 60 Billion S (60.10^12) of insects die in a shock against a vehicle each year in France (66, 420 billion for the only area Fontainebleau); and there would be more than 100 T of corpses of insects, larger than those which remain stuck on the vehicles, along our roads.
On does not know which is the share of these insects compared to the total mass of insects which circulate on and above the roads (either on 1,2% of the territory approximately), nor which is the impact on the ecology of the populations of these insects and of those which depend on those for their survival…

JP Chambon, author of this study, as showed as in summer, the period of the day during which the insects are most vulnerable locates in the time slot 13-18 h. and mortality is higher in wooded area than in cultivated and urban zone.

Mortality thus varies according to the traffic, the hour of the day or the night, the density of the populations of insects (and thus agro-ecological context, altitude, microclimates, etc), the level of activity of the insects (variable according to the season, the climate, the place, the luminous Pollution, the moon), and the physiological state of the insects.

This study was not updated (since 1990, the number of roads and the flow of vehicles strongly increased, and certain populations of insects, diurnal butterfly S in particular regressed much). In theory, the impact studies should better study these questions, including for trains of the type TGV, to produce compensatory measures and to better take account of the diversity of the situations (biogeographic, natural environment and color of the roads, nature of the verges and their management, number, speed and type of vehicles, etc), but this problem was dealt with little.

Nevertheless, the data of 1990/91 allowed the following evaluations: Taking into account the evolution of the highway network and car fleet:

  • more 66.000 billion insects can be killed each year per direct collision with the cars in France.
- for this figure it is necessary to add approximately 40 t/an insects killed and projected on the low sides.
- this figure, taking into account the disappearance and of the renewal of the corpses, can be multiplied by 4 or 5 for the year what represents 120 to 200 t/an of animal matter deposited.

JP Chambon points out that one does not know what these figures represent compared to the number and with the mass of the alive insects and, which the surface of the roads where this destruction (6 500 km ²) takes place represents only approximately 1,2% of the whole of French territory (550 000 km ²), registered in 8% of the artificialized/urbanized territory.
Néanmoins, since the cultivated fields became, because of the Pesticide S, uninhabitable for many species of insects, and knowing that the low sides play a big role of “biological Corridor of substitution”, one can think that this mortality is a factor to be considered in term of ecological fragmentation of the territory, the more so as the roads are also ecological barriers for other reasons, studied in addition (See the article on the ecological corridors).

Simple mathematical models show that if displacements of insects were random, existing flows of vehicles are enough to destroy very important populations.

The case of the TGV would also deserve to be studied, because its Effet of blast and the induced Turbulence S are important (300 km/h).

Many other species, whose Amphibien S, Oiseau X and small and large Mammifère S is also victims of “Roadkill”

Collision with the Amphibians

During the migrations towards the place of reproduction, the Clamping plate S, Frog S and triton S undergo true hecatombs, with sometimes thousands of corpses on a few hundred m of roads.
On showed in experiments in addition that the majority of the Amphibians are in addition attracted by the standard lamps (often in edge of roads).

After the exit of the water, sometimes forced by a dryness, mortalities are more discrete, the young Amphibians are very vulnerable (90% quickly will die).
Ceux-ci dies dehydrated in a few minutes on the Bitume or the dry Béton.

Collision with the birds

All the species of birds are concerned, but as private individuals the migrating species and those whose hunting ground is near the roads.

The birds which were born close to a road seem from of “to better learn” the dangers.
Les songbirds tends to move away from the noisy roads.

In fact the raptors night S when they are dazzled by the headlights or luminaries whereas they drive out of night, the least best seem to avoid the vehicles. Thus one observes a strong surmortality of (Chouette S, Hibou X) along the roads near their habitats. They die of collision much more than the diurnal raptors, whereas the vehicles are much rarer on the roads the night. This phenomenon is added to the collisions of birds on the panes and superstructures, of day, but especially of night, because of phenomena generally gathered under the expression " luminous Pollution " The raptors Diurne S find also sometimes victims being attracted by rodents wounded or died on these vast released spaces.

Collision with the mammals

Many data exist concerning large the Gibier S or some species followed by transmitting collars (Ours, Loutre S, lynx). They are at the origin of the creation of the first passages to fauna (écoducs). One misses statistical data for the small mammals (except some studies on the Hérisson S or the squirrel S).

Collision with large fauna

The collision, even at a reasonable speed, with an animal whose weight can exceed 100 kg, can only involve important for the vehicle and body property damages low registers for its occupants.

The operations of avoidance of an animal which crosses the road in front of a vehicle can also be at the origin of accidents.

But apart from the serious accidents, there exists a big number of collisions which are not announced for various reasons whose principal one is the certainty not to be compensated.

It is estimated that the collisions with large fauna are announced only in 50% of the cases. Some advance even the figure of 25%.

Into France, the frequency of the accidents between these three categories is divided as follows:

  • Roe-deers: 50%
  • Wild boars 45%
  • Stags 5%
The gravity of the shock depends on the mass of the animal, the speed of the vehicle, for which it is necessary to add that of the animal if it would run and arrived of face. The kinetic energy grows indeed with the square speed (E=1/2M.V ²).

The probability of meeting depends on several parameters. First of all game populations. However, since the realization of this investigation (1985), the increase in the game populations was strong (multiplied by approximately 4).

But this probability of meeting also depends on the motor vehicle traffic. This one was multiplied by approximately two between 1985 and 2001 (for the national traffic).

Thus the combination of these two factors leads to a potential multiplication by eight of the number of the accidents.

  • In 1985, the estimate of the number of the collisions was of 11000.

  • Into 2001 we can estimate the collisions between vehicles and large fauna at: 100.000
    • And for wild boars alone with 45.000
This number integrates all the collisions without body damage or with body damage.

Thanks to technological advances (Vehicle equipped with the brake ABS, better solidity, etc), the majority of the accidents result only in weak damage and do not cause death or of casualty.

However other accidents are simply due to an operation of avoidance and are not always entered in collisions (they can also be birds, hares, rabbits, dogs, cats, etc This overall estimate remains weak: 4  % approximately of the 2,3 million accidents listed by the insurance companies. Its impact is however perceptible in the public opinion.

Collision with the small mammals

Causes

The causes of the roadkill are many and complex. They are not yet well-known today. One can quote in particular:

  • biological richness and the mobility of the species present

  • the landscape structure and mainly of the structure of the edges
  • the ecological function of the accesses and the presence or biological proximity of corridor
  • the temporal and space distribution
The temporal and spatial distribution of the accidents with fauna is not random, and it is influenced by several factors.

One of these factors is the seasonal distribution of the activities of the animals and their behavior in a given area.

For the mammals, one observes a peak of collisions in spring and in autumn. In spring, this peak perhaps allotted partly to the displacements increased at the time of the migration of inexperienced young people of the previous year and before the low setting. In certain areas, fauna can also be attracted on the roadside for this period by the young vegetation which pushes (in particular in mediums where food is rare) or by the presence of ponds saltworks created by the scrubbing of the salt of thawing of ice (more particularly in Canada and in Scandinavia).

With the autumn, increased displacements of the mammals before wintry time make the latter more exposed to the road collisions. Some also think that the activities of hunting can increase displacements of the animals for this period and caused a peak of the collisions.

Moreover spring and the autumn are the two great seasons of migrations of the majority of the migrating species, one thus observes logically an increase in the roadkill at this period. The collisions also depend on the day laborer activity of the animals. The most harmful periods for the animals are between laying down it and raising it sun, and more particularly in the twilight and the dawn. That can be explained by an increased activity of the animals for these periods, but also by an intensification of the traffic and a reduced visibility.

  • the health condition of the animals
The animals wounded (with hunting, by a predator, or at the time of a preceding collision), patients, weakened by an escape, or poisoned (by Pesticide S for example) have probably more risks to be victims of a collision. The health care centres often find traces of wounds of hunting, even of fresh leads in the flesh of the animals victims of collision (birds in particular). It is one of the reasons which makes that, in the majority of the countries, it is interdict to carry and to consume the meat of animals killed by collision.
  • characteristics of the road
They play certainly a part in the phenomenon of roadkill. The sinuosity, the number of ways, the volume and the speed of the traffic influence the frequency of the accidents. However, there exists only little of specific study on this subject.
  • the volume of the traffic
  • the speed of the vehicles
The rural highway network knew since years 1970 of notable improvements. That makes it possible to circulate with an increased safety and sometimes more quickly. Paradoxically, this progress increases the collision risk with the large animals. The obstacle that they represent emerging in an unforeseen way, the higher mean velocity makes their avoidance difficult and the more detrimental shock. Panels announcing the often existing risk of crossing of animals, but they are not always dissuasive.

  • increase in the distances from the way residence - work

The development of the residences in zone périurbaine, even extremely far away from the work place is a sociological evolution which contributes to an additional increase in this risk. The ways, residence - work and return, are done, the morning and the evening, moments when the large animals move more.

Cost of the roadkill

The costs which the roadkill generates are not easily calculable since not easily estimable. Indeed, the majority of the collisions, even with large fauna are not announced and countings of animals died in edge of the roads cannot take into account the eaten dead animals and those wounded which went to hide to die.

For the collisions with the large herbivores, the physical impact is related on the weight of each species and the frequency of the accidents. This aspect is an approximate indicator of the cost of the accidents. The deer tribe has the mass most raised (more than 100 kg), in front of the wild boars (60 kg). The roe-deers arrive far behind (20 kg).

Estimated cost:

  • Roe-deers 24%
  • Wild boars 64%
  • Stags 12%.

The wild boars, because of their abundance, their compactness and their weight, lead by far to the most important and expensive damage. The vehicle is sometimes completely destroyed. If the owner is not assured any risk, it suffers a high injury. The damage is sometimes body, involving losses in human lives sometimes. (200 motorists per annum in Florida and of the thousands of wounded) Moreover, even when the passengers are not wounded, the psychological shock is important.

The collisions between the vehicles and large fauna have a cost for the community. The figures of the interdepartmental National office of the Road safety give overall for 2002 average unit costs of an accident of 12.000 euros on which the insurances compensate with 6.000 euros height. For the collisions with big game, the mass and speed are divided by two Kinetic energy by eight. The cost would be thus of 1.500 euros and the compensation for 375 euros. By considering that the average costs by accident are of 1500, one can estimate the overall costs at 150 million euros, including 96 million euros for wild boars alone.

Lastly, the roadkill has an undeniable cost for the biodiversity. The number of killed animals represent in the majority of the cases a considerable proportion of the populations.

The cost of the passages to fauna (écoducs) appears justified then.

Responsibility

The collision implies a vehicle and an wild animal. But this last is struck by the vehicle. The vehicle has, in all the cases, a definitely higher speed. As for the fixed obstacles the driver is, owing to lack of control of its vehicle, the person in charge with the legal direction of the accident.

Legislation

In France, in the event of collision with an wild animal, it is necessary to inform immediately is the gendarmerie or the ONCFS (National office of hunting and the wildlife). If the animal can be saved, best is to contact a center of safeguard of the wildlife. For the damage with the vehicles, the wild animals belonging to nobody, contrary to the pets which have an owner, there does not exist system of compensation contrary to the damage on the cultures.

However, if the collision occurred whereas the animal was driven out (the accidents with big game are more frequent in period of hunting), there is a possibility of recourse if the victim is able to prove the action of hunting.

Alternatives

The problem of the roadkill does not have a universal solution, but must be managed on a case-by-case basis. The more the structures suggested will be diversified, the more the fauna which will borrow them could be diversified. However, the first thing to make to limit the collisions is to avoid building transport infrastructures in the forests and other reserves and where they are not inevitably useful (to think of studying the existing infrastructures before building a news of it, for example…)

  • To restore and respect the biological corridors

To try to decrease the impacts of the human growth and the ecological Fragmentation of the territory, several scientists and experts propose to set up, to restore or maintain a network of biological corridors allowing to connect the reserves natural between them.

  • To encourage fauna to circulate in a network protected from natural environments by installations suitable (conservative measures and compensatory)

    • the Fence S
The construction of barriers, like fences, is one of the most current approaches to prevent the collisions with fauna. On the condition of being built well and maintained regularly, the fences for large fauna generally make it possible to reduce the number of accidents, in particular with the large herbivores.
    • passages to fauna
Used with sufficiently high and well maintained fences, the passages to higher or lower fauna (for example, the Crapauduc S or batrachoducs) give the possibility to the animals of avoiding a road, without disturbing their displacements or their migrations. The main features of the passages which can influence their use are dimensions of the structure, its site, cover present in the vicinity, the presence or not of a river and the rate of human activities. To increase the number of passage in tunnel in the hot areas would make it possible to reduce the risk.
    • “cross-pieces”
An alternative solution with the expensive structures is the use of the equivalent of pedestrian crossings, which consist of an opening in the fence, accompanied of control panels informing the motorists of the presence of a “cross-piece” of animals. there are some in various countries, such as for example with the Netherlands.
    • the temporary closing of roads
The migrations of the animal species are seasonal. Also the temporary closing of the roads can it in certain cases protect them. Thus, the batrachians join in spring the water level which saw them being born in order to ensure their reproduction. With this intention, the temporary closing of the roads located on their migration path (in general near ponds or of marsh), makes it possible to prevent that the major part of the population concerned is not destroyed. Several experiments took place in France successfully. It is the case for example the road of the ponds, in the forest of Meudon, closed 3 weeks in April. An adapted indication in general guarantees a good acceptance on behalf of the users.
    • installation of control panels
To try to decrease the collisions, one can pose control panels at the beginning of the roads most concerned with this problem. One can use conventional panels (those of the highway code) but one can also try to sensitize the motorists by using panel of big sizes (silhouette of herbivore for example), luminous or very coloured panels. The studies which evaluated the effectiveness of this measurement are rather rare, mainly because they are complex and expensive. The reaction of the motorists to the permanent panels, even nonconventional, seems insufficient to involve a strong reduction in the number of collisions.
  • To respect the needs for fauna, improvement of the habitat far from the roads
A solution could be to improve the “alternate” habitats and attracting, far away from the roads. However, with the ecological Fragmentation increasing of the landscapes, the hearts of habitats are increasingly rare, increasingly small, and increasingly distant from/to each other. Industrial agriculture and the reduction in the Bocage concentrate flows of animals in a restricted number of places (along the Haie S, of the enherbées Bandes, edges, etc). Moreover, this measurement could apply only to the fauna of the “hearts of habitat”. Part of the typical fauna of the écotone S will always seek to skirt an axis of transport.
  • luminous Device
Studies north American showed that reflectors returning part of the light towards the accesses could decrease animal mortality on the road in “alerting” the mammals being on the point of crossing a road of night whereas a vehicle approaches, but this device loses of its effectiveness at dawn and laying down sun, which are precisely the hours when the collisions with the large animals are most numerous. One tests in 2007 in Taiwan of the lamps with infra-red intended to attract migrating butterflies in a écoduc passing under road main roads.
  • sound Device
The sound devices most known are the whistles with ultrasounds which one can fix at the vehicles (used mainly in Canada). These whistles produce, electrically or by the movement of the air, the sounds (ultrasounds) whose frequency varies, but are not perceptible by the man. These sounds are considered to inform the animals of the approach of the vehicles and to frighten them. One can wonder whether the equipment of all the vehicles would not produce a permanent noise stressing, even unbearable for many species, of which our dogs.
  • To decrease mobility, speed
It is not a solution easy to set up, but it could at least relate to the most significant zones, while waiting for relevant installations (écoducs)

Conclusion and tracks of solutions

The problem of the road collisions with fauna has been known for several years and of many speakers, try to find economically solutions viable and socially to make the roads sourer and to reduce the costs generated by this type of accidents. There does not exist unfortunately universal solution to regulate this complex problem, which varies locally according to several factors. One can summarize the tracks of solutions in the following way:
  • to prevent the presence of animals on the road by the installation of obstacles (but those Ci also contribute to the Fragmentation écopaysagère)
  • to modify the behavior of the animals so as to dissuade them to approach the road;
  • to modify the behavior of the road users;
  • to return the surer cars and roads (infra-red system of detection or by radar, at least for the large animals?)

The evolution of our company is accompanied by the refusal of any risk, was it natural. The large animals, and as private individuals the wild boars, leave the ordered framework of the asepticized urban life. It is imperative to bring back, in many cases, this risk on a level more acceptable for our fellow-citizens but also to better explain to them the constraints of the cohabitation of the townsman in an natural environment, essentially, changing and unforeseeable. On these two points the huntings mediums can bring a contest determining and invaluable.

See too

Internal bonds

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