THE IMPACTS OF LINEAR INFRASTRUCTURES ON BIODIVERSITY


Roads represent an important cause of mortality for many species and a threat for the conservation of biodiversity. This phenomenon is constantly increasing in recent years, and must not be underestimated due to the following reasons:

-roads represent a disturbance factor and cause the reduction and fragmentation of habitats;
-accidents with wildlife can have a significant impact on the survival of some species, especially the ones that are at risk of extinction;
-roads can represent an important barrier for the movements of many wildlife species, thus reducing the interchange within and between populations;

Animal-vehicle collisions (AVC) produce considerable costs in road traffic due to human fatalities as well as ecological and economic losses.

Reliable data on economic and ecological costs is available to date for only a few European countries over the past three decades (cf. Langbein et al., 2011). For the year 1996 alone, in Europe 500,000 collisions with ungulates, 300 human fatalities and an economic loss of ca. one billion US dollars were estimated by Bruinderink and Hazebroek (1996). Two decades later, 263,000 officially reported WVC and an economic loss of almost 0.7 billion Euros were reported for Germany alone (GDV, 2017). The total damage in Europe overall can therefore be assumed to be far larger than in 1996. At present, a total of 800,000 AVC with ungulates is estimated for Germany, given that likely more than two-thirds of all collisions remain unreported, as reported for the US and Canada (Huijser and Kociolek, 2008; Snow et al., 2015; Hesse and Rea, 2016) (Reported from Benten et al (2018): Wildlife Warning reflectors’Potential to mitigate wildlife-vehicle collisions-A review on the evaluation methods. Front. Ecol. Evol., 12 April 2018 HO).

Besides direct mortality on roads, all the target species are affected in one way or another by the problem of increasing road infrastructures and traffic. For some (like in Italy and Greece) the presence of roads represents more a cause of fragmentation between different areas, whereas in other areas (e.g. Spain) the direct mortality on roads is the most impacting factor.

 

 

For each Italian Province it has been estimated that at least 15.000 animals are killed on the roads each year, summing up to 1,5 mln animals each year at national level. However, this number is purely indicative because the phenomenon is not yet accurately and systematically monitored.

Besides the direct mortality the presence of roads in Abruzzo also represents an important cause of habitat fragmentation. One of the main problems for bears, as stated in PATOM is that the migration into new areas is a big challenge due to the presence of main roads, motorways and other infrastructures that cross the corridors leading to other potential territories. One major barrier is represented by the National Road SS17-SS5 (Sulmona-Roccaraso), which separates the range of PNALM and PNM.

 

In Spain there are no official sources, but a study published in 2015 by Antonio Sáez-de-Santa-María and Jose L. Tellería in the European Journal of Wildlife Research estimates that between 2006 and 2012 in Spain 74.600 animal-vehicle collisions have occurred, for an average of 10.657 casualties per year.

 

For Greece besides the database kept by the Motorway Company EGNATIA ODOS SA on its own highway network there is no national data base available. In 2015 and 2016 this company recorded collisions with an average of 282 wild animals and 235 domestic animals/livestock on the motorway track.

The highway also has a negative impact on the bear population because it separates two important mountain ranges where this species occurs, and therefore represents an important obstacle for the movement of the animals. Telemetry data from 19 radio-tagged bears and 58.373 radiolocations (under LIFE ARCKAS project LIFE09NAT/GR/000333) have shown that the bear proof fence seems to have influenced the bear’s activity areas along the highway corridor. In particular, after the installation of the new fence core activity areas seem to appear at a longer distance from the highway route corridor.

 

In Romania no general data about the amount of AVC are available because no official records are kept. In the next period (10 years) it is proposed to build a new motorway in the project implementation area, so that this motorway along with the adjacent national roads would have a negative role in maintaining the connectivity of the natural habitats of the bear population in Romania.

This project is funded with the contribution of the LIFE programme of the European Union

Photos: Manuel Moral Castro; Haritakis Papaioanou, Balkan Chamois Society, Pindos, Valentino Mastrella/PNALM, Angelina Iannarelli/PNALM