The closer to the road, the lower species diversity of birds — at least in the UK. To such conclusion the Cambridge ornithologists, analyzing data on 75 species of birds. It turned out that a rare, small and migratory species tend not to settle near roads. Their place is occupied by more common species that impoverishes the whole community. In his article for the journal Nature Communications , the authors urge , to take action that will reduce the negative impact of roads on natural ecosystems.
The Earth’s surface covers more than 64 million kilometers of roads. Experts predict that in the future this figure will only grow. This is a serious threat to biodiversity, because the road is a source of noise and pollution, and the cause of death of animals under the wheels of cars. Unfortunately, the impact of the transport network on the natural ecosystems are not well understood. Moreover, only a few countries consider roads as a source of danger to the environment.
In the UK road network is one of the most dense in the world: 80 percent of the country is less than a mile from the nearest highway.
A team of ornithologists led by Sophia cook (Sophia C. Cooke) from Cambridge University, decided to figure out how proximity to highways affects the number of 75 species of British birds.
Experts analyzed data on the species diversity of birds collected by volunteers during a national census in 2012-2014 on 2033 of land of one square kilometer. They were compared with proximity to roads of different types, located within five kilometers. The authors have taken into account other factors that could affect bird populations, for example, the density of the human population, the proportion and absolute area of arable land, forest cover and air temperature and rainfall.
The proximity of roads affected the number of 63 percent of the studied bird species. Population 53 percent of them were smaller in areas with more dense road network. Thus, when the analysis left only to major motorways, this proportion had increased to 81 percent. Stronger than others from the vicinity of the roads was suffering from a rare, small and migratory birds.
It is interesting that some birds avoided the main highways, but felt good in the vicinity of the secondary. This indicates that around the roads can be formed in the edge habitat, favourable to certain species, however, close to major roads noise and pollution is so high that outweigh its benefits.
The closer to the road was the plot, the lower was the species diversity of birds on it. However, their total number of trails in the area remained high due to the replacement of sensitive rare species (such as meadow Pipit (Anthus pratensis)) is more common, tolerant to the presence of humans, noise and other negative factors (including, for example, common bullfinch (Pyrrhula pyrrhula)). In other words, around the roads formed a lean homogeneous community of birds.
The authors have not found relations between changes in the number of individual species throughout the country and their ability to settle near roads. They attribute this to the fact that a full population census of the birds began only in the 1970s, and since the length of British roads has increased by less than twenty-five percent. Probably, the decrease in the number of species that were not able to adapt to the proximity of highways, occurred in the middle of the last century.
Researchers are encouraged to develop approaches that will reduce the negative effect of roads on the environment. This primarily applies to noise pollution. Special attention should be paid to protected areas: 41 percent of their area in the UK are within 700 metres from the road. The results of the analysis are important for countries where the road network continues to grow rapidly.
According to a recent study, the development of the road network is an important threat to tigers (Panthera tigris). 24 thousand kilometers of roads built in Asia by 2050, reduce the numbers of these raptors by 20 percent, and will increase the risk of poaching. Especially dangerous is actively developing project of China “One belt and one road”.
Sergey Knee High