The reduction in the number of Spanish populations of red kites accused of poisoning by insecticides. As found by the team of ornithologists, such cases occur often enough to undermine the welfare of small breeding groups. In an article for the journal PNAS , the researchers notedthat similar challenges are faced by thousands of species across the planet, however, to link their decline with specific factor rarely.
Many wild animals are suffering from poisoning by pesticides, veterinary drugs and other chemical compounds that are produced and used by people. For example, several species of Indian vultures were on the verge of extinction after treatment of cows began to apply anti-inflammatory drug diclofenac. And extremely rare California condors (Gymnogyps californianus) are ill or die after swallowing pieces of lead bullets, which remain after the hunt.
However, to link individual cases of poisoning with the downsizing of the entire species is not always possible. The fact that their accounting is rarely conducted systematically and on a fairly large area. As a result, scientists can only make assumptions, which complicates the environmental work.
A team of ornithologists led by Patricia MATEO-tomás (Patricia Mateo-Tomas) from the University of Oviedo decided to find out how the poisoning effect on the wellbeing of the Spanish population of red kites (Milvus Milvus). In the past, these birds were widespread in Europe and North Africa, but in the twentieth century have become rare everywhere. Spain is considered one of the main strongholds of the species: here the nest for about two thousand couples.
Comparing the data of the national census of the population of red kites in 1994 and 2014, the researchers found that during this period the number of breeding pairs in Spain decreased by 31-43 percent. In this case, from 1995 to 2013 was recorded 1075 poisoning of these birds. Toxicological examination was carried out for 657 of them. She revealed that more than 82 percent of the time the kites were etched two highly toxic insecticides — aldicarb and carbofuran. In the EU they are banned since 2003 and 2007 respectively, however, their illegal use continues, including the killing of stray dogs and other animals.
The analysis showed that the poisoning does lead to a decline in the population of red kites. The more such cases have occurred in a particular area, the faster it decreased the number of breeding pairs. Relatively large groups of kites could withstand this pressure and remain stable, but a small and isolated quickly died out. The authors believe that the poisoning should be considered the main factor responsible for the disappearance of the species in Spain.