Scientists from the University of Castilla-La Mancha, the Higher Council for Scientific Research, the University of Coimbra (Portugal) and the Autonomous University of Madrid have drawn up a series of maps that record the risk of exposure of wildlife to certain environmental pollutants like lead . Specifically, they analyzed the lead in the blood of 691 specimens of griffon vultures ( Gyps fulvus ) captured by environmental experts from Aragon between 2008 and 2012.
According to Patricia Mateo Tomás, a researcher at the University of Coimbra and main author of the work, which appears on the cover of the journal Proceedings of the Royal Society , they have detected high levels of lead (> 200 ng / ml) in the blood of 45% of the 691 griffon vultures studied. Their tests reveal that this metal would come from at least two different sources. On the one hand, the geological lead that is naturally present in the soil, which would explain the high basal levels in the blood of scavengers, while the most extreme values (> 500 ng / ml), detected in the 6 % of the vultures could come from lead ammunition, used mainly in hunting larger game .
The griffon vulture is a widely distributed scavenger in the world, situated at the top of the food chain and feeding only on dead animals . It is a bird specialized in locating carrion, remains to which it manages to access to consume them very quickly. This fact makes the vulture a very valuable indicator to identify the effects of environmental pollutants such as lead on other less abundant and threatened species and even on humans. Lead is one of the most toxic heavy metals for humans and wildlife . Although its presence in our environment has been reduced after the ban in many countries of the use of leaded gasoline, this metal is still present in the environment.
The griffon vulture population in Aragon is estimated at more than 5,000 breeding pairs , which represents around 21% of the population of this species in Spain and 15% in Europe. The experts made predictions about the risk of exposure to lead in these birds, using wing tags with their biological characteristics and the habitat near their breeding colonies and the feeders they frequented. Vultures absorb the lead present in the tissues of domestic and wild animals that they consume , coming from the soil on which they feed and, additionally, the lead from the ammunition after consuming the remains of hunting ungulates such as deer or wild boar that remain in the field after its capture. In fact, in Spain and in many other places, a large part of the carrion consumed by vultures is residues of human activities such as livestock or hunting, whose meat is also consumed by humans.
Lead affects many animal species, especially large raptors, affects their demographics and even causes the death of some individuals. To mitigate the impact of this and other similar risks associated with the presence of pollutants in the natural environment, it is necessary to know not only their sources, but also their spatio-temporal distribution. Vultures, like other species high in the food chain, are good sentinels for environmental contamination, and their potential as indicators may be even greater because they feed on animals that can also be consumed by humans. These maps can help environmental managers to delineate the areas and times of the year most at risk for lead exposure.
