The great tit ( Parus major ), is a small insectivorous bird whose bright yellow plumage can be seen throughout Spain and much of Europe. The abundance and defined character traits exhibited by this passerine made it an ideal study subject for researchers at the University of Antwerp, Belgium, who were trying to find out whether the intake of heavy metals affected the personality of the birds in any way. , as it happens with human beings. Because exposure to these toxic substances produces in people from irritability and extreme fatigue to depression.
Belgian scientists observed and recorded the habits of coal miners living next to the facilities of the Umicore company, a metal smelter and refinery with abundant emissions of lead and cadmium , among other pollutants. The experiment consisted of capturing 250 specimens from different locations – closer and further from the manufacturing facilities – and examining how they behaved in the laboratory. And so they discovered that the chickadees with greater contact with heavy metals, as they were able to verify by analyzing the chemical composition of their eggs and feathers, were more inactive. The lead and cadmium had “quenched” his natural propensity to be curious , to explore the environment.
Get out of my nest!
But it was not the only personality change detected by experts at the University of Antwerp. In the second phase of the study, they marked the captured specimens and returned them to their original environment, where they again observed their habits and reactions not only to natural stimuli, but also to others induced by scientists, such as the introduction of a bird. stuffed animals in their nests or the reproduction of recorded songs to induce them to believe that a competitor was haunting them. Thus they were able to verify that the most aggressive males in front of the lure were precisely those that lived closest to the Umicore facilities. In a similar way, the females neighboring the refinery were the ones that showed the most protective behavior in their nests.
In short: lead and cadmium were making charcoal burners both more decayed and irritable. And this character disorder, according to the researchers, makes them more vulnerable to their predators .
On a plastic diet
Unfortunately, metals are not the only food threat to birds. Other recent reports indicate, for example, that more than 80% of marine species have introduced plastic – bags, bottle caps, etc. – into their usual diet, and that the percentage will skyrocket to 99% by 2050. It seems be, according to a study published in 2016, that they mistake it for food due to the smell: when decomposing waste in the sea, microbes generate a fragrant substance called dimethyl sulfide. And by ingesting the plastic, birds can suffer intestinal obstruction, poisoning or malnutrition.
Image credit: a great tit and a blue tit in dispute./iStock.
