Deslauriers Island, which is part of the Varennes Islands archipelago, is very small, but it is very interesting since it is the open-air laboratory of university researchers from UQAM and McGill. On site, they study a sentinel bird, the ring-billed gull, which is the barometer of changes in an ecosystem.
According to the ornithological site IBA Canada and data from Environment Canada, there are three times fewer nesting pairs remaining on Deslauriers Island than 20 years ago, when more than 50,000 pairs were recorded there, or more than 100,000 gulls.
This decrease can be explained by the incessant pounding of ships on the river, slowly but inexorably eating away at the island of only one square kilometer. Environment Canada data indicates that in 10 years, it would have lost a third of its surface area, which means that if nothing is done, it is doomed to disappear, just as was the case for Bellegarde Island. , which was a little further north.
Another problem is the proliferation of an invasive plant there, the phragmites or exotic common reed, which makes nesting difficult for ring-billed gulls. If it is not possible for this species to settle in this location, researchers fear that they could establish themselves in nearby urban areas, which would cause inconvenience linked to screaming and droppings.
Toxic compounds
This open-air laboratory is therefore rapidly diminishing, to the great dismay of university researchers who attach small GPS devices to the gulls and take blood samples in order to understand the effects of certain pollutants on the brains of these mammals.
Through their research, they discovered that pollutants linked to flame retardants are found in the systems of these birds, i.e. compounds that are added to a host of consumer products containing plastic, foam or synthetic fabrics. . These compounds are mostly persistent, bioaccumulative and toxic. They accumulate in birds’ tissues and disrupt the functioning of their thyroid hormones.
These flame retardants were gradually banned until 2015, but there are still thousands of tonnes in circulation around the world, integrated into furniture, cars, computers or homes. In addition, these compounds have been replaced by new families of flame retardants for which it will take years to know the environmental impacts on birds. And eventually, they might even act as a warning siren for the human population.
