The ivory gull, classified by the International Union for Conservation of Nature as threatened, is said to be facing a new threat – rising mercury levels in Arctic – because of which there has been a rapid decline in population.
According to a new research by Alex Bond, a former University of Saskatchewan post-doctoral fellow, the population of ivory gulls have declined in number by more than 80 per cent since the 1980s. With only about 500 breeding pairs remaining in Canada, Bond and study co-authors have pegged environmental contaminants as one of the primary reasons behind the decline.
For the research, the team examined museum specimens of breast feathers and measured the mercury burdens of 80 ivory gulls dating from 2007 to as far back as 1877. The findings were startling as far as mercury concentrations were concerned. The researchers found that despite no changes in the gull’s diet, methyl mercury concentrations were 45 times higher than 130 years ago.
Researchers note that ivory gull eggs have the highest mercury content of any Arctic bird, with the Canadian gulls having the highest concentration across the entire species’ range. This is likely because they scavenge marine animal carcasses, which are exposed to high levels of mercury.
“Mercury is an increasing problem for Arctic wildlife as more is emitted by coal power stations and other anthropogenic means,” said Bond. “We wanted to see if the high mercury levels experienced by the gulls was a recent phenomenon, and possibly determine if it was linked to their decline over the past three decades.”
Bond further said that Mercury is accumulating in the ivory gulls about twice as quickly as it is in other Arctic animals and added that if the current trends continue, the bird is likely to be extinct in less than 50 years.
The findings have been published in journal Proceedings of the Royal Society of London B- Biological Sciences and the paper is titled “Rapidly increasing methyl mercury in endangered ivory gull (Pagophila eburnea) feathers over a 130 year record.”