Animal welfare officers said the seagulls found drowned at Wistlandpound Reservoir, near Combe Martin, England, may have been intoxicated from the formic acid released by ingesting flying ants, The Sun reported Wednesday.
The officers said seagulls have been known to fly into cars and buildings while intoxicated on the acid, which acts like alcohol in their digestive systems.
A spokesman for South West Water said tests have been carried out on the reservoir and the water has been determined to be safe.
"We have carried out water quality tests and algae levels are low," the spokesman said. "We believe this is a phenomenon of the current environmental conditions and not anything to do with our reservoirs."