Seagull Droppings Impacting the Environment

With 1.4 million seagulls feeding at landfills across North America, Duke University researchers are expressing concern for the resulting waste (seagull droppings) and its impact on nearby water sources.

Seagulls flock to a landfill to find easy sources of food. A study finds their nutrient-rich droppings may cause major water-quality problems in nearby lakes and reservoirs. (Source: Scott Winton/Duke)

"We estimate these gulls transport and deposit an extra 240 tons of nitrogen and 39 tons of phosphorus into nearby lakes or reservoirs in North America each year through their feces," said lead author Scott Winton, a 2016 doctoral graduate of Duke's Nicholas School of the Environment.

According to researchers, the nutrient-rich droppings can result in algal blooms capable of robbing surface waters of the oxygen needed to maintain aquatic life (called eutrophication).

The algal blooms can have both economic and ecological consequences — cost to local governments and the affected fishing industry.

"It costs local U.S. governments an estimated $100 million a year in nutrient offset credits to address or prevent the problem and maintain nutrient levels at or below the total maximum daily load threshold for water quality," said Mark River, a doctoral student at Duke's Nicholas School, who conducted the research with Winton.

Conducting research at landfills in close proximity to two drinking water reserves in North Carolina (Jordan Lake and Falls Lake), researchers believe the problem and its consequences may be greater than originally thought.

"The idea that gull feces can be a major water quality problem may sound comical — until you look at data from an individual lake," Winton said. "In Jordan Lake, for instance, we found that a local flock of 49,000 ring-billed gulls deposit landfill feces, containing nearly 1.2 tons of phosphorus, into the lake annually."

Some solutions to the problem, according to researchers, include reducing seagull populations, reducing the size of open landfills and covering exposed trash more quickly.

"There's a decent history of local governments implementing gull management at landfills because of fears about airplane strikes or because of the nuisance factor to nearby communities," Winton said. "It might be cost-effective to pursue some of these non-lethal mitigation methods to reduce nutrient loading, as well."

The findings are published in the journal Water Research.