Invasive plant overgrowing gulls’ Mono Lake nesting grounds
LEE VINING, Calif. (AP) — Thousands of California gulls that return each year to Mono Lake in the eastern Sierra Nevada are increasingly finding their nesting grounds crowded out by an invasive bush species.
The 11,075 nests counted this year on the lake’s islets were the fewest recorded over 34 years of study, the Los Angeles Times reported this week.
About 32,000 nests were counted in the early 1990s. The number was in gradual decline since 2004 and became a steep decline since 2016.
Lying east of Yosemite National Park, the extremely salty and alkaline waters of million-year-old Mono Lake sprawl over 65 square miles (168.3 square kilometers). It is best known for its calcium-carbonate “tufa towers,” which are spires formed by the interaction of freshwater springs and the alkaline water, but the lake also serves a huge number of birds.
The cause of the gulls’ nesting problem is a Eurasian bush known as five-horn smotherweed that grows waist-high. Although it is an annual, its spider-like carcasses last for years, the Times reported.
The bush rapidly began taking over the islets in 2016 and 70% of the gulls’ breeding grounds “are now big nasty patches of weeds casting off thousands of sticky seeds that attach to your shoelaces, shirts and pants,” biologist Kristie Nelson told the newspaper.
Geoffrey McQuilkin, executive director of the nonprofit Mono Lake Committee, said herbicide can’t be used because of the many sensitive native plants and animals on the islets, pulling all the invasive bushes out by hand would be an enormous task that wouldn’t have permanent results.
“That leaves an unprecedented controlled burn operation as our best bet,” he said.
So far, however, a burn has been postponed for three consecutive years because of extreme fire seasons, winter storm systems and deep snowpack.
The lake’s islets become off-limits in April for the five-month nesting season.