Interagency collaboration continues to protect California Gull nesting habitat at Mono Lake

On Saturday, September 16, an intrepid group of Mono Lake Volunteers, Mono Lake Committee staff, and Inyo National Forest employees teamed up to pull invasive weeds on Twain Islet. Twain is key nesting habitat for California Gulls, and in the past decade invasive species have started negatively impacting the gulls’ nesting productivity.

One shrub in particular, Bassia hyssopifolia, is extremely harmful because it leaves behind a large dry plant skeleton that stays rooted in place for years. The Bassia shrubs interlock with each other and with previous years’ skeletons as they grow, eventually forming an impenetrable, waist-deep thicket. Several years ago this thicket covered a large percentage of Twain Islet, significantly reducing the ground area available for gulls to build nests on, so the Inyo National Forest, with help from the Mono Lake Committee, used prescribed fire to clear the Bassia in February 2020. Since that prescribed burn, we’ve gone out to Twain about once per year to pull Bassia plants by hand in order to keep them from proliferating.

Post author Juniper Bishop, Bartshe Miller, and Eric Rios-Bretado enjoying the 20-minute boat ride from Mono Lake’s west shore out to Twain Islet. Photo by Fiona Travers.

This summer the invasive weeds did very well for themselves, which makes sense given the abundance of precipitation we’ve had. Committee staff have been monitoring the Bassia situation on Twain Islet for several years, and we were surprised how large and abundant the invasive weeds were this year when we went out to check on things in early September. Luckily, the majority of the plants had not gone to seed yet, giving us time to respond and treat the infestation. The Committee immediately organized a group to go out the next week and have a weed-pulling party.

Invasive Bassia hyssopifolia weeds grew well on Twain Islet during this wet year, leading to the hand-pulling effor to remove them. Photo by Fiona Travers.

Getting out to Twain Islet is a 20-minute boat ride from the lake’s west shore. Traveling by boat toward the islands we passed hundreds of Eared Grebes, Red-necked Phalaropes, and California Gulls. Passing slowly along the north shore of Negit Island, we could see the lakebottom under the water—the passage was less than ten feet deep, making it easy to imagine how the landbridge can connect Negit to the mainland. The Negit Islets extend out to the northeast of Negit proper, with names such as Java, Pancake, and Krakatoa. Twain is the largest of these islets and became the primary site for the California Gull nesting colony after the Negit Island colony was abandoned in 1982. With the lake fluctuating at dangerously low levels for the past five decades, gulls haven’t returned to Negit in large numbers, and more than half of the gulls at Mono Lake continue to nest on Twain Islet. However, from 2016 to 2019, the gulls’ nesting population was in decline, in conjunction with the spread of Bassia across the islets. After the 2020 prescribed burn, the Bassia on Twain was successfully removed, and the number of nests bounced back dramatically.

Uprooted Bassia plants were thrown into Mono Lake to effectively remove them from the nesting habitat. Photo by Fiona Travers.

This balmy September morning we had seven people willing to help fight Bassia and protect gull nesting habitat, so we had to make two boat trips to Twain to get everyone out there. Treating Bassia is not light work—the bushes can be three feet tall, with stems more than an inch thick, so the larger plants are challenging to pull out of the soil. Then we haul every plant we remove down to the lakeshore and throw them in the water. The ground there is raw volcanic rock covered in tufa, making for very unstable footing, especially when you’re wrestling 30 pounds of spiky shrubbery along the way. And when you need a shaded water break, the nearest tree is miles away—so forget about escaping the bright sun! In spite of my gripes, though, the whole crew that went out on September 16th worked very hard and accomplished a lot. It was great to collaborate with Inyo staff and the Mono Lake Volunteers as a head start to National Public Lands Day, which is tomorrow!

The Inyo has many events planned in the Mono Basin for National Public Lands Day, from outdoor yoga in the morning to a night sky program in the evening. Come on out to learn more about the organizations that are helping steward the Mono Basin National Forest Scenic Area, volunteer to do some trail maintenance in Lundy Canyon, or go on a forest bathing walk.

Top photo by Bartshe Miller.