32 years of California Gull research at Mono LakeSeptember 3rd, 2014 by Mono Lake Committee Staff
This post was written by Sandra Noll, Birding Intern in 2014, 2015, & 2016.
The nesting population of California Gulls at Mono Lake represents a significant percentage of the state’s total population of these birds. This year marks the 32nd year of research at Mono Lake under the aegis of Point Blue Conservation Science, providing a reflection of Mono Lake’s overall health in a rare long-term study of inestimable value.
Each year the population size and reproductive success of California Gulls at Mono Lake are measured. These population parameters are obtained in three basic assessments: 1) a count of all nests in May; 2) chick count, physical assessment, and banding in sample plots in July; and 3) a chick mortality count in September (in such a huge, dense colony, not all chicks survive to fledging).
The mean number of young successfully fledged per breeding pair is used as a measure of annual productivity, a reliable determination of the health of the Mono Lake population of California Gulls. Ornithological researchers Kristie Nelson and Ann Greiner have led the study for the past ten years.
As Mono Lake Committee Birding Interns, my partner Erv Nichols and I were eager to participate in May’s nest count. I quote Charles Dickens in summarizing the actual experience: “It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity….” The quote is best understood in the context of our being on the cusp of our seventh decade—perhaps an age of wisdom and foolishness given the rigors of this assignment.
Our study team was based on the islet Krakatoa for ready access to gull nesting sites. To reach the islet, we drove around Black Point, then hiked a half mile or so through volcanic gravel, greasewood thickets, and an alkali mud flat to rendezvous with Kristie in a small skiff for the final approach. The day’s weather began with a cold drizzle followed by an afternoon of warm sunshine for our first counts and ended with cold winds and rain. Subsequent days were sunny with late afternoon wind and cold nights; a welcome pattern for those who had endured much harsher conditions on previous surveys.
Krakatoa, named for its supportive role in the 1953 movie Fair Wind To Java, is indeed a volcanic island but had no cone before Hollywood’s intervention. The old movie set provided a framework for our no-frills base camp—remnants of the chicken-wire-and-stucco volcanic cone built over this framework are still visible. An open-air toilet was accessed across, over and behind 40 grueling yards of rock, that arduous journey being “the worst of times.”
The “best of times” centered around team members: our intrepid leader, Kristie and her longtime colleague, Ann, along with Zach Michelson and Teague Scott. After each long work day, Zach and Teague provided lively tunes on banjo and guitar while Ann and Kristie whipped up nourishing and tasty meals. A skilled and knowledgeable crew!
We were advised to anticipate an “other-worldly experience of a lifetime” while staying on Krakatoa for the nest count and the experience fully met expectations. Spectacular views were highlighted by a backdrop of the snow-capped Sierra. Neighboring nesting islets (Norway, Little Tahiti, Twain, Pancake, Coyote) appeared stark, surreal, and lunar-like as we walked across them, counting nests, in the midday sun but were bathed in glowing colors at sunrise and sunset.
Isolated in the middle of the lake we felt little kinship to those on shore. Time warped. Our world was sun and storm, the moon and Venus in a cobalt sky at 4:00am, breathtaking sunrises and the constant scream of gulls. At workday’s end there was conversation, music, acrobatic Violet-green Swallows catching wind-borne feathers (prized nesting material) mid-air, and time to quietly marvel at the universe and our small place in it.
We did not go to Krakatoa for the challenge or the scenery, however, we went to assist with the annual count of California Gull nests. Each day we traveled to different islets by boat, tying up in areas of low gull density to minimize disturbance. Once ashore the team lined up at ten-foot intervals. One “lead” walked the shore, while another team member walked the opposite side using a line of dilute, water-soluble paint to mark an interior border as we moved forward counting nests. Everyone moved forward as quickly as possible with count-clicker in one hand, squirt-bottle in the other, paint-marking each counted nest to prevent redundant counting. At the end of a sweep the group pivoted and realigned along the interior border making additional sweeps as needed. When the line encountered fenced sample plots the leaders made a dual count of both nests and clutch size.
It sounds easy and it might be in an open field, but islets aren’t uniform—many have odd shapes, fiords and/or steep ridges—presenting logistical challenges. Everyone dealt with uneven terrain, brush, chasms, tufa groves, and ridges as best as we could while maintaining the count and the line’s integrity. On small or particularly steep islets, fewer counters covered the area in one sweep.
Some gulls build discrete nests of twigs and feathers, others lay an egg in a bare dirt depression. Some nest under bushes, others in the open. Average clutch size is two eggs although there were many single- and triple-egg nests. I saw one nest with five eggs! Some gulls densely crowd into small areas while others choose roomy rookeries on islets so tiny as to require counting from the boat. I couldn’t help but wonder if there is a hierarchy in the group; some sort of status for prime nest sites. And how do the benefits of colony nesting mitigate the drawbacks? As usual, the more I observe and learn, the more questions come to mind.
In an unusual occurrence, a dead gull was found that had been banded in 1988, making it 26 years old. It was interesting to think how many trips it had made across the Sierra and back and how many miles of Pacific Ocean it had flown before returning to its natal home of Mono Lake to die. It ties the previous old age record for a Mono Lake California Gull.
Our combined 2014 nest count for all Mono Lake was 19,937 reflecting 39,874 nesting birds. Kristie and Ann will be making a complete report and interpretation of data this fall. Erv and I feel extremely fortunate to have shared this experience and assisted in their important work. Candidly, however, we are also grateful that the following phase, the rigorous chick assessment and banding, featured a younger crew. We who remain safely on shore salute you!
Note from Kristie: 825 gull chicks were banded in the plots in July 2014, suggesting that average chick production was slightly above the long-term average (we have yet to assess the post-banding mortality rate, yet this is typically a small percentage). This is good news, as Mono Lake California Gull productivity has been below average since 2009.
Despite Mono Lake being packed with brine shrimp and alkali flies in late summer, most juvenile gulls migrate to the Pacific coast in early fall. Fledged, color-banded gulls from Mono Lake have already been observed from locations ranging from Crowley Lake (southeast of Mammoth Lakes) to at least two birds at Southeast Farallon National Wildlife Refuge, where many have been seen in previous years.