Migration: Why did the Osprey leave Mono Lake?

This post was written by Bryce Tiernan, 2013 Mono Lake Intern.

With a fresh dusting of snow covering the Sierra Nevada, it seems like an appropriate time to talk about migration. More specifically: Osprey migration. While Mono Lake is probably most known for its nesting California Gulls, there is an ever-growing population of Osprey that nest at Mono Lake every summer.

Osprey are a relatively recent addition to the Mono Basin, with the first nesting pair sighted in 1985 and the first confirmed nesting success—two chicks—coming a few years later in 1989. Since then the Mono Lake population has blossomed, with a recorded high of ten nesting pairs this past summer!

Now, with the summer chicks having fledged over a month ago and the nights cooling off, we are seeing the Osprey leave Mono Lake and venture to warmer climates. Like any sensible creature, the Osprey are off to Mexico and beyond for the winter!

On September 4, 2013 one of the adult female birds outfitted with a GPS transmitter left Mono Lake and began migrating south. Her last known location was inland from the Gulf of Mexico California coastline, north of Mazatlan. In recent years researchers at Mono Lake have been able to band the chicks hatched here and outfit some birds, like this female, with a GPS tracker. This research is being made possible with funding from the Mono Basin Bird Chautauqua Jeff Maurer Research Grant, the Bodie Foundation, and private donations accepted through the Bodie Foundation.

Aside from the Osprey that nest at Mono Lake leaving for the winter, Osprey from farther north are also migrating through the Mono Basin. This past week here at the Mono Lake Committee, we got to participate in the rescue of one such Osprey. The Osprey had stopped at Grant Lake Reservoir to fish and accidentally ate a fish that had already been caught. The bird had ingested a hook and line along with its fish and then had become tangled in the line and was unable to fly. The bird was rescued by Interpretive Ranger Dave Marquart and taken to Eastern Sierra Wildlife Care for treatment. The Osprey was able to make a terrific recovery and was re-released at Grant Lake Reservoir to continue its migration south.