New Wintering Songbirds On SEFI

March 10, 2021

As songbirds migrate they make multiple stopovers along the way to rest and refuel. The Farallones are a popular stopover site during fall migration as evidenced by the refuge being recently recognized as #1 on a list of National Wildlife Refuges ranked by number of bird species. In addition, last fall was an above average year for most of our common migrating species, and November was well above average for migrating sparrows. Sometimes on their southward migration, if individuals find an area with enough resources, they may choose to abbreviate their travels and stay the whole winter. The normal suite of wintering song birds on the Farallones include Black Phoebes, Fox Sparrows, White-crowned Sparrows, Golden-crowned Sparrows, and Western Meadowlarks but this year we had a few extra visiting sparrows. Although none of these species are unusual wintering songbirds on the mainland, we have never had Savannah Sparrows, Lincoln’s Sparrows, or Spotted Towhees decide to overwinter on the island.

Savannah Sparrows breed in the northern half of the US, across all of Canada and up to slightly within the arctic circle. They winter in the southern half of the US, Cuba and through nearly all of Mexico. Migrants can appear in the area any time between late August and early November.

Lincoln’s Sparrows breed from Alaska, across Canada to the Hudson Bay and Nova Scotia, and winter along the west coast, in parts of Texas and the southwest, and nearly the entirety of Mexico. Fall migration peaks on the central CA coast in late September to early October.

Spotted Towhee occupy the west coast from Vancouver island to northern Baja California and their wintering range extends into Texas and Northern Mexico. Their breeding range extends to the eastern Dakotas and into the Great Plains in Southern Canada. Their peak fall migration on the central CA coast is typically in late September and early October.

There are a lot of reasons that songbirds may choose to shorten their migration but it is always a tradeoff between reducing the energy expenditure of a continued migration and the availability of resources and cover on their wintering grounds. Typically the island is not a particularly appealing habitat for these species, but this year COVID-19 prevented USFWS from conducting its usual invasive plant management on the island, and there is a lot of available food and cover. Considering their success wintering on the island this year, it will be interesting to see if these species try again in the coming years.