10,000 Birds

Yellow-billed Magpies Pica nuttalli
Panoche Valley, California. 10 January 2007

Very similar to - and very closely related to - the larger Black-billed Magpie Pica pica, the striking Yellow-billed Magpie is exclusive and endemic to California, west of Sierra Nevada. Its range includes Sacramento and San Joaquin valley floors and foothills, and valleys of Coast Ranges from San Francisco Bay south to Santa Barbara County, though habitat loss and exposure to poison from ground squirrel control efforts have led to population declines over parts of its historical range [Audubon watchlist].

Though there is some debate as to whether all the pied Magpie forms should be ‘lumped’ (except for the Korean P. p. sericea which appears to be a separate species), studies combining fossil evidence (Miller & Bowman, 1956) and paleobiogeographical considerations with the molecular data indicates that the Yellow-billed Magpie’s ancestors became isolated in California quite soon after the ancestral magpies colonized North America (which probably happened some 3-4 million years ago) due to early ice ages and the ongoing uplift of the Sierra Nevada, but that during interglacials there occurred some gene flow between the Yellow- and Black-billed magpies until reproductive isolation was fully achieved in the Pleistocene.

Far more wary than eg Black-billed Magpies in the UK or Asia, I’ve tried (and failed) on many previous occasions to get decent photographs of this species before finding a few approachable individuals in a flock of about fifteen in the Panoche Valley. Small flocks routinely forage on the ground, mainly eating insects, especially grasshoppers, but also carrion, acorns and fruit in fall and winter - and these birds were doing exactly that, foraging noisily in a pasture with a few horses and oak trees.

All photos copyright Charlie Moores