Daniel A. Airola; Conservation Research and Planning;; Lily A. Douglas, Layla Airola

The Yellow-billed Magpie (Pica nuttalli) declined precipitously after West Nile virus arrived in the early 2000s and has not recovered. Most ecological work on the species has occurred in oak woodlands in California's Coast Ranges. Urban populations, some of which are sizable, have received little attention. In 2020, we studied breeding colonies in six Sacramento parks and in 2021 expanded to 43 sites, detecting 827 magpies. Fledgling counts yielded reproductive rates similar to those observed near the coast before arrival of West Nile virus, suggesting that the virus is not currently affecting nestling survival. Magpies nested in the upper canopy of a wide variety of large native and non-native trees. They foraged preferentially in low herbaceous habitat, consisting of irrigated turf and unirrigated mowed or grazed annual grassland. Colony size was strongly related to the amount of low herbaceous foraging habitat within 0.5 km of flowing water, suggesting West Nile virus effects may be low in remaining occupied areas. Results suggest that >4 ha of low herbaceous habitat near flowing water is needed to support a small nesting colony. Management for urban magpies should focus on retaining and managing herbaceous habitat through mowing or grazing in areas near large trees and flowing water.

Bird Ecology and Conservation  InPerson Presentation