Western Bluebird Sialia mexicana Swainson       Field Guide IDs: NG-346; G-250; PW-pl 48; AW-pl 500; AM(III)-46 Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy F I: ? DAYS ALTRICIAL 2 feet - 50 feet MF 4-6 (3-8) MONOG? F: ? DAYS MF FRUIT FOLIAGE GLEAN BREEDING: Open, riparian, burned, or cutover woodlands, other open country with scattered trees. 2? broods. DISPLAYS: Courting male sings and flutters in front of female, wings half open, tail spread, then perches beside and preens female, and may offer food. NEST: Often in woodpecker-excavated cavity; loose cup of grass, weed stems, pine needles, twigs, occ with hair or feathers. EGGS: Pale blue to bluish-white, occ white, unmarked. 0.8" (21 mm). DIET: Includes earthworms, snails, other invertebrates; esp berries. Young presumably fed primarily insects. Hawking often from low perch catching insects near ground. CONSERVATION: Winters mostly within U.S. Blue List 1972, 1978-81, Special Concern 1982, Local Concern 1986; decline continues in some areas. Felling dead trees and removing dead branches reduces nest holes and increases competition with other cavity-nesting species (esp House Sparrows and European Starlings). Will use nest boxes. Rare cowbird host. NOTES: Often successfully defend nest hole against swallows, House Wrens, and House Sparrows. STANFORD. NOTES: Fairly common resident at the Dish, around Lake Lagunita, the Arboretum and the Golf Course. Also occasionally viewed in the inner quad foraging on berries of lantana bushes. Uncommon elsewhere on campus, occurring primarily in habitats having oaks interspersed with open grassland or fields. Nests in natural cavities, woodpecker holes, and artificial nest boxes. Stanford hosts four bluebird trails (linking nest boxes) at the Dish, Lake Lagunita, the Arboretum, and the Golf Course. Trails monitored weekly during nesting season (March through the end of July). Annual data viewable at arastradero.org. Volunteers (especially long-term residents) interested in monitoring, banding or GIS mapping contact David (Tex) Houston atTex@acterra.org 650-962-9876 ex 347. If interested in helping with the Lake Lagunita trail, in particular, contact Sara Timby (stimby@stanford.edu). ESSAYS: European Starlings; Blue List; Helping to Conserve Birds-Local Level; Great Plains Hybrids; Avian Invaders REFERENCES: Bent, 1949.