Warbling Vireo Vireo gilvus Vieillot       Field Guide IDs: NG-310; G-266; PE-226; PW-pl 49; AE-pl 454; AW-pl 514; AM(III)-104 Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy MF I: 12 DAYS ALTRICIAL SHRUB 30 feet - 90 feet (4 feet - 90 feet) MF 4 (3-5) MONOG F: 16 DAYS MF BERRIES HOVER & GLEAN BREEDING: Open deciduous and deciduous-coniferous woodland, riparian forest and thickets. ? broods. DISPLAYS: Female quivers wings, often in response to courtship song of male. Most courtship occurs within 30' of nest. Audubon reported that male struts around female with wings and tall spread. NEST: Usu high in tree, often lower (<30') in w in tree or shrub; very well made, compact, basketlike deep cup, suspended by rim from prongs of forked twig; of bark strips, leaves, veg fibers, grass. EGGS: White, spotted with browns, black. 0.8" (19 mm). DIET: Almost entirely insects, some spiders; few berries. CONSERVATION: Winters from n w Mexico s to El Salvador. Common cowbird host, does not attempt to destroy their eggs. Has declined in urban areas from pesticide spraying of shade trees. NOTES: Forages and sings mostly in treetops. Fearless around nest. Both sexes brood. STANFORD. NOTES: Uncommon migrant throughout campus. A fairly common breeder in riparian and foothill areas nearby, but not known to breed on campus. ESSAYS: Bird Guilds; Brood Parasitism; DDT and Birds; Cowbirds REFERENCES: Howes-Jones, 1985.