Yellow Warbler Dendroica petechia Linnaeus       Field Guide IDs: NG-382; G-278; PE-238; PW-pl 50; AE-pl 357; AW-pl 410; AM(III)-126 Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy F I: 11-12 DAYS ALTRICIAL TREE 1 foot - 14 feet (To 60 feet) F 4-5 (3-6) MONOG F: 9-12 DAYS MF BARK GLEAN HAWKS HOVER & GLEAN BREEDING: Habitat generalist in e: well-watered second-growth woodland, gardens, scrub; in w, riparian thickets. ? broods. DISPLAYS: Courtship: male persistently pursues female for 1-4 days. NEST: Usu compact, neat, strong, of weed stalks, shredded bark, grass, lined with fine materials. EGGS: Off-white, occ pale green, marked with browns, olive, gray, from barely spotted to strongly blotched, usu wreathed. 0.7" (16 mm). DIET: Also few berries. CONSERVATION: Winters s to Bahamas, n Mexico, s to Peru, Bolivia, and Brazilian Amazon. Blue List 1973-82; Special Concern 1986. Populations in w increase where reduction of grazing and cessation of herbiciding willows has led to regrowth of riparian veg. One of the 3 most frequent cowbird hosts; often destroys cowbird egg by burying in bottom of nest where egg cools and dies. NOTES: Occ polygynous. Males forage higher in trees than females, and in trees with less dense foliage than those used by females; presumably this enables male to more efficiently advertise his territorial ownership while foraging, and minimizes conspicuousness of female. Females occ steal nesting material from each other. Quite tame garden bird in e. STANFORD. NOTES: Uncommon migrant in various habitat types throughout campus. Breeds in the Stanford vicinity, but no suitable breeding habitat (riparian vegetation dominated by cottonwoods, willows, and alders) is present on main campus. ESSAYS: Head Scratching; Determining Diets; Cowbirds; Blue List; Polygyny. REFERENCES: Biermann and Sealy, 1982; Busby and Sealy, 1979; DellaSala, 1986; Taylor and Littlefield, 1986.