White-throated Sparrow Zonotrichia albicollis Gmelin    Field Guide IDs: NG-416; G-340; PE-278; PW-pl 58; AE-pl 539; AW-pl 587; AM(III)-266  Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy F I: 11-14 DAYS ALTRICIAL SHRUB (To 3 feet) F 4-6 (3-6) MONOG? F: 8-9 (7-12) DAYS MF SEEDS FRUIT FOLIAGE .......GLEAN HAWKS.. BREEDING: Conif and mixed conif-decid forest, edge and clearings, thickets, open woodland. 1, occ 2 broods. DISPLAYS: Courtship: female flutters wings and trills. NEST: Usu at edge of clearing, well concealed; of coarse grass, wood chips, twigs, pine needles, rootlets, lined with fine materials. Female probably selects site. EGGS: Greenish-, bluish-, or creamy-white, marked with reddish-browns. 0.8" (21 mm). DIET: Includes few spiders, millipedes, snails; forb, grass and tree seeds. CONSERVATION: Winters s to n e Mexico. Uncommon cowbird host. NOTES: White-striped (WS) and tan-striped (TS) adults tend to mate with opposite-colored morphs; experiments show that male WS are more aggressive than male TS toward singing birds and that female WS sing, thus WS males likely drive off WS females and mate with TS females, which do not sing. Males tend to return to same breeding territory each year. Often sing at night. Foraging behavior largely determined by proximity to cover. Immature and first-year females tend to winter farther s than adults; adult males tend to winter in n. Often associate with other sparrows in winter. Birds in winter flocks form stable dominance hierarchies. STANFORD. NOTES: ESSAYS: Vocal Functions; Dominance Hierarchies; Migration; Site Tenacity REFERENCES: Atkinson and Ralph, 1980; Knapton et al., 1984; Schneider, 1984.