Evening Grosbeak Coccothraustes vespertinus Cooper       Field Guide IDs: NG-454; G-310; PE-272; PW-pl 55; AE-pl 384; AW-pl 426; AM(III)-346 Nest Location Nest Type Eggs & Mating System Dev. & Parental Care Primary & 2ndary Diet.. Foraging Strategy F I: 11-14 DAYS ALTRICIAL DECID .....TREE 20 feet - 100 feet F 3-4 (2-5) MONOG? F: 13-14 DAYS MF FRUIT INSECTS FOLIAGE .....GLEAN BREEDING: Coniferous and mixed coniferous-deciduous forest, second growth, parks. Primarily at higher altitudes in coniferous forest in w. 2? broods. DISPLAYS: Courting male crouches low, puffs out plumage, extends and rapidly quivers wings; male and female may alternately bow. Male does not sing during display but female may occ call; male may occ feed female. NEST: Frail structure usu well out on horizontal limb; of twigs, sticks, roots, lined with fine materials. EGGS: Blue or blue-green, marked with brown, gray, purple, occ black. 1.0" (24 mm). DIET: Insects only in breeding season, for up to 20% of diet; seeds of trees and shrubs, occ of forbs; juniper berries and pinion nuts in w mountains. Fond of maple sap and buds of deciduous trees and shrubs. Nestlings fed well-masticated insect larvae and crushed seeds of fleshy fruits. Often feeds on dirt and gravel for minerals and salts. CONSERVATION: Winters s sporadically to Oaxaca. Frequent highway casualty when seeking road salts. Rare cowbird host. Breeding range expanded e since 1900. NOTES: Male feeds incubating female. Very tame. Highly irruptive. Wings longest relative to body size of all N.A. finches. STANFORD. NOTES: ESSAYS: Irruptions; Feeding Birds; Range Expansion; Wing Shapes and Flight. REFERENCES: Bekoff et al., 1987.