(a) Sierra del Carmen showing six sampling sites at high elevation (above 2300 m, dark grey) and low elevation (1500–2300 m, light grey). Bar graphs above sites show relative basal area of oaks (white) and pines (black). (b) Relative number of acorns (white) to pine seeds (black) identified from feeding observations of jays at high and low elevations (d.f.=1, p=0.01). (c) Sampling locations in the United States (1, Chisos Mountains, Texas, n=10) and Mexico (2, Sierra del Carmen, n=96; 3, Rancho La Escondida, Serranías del Burro, n=20; 4, Rancho Las Cabras, Sierra Santa Rosa, n=5; 5, Rancho La Rosita, Sierra Santa Rosa, n=10; 6, El Taray, Sierra de Arteaga, n=10; 7, Ejido La Encantada, Sierra Peña Nevada, n=3). The Chiricahua Mountains are labelled site 8 in the small inset.