GRIT-USE PATTERNS IN NORTH-AMERICAN BIRDS - THE INFLUENCE OF DIET, BODY-SIZE, AND GENDER

We investigated avian grit use by examining the gizzard contents of 14 40 birds collected from 12 states. Grit was present in gizzards of 62 of 90 species and Varied greatly in number and mean particle size. Giz zards of granivorous birds contained more grit particles than those of insectivores, omnivores, and frugivores. Grit particle characteristic s (mean size, shape, and surface texture) did not differ among birds c onsuming different diets. Mean grit size increased linearly with the c ommon logarithm of the bird body mass. Within avian species, grit-use patterns did not differ by gender. Grit use is widespread among birds, and diet strongly influences the amount of grit used by birds.