R.E. Johnson 1968 Sparrow Hawk No. 29 Tilden Regional Park, Contra Costa Co., Calif. Overcast, cool, wind from west. 3:30 PM. A Sp. Hk circled, dove, harassed a Red-tailed Hawk which was hovering west of the main n-s ridge top over a grass & weed field. The RT drifted south and finally The Sp. Hk turned + disappeared to the north. Perhaps they compete for aerial hovering space while foraging. They don't compete for food.