Wow lucky you -- To have pheasants in your yard!
Full disclosure - I have never had pheasants in my yard, so I have absolutely no experience with them, but I am so envious of your good fortune that I looked it up.
pheasants are omnivores and :
"In fall and winter, Ring-necked Pheasants eat seeds—especially grain from farm fields—as well as grasses, leaves, roots, wild fruits and nuts, and insects. Their spring and summer diet is similar, but with a greater emphasis on animal prey and fresh greenery. They eat insects such as grasshoppers, beetles, caterpillars, crickets, and ants, as well as snails and earthworms. Ring-necked Pheasants forage in grasslands, hayfields, woodland edges, and brushy areas. They sometimes pick waste grain from cow manure in pastures. Pheasants take most of their food from the ground, scratching or digging with their bills. They can retrieve roots or seeds from as deep as three inches below the soil surface. They also sometimes forage in shrubs or trees for fruit, leaves, and buds."
So I guess they could harm your garden especially if they dig up your just-planted seeds..., but all of those caterpillars, grasshoppers, beetles, and snails that they also eat surely must count for something.
There is a picture of the gorgeous creature on that website too, but it is copyrighted, & don't know if it is ok to include.
Here is one from wikipedia: