I had that problem using the wrong loads (heavy & larger shot) in my shotgun years back. I switched to 7 1/2 and 8 light field loads and that took care of it. Also are the birds a different distance from you than the targets you shoot at? If so try a different choke and load. What gun and ammo are you using?
S&W 5906 9mm, FN commercial Mauser .270 win, Winchester 94 .30-30, Ruger Redhawk .44 mag, Ruger 10/22 .22lr, Ruger P-95 9mm, Savage 110 .30-06, Norinco SKS 7.62x39mm
I support our constitutional right to arm bears.