Too many crows eating eggs and chicks.
The crow population here in the South San Francisco Bay Area has just exploded the past 30 years. It was rare to see a suburban crow back then. Now the damned things are everywhere. Back then we had huge Mourning Dove populations and their wonderful plaintive cooing. It was always nice seeing the mated pairs together. Now we rarely see a Mourning Dove anywhere around here.
A lot of birds prey on other birds. In the areas where I’ve lived, we’ve lost far more baby birds to birds - crows, particularly - than ever to cats.