Domestic cats are one of the biggest killers of small birds and wildlife. If you own a cat, keep it indoors and never let it outside without direct supervision. If you own a cat, make sure it is fixed so to better control the domestic cat population. We have way too many cats that do not have a proper home because people let them breed out of control.

Birds also need clean water -- if you live where it freezes in the winter, a heated bird bath will attract so, so many birds. In summer, put a fountain splasher in and you can attract hummingbirds as well. I wash the bath every day (just soap and water).

But the most comprehensive answer to support birds is to get rid of lawns and plant native plants and trees! When I owned a house, I worked to replace much of my lawn with native plants and smaller shrubs that supported birds (cover, places to perch, berries and seeds) and also supported bugs, etc that birds eat.

Within a year or two of planting lots of native plants, we were getting so many different varieties of bugs and birds (and other wildlife - toads, skinks, etc). Added bonus is selecting plants for your soil and light conditions so the plants I selected needed basically no attention once established: no watering in summer, no fertilizer, obviously no pesticides and just scattered straw in fall.