Why bird populations are declining? [CC] 

Thank you for making this informative video. The birds that my friend and I rescue are mostly Wood Warblers, but also Hummingbirds to Hawks.. A friend & I rescue songbirds when they migrate thru the city, birds hit the glass skyscrapers or fall to the cement, most do not survive. A youtube shows us in Newark NJ, named ( Volunteers give migrating birds injured in N.J’s biggest city a second chance )The Raptor Trust TRT video named ( Window Strikes in the Business District ) of us picking up injured Warblers. TRT gives 100% effort the injured we being to them . I know people like to say "cats" as then it is not human, and easier to see cat causalities -- but I see thousand more birds perished by the glass and do see predators such as Gulls, rodents, and feral cats dragging them away out of sight to eat, Gulls will swallow some withing seconds then fly off with an injured or perished in their beaks. Glad you did not mention lights as even though I hear that is cause all the time, I am not seeing that in Newark the birds smash into the glass with or without lights on, though maybe in other cities it is a issue.