@Sheril @GeriAQuin Thank you for providing the link to this dubious USFWS report. They admit the flaws in their report:
"Many additional human-caused threats to birds, both direct (causing immediate injury/death) and indirect (causing delayed negative effects to health or productivity) are not on this list because the extent of their impact is either not currently well researched or easily quantified. For instance, habitat loss is thought to pose by far the greatest threat to birds, both directly and indirectly, however, its overall impact on bird populations is very difficult to directly assess."