The organization put together the graphic to illustrate that lead ingestion plays a very minor role in the death for birds, despite criticism. Here is more about the graphic from The Post:
What’s striking about the pie chart is how big a slice of it consists of predation by free-roaming cats. A large new peer-reviewed study published in 2013 estimates the number of North American birds killed by cats at well over one billion per year. Bells on collars don’t help. Neutering feral cats doesn’t work. Keeping cats indoors helps.