While reading about what foods are healthy for pigeons, I came across the following paragraph: (Source)
Human interaction and improper feeding of domestic and wild pigeons is believed to be one of the reasons for the birds' decline. While many urban areas claim that pigeon populations are out of control, the truth is that around 59 species are currently threatened by extinction, which is over 20 percent of the pigeon population. Since the 1600s, 10 species of pigeon have become extinct. While habitat loss and over-hunting are partly to blame, bird specialists believe that domestication and improper feeding has weakened the entire species.
There are no sources cited. What does "weakening the entire species" even mean? What evidence is there to support the claim that improper feeding is weakening entire species of pigeons? How would overfeeding by humans lead to extinction? And how would domestication be contributing?