I agree there is a possibility of disease with the pigeon and yes they are dirty birds but it is an option. Any animal you run into in shtf will have most likely been exposed to less than sanitary environmental conditions. Even now a lot of animals have been exposed to chemicals. If you saw what they feed commercial chickens these days you would quit eating chicken. There is also the option of capturing and keeping some animals for a time to control their diet and improve their cleanliness. We do it with wild hogs all the time.
Thanks for the reference matterial. A lot of people think of surviving within the constraints of the law. These books should go a long way in helping their mind set.