How have pigeons in eastern North America evolved?

Becuase of my geographicaly different collecting locations,  the transfer of disease in-between populations on equipment used in this research is possible. To limit the chance of this happening, the cardboard boxes used for bird containment will be discarded after the last collection session at a specific site. If any birds are noticeably sick, they will be isolated in the pet carrier and get treatment. The carrier will be washed with vinegar after every use.