Good question. This is from one of dozens of articles on the subject ...
The Hidden Dangers of Goose DroppingsWhile its definitely disgusting, there’s also a hidden danger tied to goose dropping: dangerous diseases and bacteria like E Coli, Salmonella, Histoplasmosis, Campylobacter, Coccidia, and Giardia.
High concentrations of birds can render beaches and parks completely unusable.
You don't want to throw out a blanket for a picnic in a park infested with Canada Geese or let the kids play on the grass.
Yuk. Doesn’t vagrant drug user poor pose dangers too?