Aspergillus fumigatus

Aspergillus fumigatus is an opportunistic fungal pathogen that birds are more susceptible to infection with upon inhalation of its spores, due to the unique respiratory system of birds.

Where A. fumigatus is found
A. fumigatus is commonly found in damp soil, decaying organic debris, decaying vegetation, old feed grains, moldy or dusty hay or straw, bark, and wood shavings often used for bedding. Damp conditions enhances the growth of A. fumigatus.

Route of transmission
If disturbed by foot traffic, pecking birds, vehicles, or high winds, A. fumigatus releases a large number of spores (called conidia) into the atmosphere which are inhaled by nearby birds. When large amounts of spores are inhaled by birds, it increases the chance that the bird will develop Aspergillosis, since more spores are allowed to germinate, resulting in an inflammatory response.