Aspergillus fumigatus likes high temperatures and its optimum temperature for growth is about 37C (blood temperature). It is not surprising, therefore, that it is also known as a parasite of humans, other mammals and birds. In humans it has been reported as a causal agent of aspergillosis of the eye. In birds it can cause serious pulmonary infections of turkey poults, penguins, and other birds in captivity.
In nature it is commonly associated with hay that has become wet and undergone heating. Aspergillus fumigatus can grow at temperatures of 50C or higher.