How does aspergillosis primarily affect a hawk?

Aspergillosis is a fungal infection caused by the Aspergillus species, and it primarily affects the respiratory system of birds, including hawks. The infection occurs when birds inhale the fungal spores, leading to inflammation and infection in the lungs and air sacs. This can result in severe respiratory distress, which may manifest as coughing, difficulty breathing, or abnormal sounds when the bird breathes.

The susceptibility of hawks to aspergillosis is heightened in conditions where there are high levels of stress, immunosuppression, or poor environmental hygiene. In the wild or in captivity, exposure to moldy food or bedding can also increase the risk of infection. The impact on the respiratory system can be significant and can lead to mortality if not diagnosed and treated promptly.

The other systems listed in the options are not primarily affected by aspergillosis. While it is possible for the fungus to cause secondary infections or effects on the nervous system or digestive system if the respiratory system is compromised, these are not the primary sites of infection.