As is often the case this poor bird was suffering from more than one problem. His death would have been the result of a combination of conditions.
In this instance, alimentary canal blockage with grass in the crop and gizzard, red mite and lice. I would suspect that the red mite caused anaemia and debilitation which resulted in weakness and excessive consumption of grass which further compounded the weakness. Whilst the lice are unlikely to have caused death. They would most likely have caused irritation and sleep loss which would further have contributed to this birds demise. The picture below shows the lesions seen on post mortem.
Avoidance of this problem relies on careful observation, management and external parasite control.
