Many raptor species I have visited at the nest are hosts for several parasite species. Feather lice are not common, in my experience, with down phase eyasses but Blowfly larvae is a different story. These larvae (maggots) tend to holdup in the ear apertures during the daylight hours. They normally are not life threatening themselves but should the eyas already be vulnerable because of other stress causing then the parasite may make the difference between death and survival.

As an example this hawklet had approximately 1 dozen larvae per ear and a few days later I removed 5 much larger larvae pictured above.

The larvae are easily removed by administering mineral oil into the ear aperture which cuts off the air supply causing the larvae to come to the surface. A good indicator of their presence is a dark crusty matter around the rim of the aperture. Because dealing with them is such a simple and non-evasive procedure I recommend any eyas be treated for possible removal. A pair of fine tapered tweezers or forceps is the only tool necessary.