What are Hippoboscids known to do to hawks?

Hippoboscids, commonly known as louse flies, are ectoparasites that infest birds, including hawks. The correct answer highlights their role in transmitting diseases and causing anemia in these birds. These flies feed on the blood of their hosts, which can lead to significant blood loss, particularly if infestations are heavy. The feeding behavior of Hippoboscids can weaken a hawk’s overall health, making it more susceptible to illness and reducing its ability to hunt and fly effectively. Additionally, they can transmit various pathogens and parasites that further compromise the health of their avian hosts.

Other options describe potential benefits that Hippoboscids do not provide. They do not supply essential nutrients, serve as predators, or assist in feather growth, as their primary interaction with hawks is parasitic rather than beneficial.