Ferruginous a. : Partaking of iron; containing particles of iron.

Ferruginous a. : Resembling iron rust in appearance or color; brownish red, or yellowish red.

Example:
What's the difference between Ferruginous Sandstone, Gauconitic Sandstone, and Flagtone Sandstone?

Taxonomy
Ferruginous Hawk, nest, birds, species, hawks, trees, prey, hunting, wings, ground, flight, population, ground nests, birds of prey, territories, food supply, grasslands, predation.

Defination from the web:
... The preferred habitat for Ferruginous Hawks are the arid and semiarid grassland regions of North America. ... Piracy – the Ferruginous Hawk has been observed gathering around a hunter shooting prairie dogs, ...