Typhon x Echidna?

It never fails to impress how proficient falconers are at: a. shoe-horning one species' sperm into another's oviduct and thus 'improving' species for which evolution has, over millions of years, honed into nigh-perfectly optimised killing machines; and b. losing their birds.

This monster was singularly unimpressed with the whistling and shouting of its green-wellied, flat-capped owner and, despite a downpour, seemed to favour taking up residence within a nuclear power station instead of a ride home in a wooden box in the back of a pick-up, strange huh?!

Luckily, the local Peregrines were absent or I daresay battle royal would have ensued, given this thing was sat pellet-coughing distance from their favourite vantage point.

Care to have a guess at the identity of the beast? Feel free to leave a comment. Just for once with a large falcon hybrid, I know the answer, or at least, I know what the owner thinks the bird is.