His Fiery Angel by Cynthia Wright

Proudly going her own way
Camille St. Briac cares nothing for her own natural beauty, nor is she interested in the London ton. Instead, she pours her energies into saving Cornwall birds called kittiwakes from those who would kill them to provide feathers for fashionable women's hats.
Escaping from his past
Rakish ornithologist Benedict Hawke travels the world in search of new species of birds... and the farther that takes him from England and his unforgivable father, the better.
But Pa's sudden illness forces Benedict to abandon a dream expedition and return to Cornwall. When feather hunters invade the cliffs near his cottage, Benedict clashes with Camille, a fiery crusader for the beleaguered kittiwakes. Although she believes he is one of the villains, neither can deny their potent, mutual attraction.
Can these two unconventional enemies open their hearts to love and join forces to save the innocent kittiwakes from decimation?