He was also an ornithologist, specialising in parrots and budgerigars, to whom he would feed chocolates, although his eldest son was often reduced to eating them; his other pets included a spider to whom, according to Nancy Mitford's The English Aristocracy, he would regularly feed roast beef and Yorkshire pudding.
While known as the Marquess of Tavistock, he wrote "Parrots and Parrot-like Birds".