Francis Willughby was an English ornithologist and ichthyologist. He was a student, friend and colleague of the naturalist John Ray at Cambridge University, and shared some of his expeditions and interests. Ray saw Willughby's Ornithologia libri tres through the press after Willughby's sudden death.
At Cambridge Francis Willughby was taught by the naturalist John Ray. In 1662 they travelled to the west coast of England to study the breeding seabirds. Between 1663 and 1666 they toured Europe together, travelling through the Netherlands, Germany, Switzerland, Italy and France. They separated at Montpellier and Willughby returned home via Spain.
On returning to England they made plans to publish the results of their studies. Willughby died from pleurisy during the preparation of this work, but Ray published Willughby's Ornithologiae libri tres in 1676, with an English edition two years later. This is considered the beginning of scientific ornithology in Europe, revolutionizing ornithological taxonomy by organizing species according to their physical characteristics.
Willughby and Ray were among the first to dismiss the older inaccuracies of Aristotle. Aristotle had claimed that swallows hibernated but Willughby and Ray (1678:212, quoted in Raven 1942:328) wrote: "To us it seems more probable that they fly away into hot countries, viz. Egypt, Ethiopia etc." Ray also published Willughby's De Historia piscium (1686).