Peter Custis, born in 1781 in Accomack County, Virginia, was the first trained naturalist appointed to a United States government exploring party. For four months in 1806, before the expedition was turned back by Spanish opposition, he performed a wide-ranging scientific survey of the Red River in what is now Louisiana, Arkansas, and Northeast Texas. Though many have viewed the Red River expedition as both a scientific and diplomatic failure, Custis deserves recognition as the first trained naturalist to work in Texas and the near Southwest.
He entered the University of Pennsylvania in 1804 as a medical student and became a protégé of Benjamin Smith Barton, America's leading academic naturalist. President Thomas Jefferson's selection of Custis for his Red River exploring party came after a consideration of several famous naturalists, including William Bartram, Constantine Samuel Rafinesque, and Alexander Wilson, none of whom was available at the time the position was filled. Custis was appointed by Secretary of War Henry Dearborn in February 1806. He was to receive three dollars a day plus expenses. Although Thomas Freeman was the sole field leader and Capt. Richard Sparks the ranking officer of the party, Custis was one of its two diarists, and the expedition is sometimes referred to as the Freeman and Custis expedition.
Custis's Red River work suffered in three respects. Most important was his inexperience as a naturalist, which made him cautious in declaring new species, though he did declare twenty-one new ones and propose seven new scientific names. Today only a pair of vertebrates can be credited to him. Second was the loss or misplacement of his botanical collections; only two specimens, both of them plants first collected in 1806, survive. Finally, Custis's work was not well published, for it appeared in garbled form in an almost unnoticed government report. A brief article concerning the first leg of the exploration was published in the Philadelphia Medical and Physical Journal in 1806, but most of Custis's discoveries and his manuscript reports were forgotten. His notes, on 267 species of plants and animals inhabiting the Red River valley, are today an invaluable reference for environmental history.
Custis received little acclaim for his work and was not invited to join Jefferson's planned but never accomplished 1807 Arkansas River expedition, perhaps because he was finishing his M.D. degree that year. Later in 1807 he collected plants for Barton. By 1808 he had settled in a position as a doctor in New Bern, North Carolina. He died there on May 1, 1842, leaving a plantation and slaves to his wife and six children, several of whom were named after prominent naturalists.