John Weaver Fitzpatrick (born September 17, 1951, in Saint Paul, Minnesota^[2]) is an American ornithologist primarily known for his research work on the South American avifauna and for the conservation of the Florida scrub jay. He is currently the Louis Agassiz Fuertes Director of the Cornell Lab of Ornithology in Ithaca, New York.

In 1974, Fitzpatrick graduated magna cum laude from Harvard University with a B.A. in biology. His early inspiration to work on Bird conservation came from a talk by John Terborgh and his travels in the summer of 1974 Manú National Park in south-eastern Peru.^[3] His summer in Peru made him change his plans from pursuing graduate study in University of California, Berkeley. In 1978, he earned a Ph.D. in biology from Princeton University for his study of the foraging behaviour of tyrant flycatchers in Manu.^[4]

After his PhD, he moved to the Field Museum of Natural History in Chicago as its curator.^[5] In 1988, he left for Florida to take over as the executive director and senior research biologist at the Archbold Biological Station, a private ecological research foundation in central Florida.^[5] Much of his early research focused upon neotropical avifauna. He travelled many times to remote areas of South America, in particular to the western Amazonian basin and to the Andean foothills. In 1996, he published Neotropical Birds: Ecology and Conservation, a comprehensive synthesis of ecological information of the region covering 4037 species of birds from Mexico south to Tierra del Fuego.^[6] Along with other biologists, Fitzpatrick has described several species and sub-species new to science such as bar-winged wood wren,^[7] cinnamon screech owl,^[8] royal sunangel,^[9] Manu antbird,^[10] the cinnamon-breasted tody-tyrant,^[11] and the cinnamon-faced tyrannulet.^[12]

In 1995, Fitzpatrick became the Louis Agassiz Fuertes Director of the Cornell Lab of Ornithology in Ithaca, New York. He is also a professor in ecology and evolutionary biology at Cornell University. He continues to teach and mentor graduate and undergraduate students.^[15]

In 2005, Fitzpatrick won the Eisenmann Medal from the Linnaean Society of New York.^[15] In 2011, he was honored with the AOU's Marion A. Jenkinson Service Award, given in memory of Marion Anne Jenkinson (1937–1994), former AOU treasurer. For his achievements in the study of Peruvian birds and his guidance to a new generation of ornithologists, the newly described Sira barbet of Peru was named in his honor in 2012.^[19] In 2016, in a rare instance, the American Ornithologists' Union awarded him a second time (after the Brewster Medal) with the Ralph W. Schreiber Conservation Award.^[15]