[1][2][3][4] Parnell was born in Greenville, North Carolina, where the immediate proximity of his childhood home to the banks of the Tar River fostered an early love of nature.

[5][6] These seeds of childhood curiosity began to take greater root after a move to the city of Jamestown, New York, the birthplace of American naturalist Roger Tory Peterson.

[8][9] After several additional moves, Parnell spent his teenage years in small-town Pennsylvania before attending Case Western Reserve University in Cleveland, Ohio, where he would eventually reside.

[12][13] After having failed to identify a suitable, comprehensive replacement for his mother's booklet, he began to compose the framework of what would eventually become his collected series of field guides.

[21] In addition to the naturalist-specific works of Roger Tory Peterson, Parnell cites Herman Melville, Jack London, and Jorge Luis Borges as literary influences.