John James Audubon's five-volume Ornithological biography (1831–1839), published as the textual companion to The birds of America (1827–1838), remains a rich source of information about North America's avifauna. Issued separately from the prints for both practical and economic reasons, this classic but often forgotten work contained individual biographical accounts of each species shown in the illustrations, based upon the naturalist's decades of field observations. The demands associated with the publication and marketing of the prints compelled Audubon to wait until the end of 1830 before he began to write it, just as the first volume of 100 plates was being completed. Assisted throughout the endeavour by Scottish ornithologist William MacGillivray, who edited Audubon's manuscripts and provided scientific descriptions of each species, the naturalist published the first volume in 1831 in both Edinburgh and Philadelphia, the latter to secure the US copyright. A second Philadelphia edition appeared in 1832. Succeeding volumes were published in Edinburgh in 1834, 1835, 1838, and 1839, following the completion of each of the remaining three volumes of plates. An American edition of the second volume was published in 1835, but almost three-quarters of the copies were destroyed in a Boston fire. With sales of the last three volumes lagging, significantly fewer than 750 complete sets were ever sold.