Marinus Adrianus Koekkoek, known as The Younger (29 January 1873, Amsterdam - 30 May 1944, Amsterdam) was a Dutchanimal painter, who specialized in birds. He is referred to as "the younger" to distinguish him from his great-uncle, the landscape painter, Marinus Adrianus Koekkoek, after whom he was named.
His career began and ended in Amsterdam. In between, he spent twenty years at the Rijksmuseum van Oudheden, in Leiden, illustrating academic works.[1] He is best-known for his watercolor illustrations; notably Ornithologia Neerlandica: de vogels van Nederland, by Eduard Daniël van Oort, which was published in five parts from 1922 to 1935. He also created color plates for two series of schoolbooks on nature: In Ons Land, and Buiten Ons Land. His last works were a set of postcards for Natura Artis Magistra, a zoo in Amsterdam.