As Richard and Joan Ostling have written, "Mormons remember." There has been an official church historian since the organization of the LDS Church, and "Mormon youths and their sisters are exhorted to keep journals as part of their religious commitment. Missionaries are reminded by their superiors that the journals represent a part of their sacred duties." The pioneer era is an especially fertile field for faith-promoting history. As Wallace Stegner has written, the "tradition of the pioneer that is strong all through the West is a cult in Utah." Mormons "tell and retell their stories of pioneer privations and persecutions." Mormon young people are often given the opportunity to pull a handcart through a patch of desert; Mormon children are early taught the miracle of the gulls, the story of seagulls that supposedly saved the crops of the earliest Utah pioneers from an invasion of crickets in 1848.