More than half of the donations from America’s top 10 philanthropists last year came in the form of bequests, The Chronicle of Philanthropy’s Philanthropy 50 survey has determined.

Seven of the 10 donors had pledged the money to colleges, foundations, and other nonprofit organizations after their deaths. In 2007, by comparison, all of the top 10 donors were living. The shift suggests that economic uncertainty may be prompting the wealthiest philanthropists to put off their biggest gifts, The Chronicle said.

Major bequests to academic institutions included $136-million each to Tufts University and Lesley University from Frank C. Doble, who died in 1969 and set up two trusts for those universities. The trusts held a majority stake in his engineering company and were dissolved when it was sold. He was No. 7 on the donor list.

Le Moyne College and Georgetown University were major beneficiaries of a bequest from Robert L. and Catherine H. McDevitt, No. 8 on the list, who left $50-million to Le Moyne and $75-million to Georgetown.

Among the top living donors were David G. and Suzanne D. Booth, who gave $300-million to the University of Chicago. —Kathryn Masterson