The sudden ouster and subsequent return of University of Virginia President Teresa Sullivan has college leaders on alert that their campus careers are increasingly vulnerable.

A recent survey of more than 1,600 American college and university presidents shows their average tenure is 7 years, compared with an 8 1/2-year average in 2006.

More college presidents are from outside academia -- 1 in 5 in 2011. And nearly one-third of campus leaders in the American Council on Education's presidential survey never were faculty members.

At the same time, ACE surveys show that fewer chief academic officers are interested in becoming president of their institutions.

University presidents at Illinois, Oregon, Texas A&M and Wisconsin are among those who resigned or were forced out in the past year after brief stints.

AP-WF-07-05-12 0642GMT