Californians are getting older, and so are their physicians. In isolated towns, fears are rising that as greater numbers of doctors retire, there won't be enough to take their place. The dilemma looms particularly large in Mendocino County, whose 159 doctors, as a group, are among the oldest in California. A 2009 UCSF survey found that half of the county's physicians were older than 56. Efforts to find replacements for aging doctors have produced mixed results at best in rural areas, where many healthcare professionals regard the looming prospect of too many patients and not enough doctors to treat them as nothing short of ominous. Drawn to the higher incomes, broader cultural pursuits and diverse recreational opportunities commonly found in big cities, most new doctors in California today shun small towns to practice in and around the Bay Area, Los Angeles and other urban centers.