Police on Long Island were searching Wednesday for the photographer Peter Beard, known for creating elaborate collages from documentary images of Africa, after he disappeared on Tuesday afternoon from his home in Montauk, N.Y.

Mr. Beard, 82, has dementia, according to the East Hampton police, who described him as “vulnerable” and potentially in need of medical attention. On Wednesday afternoon, dozens of police and firefighters, using dogs, drones and thermal imaging equipment, combed the area around Mr. Beard’s waterfront property, where he maintains his studio and lives with his wife, Nejma Beard, who manages his career.