Conservationists nurture the American condor on a diet of stillborn dairy calves, but weaning them onto marine meat might help them survive without human help. A team led by Stanford University scientists reconstructed dietary sources of recent and ancient condors by measuring carbon and nitrogen isotope concentrations in feather and bone remains. Condors seem to have mixed sea mammals into their diet after the last ice age, the researchers conclude. They also found signs of a second shift, from surf and turf back to land beasts alone, corresponding to the time when human settlers began hunting seal and whale. Reintroducing marine fare to condors' diets might create self-sustaining populations, the group suggests in the November 15, 2005, Proceedings of the National Academy of Sciences USA.