Europeans' first recorded encounters with California grizzly bears are found in diaries kept by several members of the 1769 Portola expedition, the first European land exploration of what is now the state of California. Several place names that include the Spanish word for bear ("oso") trace their origins back to that first overland expedition (e.g. Los Osos). As the settled frontier of New Spain was extended northward, settlers began to populate California and establish large cattle herds as the main industry. The ranchers’ domesticated livestock were easy prey for the grizzly bears roaming freely across the state. By eating their livelihood and scaring them, the grizzlies became enemies of the rancheros. "Vaqueros" hunted the grizzlies, often roping and capturing them to be pitted against other animals in public battles.