It breeds on inshore (and occasionally offshore) islands and rocky coastal cliffs. Nests are placed in suitable fissures, burrows, caves and cavities, sometimes the old nest of a Humboldt Penguin Spheniscus humboldti. It feeds, often in large flocks, on schooling anchoveta Engraulis ringens, mote sculpins Normanychtic crokeri and silversides Odothestes regia regia found in the cold water of the Humboldt Current. Additionally, this species scavenges offal and scraps from sea-lions and fishing boats. One or two eggs are incubated for about four weeks, and the chicks leave the nest after seven weeks. Birds feed by plunge diving for fish.

Larosterna inca is found along the Pacific coast from northern Peru south to central Chile. Mass dispersal and breeding failures have resulted periodically from El Niño Southern Oscillation (ENSO) events, and both fish-stocks and the populations of seabirds that depend upon them are adapted to these fluctuations. Population declines are usually promptly reversed, suggesting that food shortages trigger rapid dispersal not high mortality in adults and high reproduction rates (up to two successful broods in a year). Although fishing for anchoveta has been banned in Peru, and the guano industry adequately regulated, there are concerns that this species might be badly affected by the El Niño Southern Oscillation event of 1998 (G. Engblom in litt. 2003). Prior to the guano industry (c.1850) there were millions of Inca Terns in Peru (according to accounts from Coker 1919, Hutchison 1950). Current numbers are much lower than two centuries ago, but they are common and breed in some localities. The total population has been estimated at more than 150,000 individuals (Zavalaga et al. unpublished data).

Conservation Actions Underway
Some breeding sites lie within managed guano reserves or protected areas.

Conservation Actions Proposed
Identify those breeding sites where introduced predators are a problem and control/remove them from these sites. Determine effects of interactions with fisheries. Monitor population levels at key sites. Establish key locations as Marine Protected Areas.