Kōlea primarily feed on terrestrial insects, such as cockroaches, moths, caterpillars, and earwigs, which they locate by sight. During the breeding season, they also consume berries, leaves, and seeds. Kōlea show high site fidelity to wintering grounds and will chase intruders from their territories while foraging. Hawai‘i is thought to support a large proportion of the world’s wintering Kōlea population.

Kōlea winter across the tropical Pacific, in upland and coastal areas from Hawai‘i to Japan. In Hawai‘i, kōlea are more common in the NWHI year-round, but are also commonly seen on all of the MHI between August and May.

The winter range of Kōlea is extremely varied, including crop fields, pastures, coastal salt marshes, mudflats, beaches, mangroves, grassy areas at airports, cemeteries, athletic fields, parks, residential lawns, golf courses, roadsides, and clearings in heavily wooded areas. In Hawai‘i, birds also utilize open stands of ironwood (Casuarina spp.) and small urban lawns and gardens, particularly in areas such as downtown Honolulu. Military bases and airports often provide important wintering grounds. Where suitable habitats (pastures, etc.) occur on mountain slopes, Kōlea range to at least 2,500 meters (8,125 feet) elevation. Extensive land-clearing in Hawai‘i, dating back to the Polynesian colonization, has probably improved wintering conditions by creating open habitat with plentiful insects

Kōlea are currently listed as Least Concern on the IUCN redlist. Their expansive range and large global population, comprising approximately 190,000 to 250,000 individuals, are significant contributors to this listing. The overall population is currently decreasing, but the decline is not substantial enough to warrant moving this species to Near Threatened status. 

There is no current action plan for this species, but it has been recognized in both American and international legislation. The US Migratory Bird Act prohibits hunting or exploitation of any birds breeding throughout Alaska. In Hawaii, the hunting of Kōlea, which was a historical threat, was outlawed in 1941.

Hunting was a significant threat until 1941, when it was prohibited, and populations are thought to have rebounded since then. The effects of pesticide exposure on wintering grounds and along migratory routes are unknown; however, on golf courses in Hawai‘i, Kōlea come into contact with herbicides and pesticides that may be harmful. Aircraft strikes at Līhu‘e (Kaua‘i) and Kahului (Maui) airports occur occasionally in the fall, apparently as naive juvenile birds attempt to establish foraging territories on airport grounds.