Pākalakala or Gray-backed Tern

Sterna lunata


State recognized as Indigenous
NatureServe Heritage Rank G3/G4 – Vulnerable/Apparently secure
North American Waterbird Conservation Plan - Moderate Concern
Regional Seabird Conservation Plan - USFWS 2005

Species Information

The pākalakala or gray-backed tern (Family: Laridae) is endemic to the central Pacific and breeds on small and remote islands and atolls, however, its historical and current distribution is poorly known. Adults are mostly slate gray above and white below with a black crown and nape. Forehead has a narrow white patch that is continuous with white eye-brow that extends above and past eye and is completely bordered with black. Flight is direct and graceful and body appears to move up and down with each wing beat. Outside the breeding season, may remain in flight continuously. Often forages with ‘ewa‘ewa or sooty terns (S. fuscata) and ‘ua‘u kani or wedge-tailed shearwaters (Puffinus pacificus). Pākalakala (gray-backed terns) feed mainly by plunge-diving or by dipping the surface while hovering. Diet primarily consists of fish, especially five-horned cowfish, juvenile flyingfish, goatfish, herring, and dolphinfish, but also eats squid, crustaceans, mollusks, and marine and terrestrial insects. Pākalakala (gray-backed terns) nest in shallow depressions in sand or gravel, and like most seabirds lay a single egg per season. In Hawai‘i, nesting season varies from year to year, but most eggs are laid in February and March and most nestlings fledge by late July. Both males and females incubate the egg, and brood and feed the chick. Oldest known bird was 25 years old.

Distribution & Abundance

Pākalakala (gray-backed terns) breed throughout NWHI, and a few pairs
have been recorded breeding on Moku Manu off of the island of O‘ahu. Outside of Hawai‘i,
pākalakala (gray-backed terns) nest on the Marianas, Howland and Baker, Johnston, Wake,
Jarvis, Line Islands, American Samoa, the Marquesas, and Tuamotu. The non-breeding distribution
includes the central Pacific Ocean.

In Hawai‘i, the population is estimated at 44,000 breeding pairs, with largest
populations occurring on Lisianski (20,000 pairs), Nihoa (12,000 pairs), and Laysan (10,000
pairs). Worldwide population unknown but likely on the order of 70,000 breeding pairs.