It usually nests in loosely formed colonies throughout the year, peaking at different times on different islands (Holyoak and Thibault 1984, Carboneras 1992). Burrows are often dug in sand and can be extremely fragile (V. Bretagnolle in litt. 1999), but more often nests are placed under vegetation or in rock-crevices (Holyoak and Thibault 1984, R. Pierce in litt. 2006, 2007). It feeds on small fish, cephalopods and crustaceans (Holyoak and Thibault 1984, Carboneras 1992).

Nesofregetta fuliginosa breeds in the Line and Phoenix Islands (Kiribati), Austral, Society (formerly Tahiti), Gambier and Marquesas Islands (French Polynesia), New Caledonia (to France), Sala y Gomez (Chile) (Vilina and Gazitua 1999), in the Banks Islands (V. Bretagnolle and H. Shirihai  in litt. 2016) and, historically, in Vanuatu, Samoa and Fiji. In the Line Islands, c.1,000 pairs were present on Kiritimati (= Christmas Island) in the 1960s and early 1970s (Garnett 1983) but, in 1993, the population was estimated at several hundred (M. Rauzon in litt. 1999), supported by observations in 1999 and 2007 to 2015 (D. Watling in litt. 1999, R. Pierce in litt. 2015). In the Phoenix Islands, c.1,400 birds were present on Phoenix and McKean Islands, but the total population on the two islands is now thought to be 100+ pairs and c.10 individuals, respectively (Garnett 1983, Pierce 2013). In the Austral Islands, tens of pairs occurred on Rapa and the surrounding islets (Holyoak and Thibault 1984). However, following Cyclone Oli in February 2010, 36 dead birds were found in the port of Tubuai, (possibly through the combined effects of light-attraction and strong winds), which may have had a significant impact on the small local population around Rapa and the long-term survival of the species in French Polynesia. In the Gambier Islands, 100-200 pairs occurred on Motu Teiku and 100-300 pairs on Manui in 1996, but it may have become extinct on two further islands (Thibault and Bretagnolle 1999). In the Marquesas, one pair was found on Ua Pou in 1989 (V. Bretagnolle in litt. 1999). Three to four pairs bred in New Calendonia in 1996-1997 (V. Bretagnolle in litt. 1999), although repeated visits in 2007 failed to produce any records, pointing to local extinction (J. Baudat-Franceschi in litt. 2007). Since then, the species was sighted twice off the northern tip of the island and may possibly breed on atolls (C. Collins in litt. 2011). No evidence was found of this species during a survey of the historical nesting site of Mt Washington (Nabukulevu) on Kadavu (Fiji) in August 2004. There has been only one unconfirmed sighting in Fijian waters in the last three decades, and it is thought to be very unlikely that it still breeds in Fiji (D. Watling in litt. 2005).