Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The combined populations of Anous ceruleus and A. albivittus are estimated to number 27,000-120,000 individuals, but the total for A. albivittus is unknown.
The overall population trend is stable, although some populations have unknown trends (Delany and Scott 2006).
This species takes very small fish (average length 17 mm), squid, crustaceans and pelagic sea striders with proportions varying seasonally and geographically. It feeds on the wing by dipping or pattering. Breeding can be continual in places and occurs in loose colonies on cliffs or rocky areas (del Hoyo et al. 1996).
Globally, the species does not seem to be facing any significant threats, however, the Easter Island population is thought to be threatened, with few individuals observed during recent visits and cats Felis catus predation identified as the principal threat (Marin and Caceres 2010).
Text account compilers
Martin, R., Butchart, S., Stuart, A., Symes, A., Taylor, J., Ekstrom, J., Calvert, R.
BirdLife International (2020) Species factsheet: Anous albivittus. Downloaded from http://www.birdlife.org on 25/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/09/2020.