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 is very large, and hence does not 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.
Wetlands International (2018) estimates the population at c.1,146,000-2,061,000 individuals.
Although Wetlands International consider the population trend to be unknown, the population is suspected to be stable in the absence of evidence for any declines or substantial threats.
The Black Noddy has a worldwide distribution in tropical and subtropical seas, with colonies widespread in the western and central Pacific Ocean and more scattered across the Caribbean, central Atlantic and in the northeast Indian Ocean (del Hoyo et al. 1996).
This species inhabits pantropical and subtropical islands, often with small populations dispersed throughout many inshore and oceanic islands. It feeds on small fish and squid, with prey species and proportion of each depending on locality. It often feeds by hover-dipping and contact-dipping. Kleptoparasitism has been observed, and it will associate with other seabirds over schools of predatory fish. Its breeding season varies depending upon locality, with variable colony sizes and nest sites (del Hoyo et al. 1996).
This species is harvested for food in Micronesia and Tokelau (Szabo 2013), although this is not thought to cause significant declines. House Rats Rattus rattus and cats Felis catus are thought to have been responsible for the extirpation of Black Noddy from Raoul Island (Szabo 2013) and remain a problem in the main Hawai’ian islands (Hawaii’s Comprehensive Wildlife Conservation Strategy 2005) and likely much of the rest of the noddy’s range. Invasive herbivores pose a threat through denudation of vegetation, with goats likely responsible for its extirpation on Malden Island (Gochfeld et al. 2018). The denudation of Phillip Island by goats, before they died out in the early 1900s, and subsequent prevention of regrowth by rabbits, before their eradication in 1988, is likely to have contributed to their historical decline on this island (Priddel et al. 2010). Increased SST has been demonstrated to reduce the provisioning rate at studied colonies in the Great Barrier Reef, and above a particular threshold of temperature reproductive success is nil (Chambers et al. 2011). At present this impact appears restricted to a minority of the breeding population, and colonies have become established at new locations which may be related to adaption to climate impacts.
Text account compilers
Ekstrom, J., Calvert, R., Martin, R., Butchart, S., Stuart, A.
BirdLife International (2020) Species factsheet: Anous minutus. Downloaded from http://www.birdlife.org on 04/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/08/2020.