LC
Black Storm-petrel Hydrobates melania



Justification

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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to 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.

Population justification
The global population is estimated to number 600,000 mature individuals (Partners in Flight 2019).

Trend justification
The species is undergoing a moderate decline (Partners in Flight 2019), which is thought to be caused by predation by invasive species.

Distribution and population

This species breeds on islands off the coast of southern California (U.S.A.), the Baja Peninsula and the Gulf of California (Mexico). During winter it disperses south and can be found off the coasts of Colombia and Ecuador.

Ecology

The Black Storm-petrel can be found foraging inshore and offshore, feeding on planktonic crustaceans (particularly larvae of the spiny lobster) but also small fish and offal. It breeds on islands adjacent to the coast and sometimes in rocky areas, generally nesting in disused auklet (Alcidae) burrows or in rocky crevices. It forms colonies to breed, which begins in May (del Hoyo et al. 1992).

Threats

Invasive predators pose a considerable threat to Black Storm-petrels, with cats Felis catus having been introduced to 16 islands where they would be expected to nest, and House rats Rattus rattus introduced to 9 such islands (Ainley and Everett 2001). Populations of Black Storm-petrel are absent or tiny on the islands with introduced cats, but large on those islands where cats have been eradicated (Ainley and Everett 2001). Black Storm-petrels persist in high numbers on the San Benito Islands despite rat introduction, although this may be due to protection provided by the abundance of Cholla cactus (Ainley and Everett 2001). Black Storm-petrels are planktivores and, as such, sea surface temperature anomalies and ENSO events have an impact on the distribution of available food. It is thought that the Canal de Ballenas acts as a refuge with high prey abundance during ENSO years (Tershy et al. 1991).

Acknowledgements

Text account compilers
Hermes, C.

Contributors
Butchart, S., Calvert, R., Ekstrom, J., Fjagesund, T., Martin, R., Miller, E. & Stuart, A.


Recommended citation
BirdLife International (2022) Species factsheet: Hydrobates melania. Downloaded from http://www.birdlife.org on 19/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/08/2022.