Justification of Red List Category
This species has an extremely 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.
Brooke (2004) estimated the global population to number around 150,000 individuals. The European population is estimated at 6,600-6,900 pairs, which equates to 13,100-13,700 mature individuals (BirdLife International 2015).
The population is suspected to be in decline owing to predation by invasive species and unsustainable levels of exploitation. The European population trend is unknown (BirdLife International 2015).
This species breeds in the eastern Atlantic from the Berlengas Islands and the Azores (Portugal), down to Ascension Island and Saint Helena (St Helena to U.K.), and in the Pacific off eastern Japan, on Kauai, Hawaii (U.S.A.), and on the Gálapagos Islands (Ecuador) (del Hoyo et al. 1992).
This marine species is highly pelagic, occurring in warm waters and rarely approaching land except near colonies. It feeds mostly on planktonic crustaceans, fish and squid but will also feed on human refuse. It mainly feeds in the day on the wing by pattering, dipping and also by surface-seizing. Its breeding season varies locally in colonies on undisturbed islets, in flat areas near the sea or inland on cliffs (del Hoyo et al. 1992)
The Band-rumped Storm-petrel is threatened by a number of invasive species, and throughout its range, the species is largely restricted to breeding locations that do not possess invasive mammals. Carcasses of near-fledging chicks have been recovered from burrow entrances on Kaua'i with cat scats also recorded and cats are considered the introduced species responsible for the majority of predation events to date (Slotterback 2002, Raine et al. 2017). Cat predation is also likely to have restricted Band-rumped Storm-petrels to remote and largely inaccessible breeding locations in Macaronesian islands (Monteiro et al. 1999). It is suspected that House Rats Rattus rattus may have contributed to considerable declines and potentially extirpations (Slotterback 2002, Raine et al. 2017). Polynesian Rats Rattus exulans are considered to be restricting the distribution of the species to steep slopes with little vegetation on Lehua Islet (Raine et al. 2017), and this species may be that observed entering burrows on Kaua'i (Galase et al. 2016). Small Indian Mongoose Herpestes auropunctatus are significant predators of the slightly larger Hawaiian Petrel Pterodroma sandwichensis, but have only recently become established on Kaua'i (Duffy and Capece 2014). The severity of impacts from this predator may increase, should the population be allowed to increase and spread. On Kaua'i, the introduced Common Barn Owl Tyto alba is a major predator of adults (Raine et al. 2017). Pigs are considered a significant threat to the species due to their observed impacts on other seabird species (Slotterback 2002); however, there does not appear to be any direct evidence of predation or habitat destruction caused by pigs impacting this species (Slotterback 2002, Raine et al. 2017).
Band-rumped Storm-petrels have been found grounded due to light pollution in the Canary Islands (Rodríguez and Rodríguez 2009, Carboneras et al. 2018) and Hawaii (Slotterback 2002, Raine et al. 2017). Mortality due to striking structures while disorientated has occurred (Slotterback 2002). However, the species appears less prone to 'fallout' than expected, and impacts are therefore likely to be of a lower severity (Rodríguez and Rodríguez 2009, Raine et al. 2017). The threat from introduced predators appears far more severe than that from light pollution at present.The Band-rumped Storm-petrel is thought to have been hunted on a large scale in the early 16th and 17th century, with accounts from the Azores of a small black and white seabird that was killed nightly by the thousands for food and oil (Bolton et al. 2008). However, this threat is highly unlikely to return on anything close to this scale.
Conservation Actions Underway
It is listed in Appendix II of the Bern Convention and on Annex I of the EU Birds Directive. It occurs in 21 existing marine Important Bird Areas in Europe and in the EU it is listed in 17 Special Protection Areas.
Conservation Actions Proposed
The following information refers to the species's European range only: Continued management of invasive predators at breeding colonies. Management of light pollution and shipping traffic to reduce collisions at night.
Text account compilers
Stuart, A., Westrip, J., Ashpole, J, Ekstrom, J., Fjagesund, T., Butchart, S., Hermes, C., Calvert, R., Martin, R., Miller, E.
BirdLife International (2019) Species factsheet: Hydrobates castro. Downloaded from http://www.birdlife.org on 18/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/11/2019.