LC
Imperial Shag Leucocarbo atriceps



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). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, 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.

Population justification
The population size has not been quantified owing to a recent taxonomic split.

Trend justification
The overall population trend is uncertain, as some populations are decreasing, while others are fluctuating, stable, or have unknown trends (Delany and Scott 2006).

Distribution and population

Leucocarbo atriceps is found on the southern tip of South America, from central Chile round to central Argentina, and on the Falkland Islands (Islas Malvinas). Leucocarbo atriceps bransfieldensis breeds on the Antarctic Peninsula and the South Shetland Islands. Leucocarbo atriceps georgianus is found on the islands of South Georgia (Georgia del Sur), the South Orkney Islands, South Sandwich Islands (Islas Sandwich del Sur) and Shag Rocks (Scotia Sea). In the Indian Ocean, Leucocarbo atriceps melanogenis occupies the Crozet Islands (French Southern Territories), Phalacrocorax atriceps nivalis is found on Heard Island (to Australia) and Leucocarbo atriceps purpurascens is restricted to Macquarie Island (to Australia) (del Hoyo et al. 1992).

Ecology

This marine species forages in subantartic and Antarctic waters along the coast and around islands. It feeds in inshore waters. Breeding begins in either October or November, forming colonies up to hundreds of thousands of birds which are very dense (del Hoyo et al. 1992).

Threats

The species is not globally threatened, but has variable conservation status on the sub-species level. Seven races are currently recognised and L. a. nivalis is particularly vulnerable due to its extremely limited range and small population size (Orta et al. 2018). On a species level, over-fishing in coastal waters may cause slow but significant declines, while for L. a. nivalis, fishery could pose a serious threat, with the potential to substantially decimate the population, as shown in the past (Green et al. 1998). Predation of eggs and chicks by Kelp Gulls Larus dominicanus and Black Vultures Coragyps atratus has led to complete breeding failures in some colonies in Patagonia in recent years. This threat is currently only affecting a minority of the total population, but is having a serious impact on local scales (Frixione 2010). Disturbance to Antarctic colonies from tourist boats has caused reduced breeding success and a low level of colony abandonment in several colonies. While precautions are now being taken to limit this disturbance, this threat may continue to affect the species in the future (Bó and Copello 2000).

Acknowledgements

Text account compilers
Martin, R., Fjagesund, T., Calvert, R., Shutes, S., Symes, A., Taylor, J., Bennett, S.


Recommended citation
BirdLife International (2021) Species factsheet: Leucocarbo atriceps. Downloaded from http://www.birdlife.org on 07/12/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 07/12/2021.